G) Public Health and Infectious Diseases

G.4 Classification by route of infection

Details

Faeces-Food-Water Cluster

Agents in this cluster are found in beverages, food, drinking water and on objects. Numerous outbreaks of gastrointestinal illness have been described, primarily from passenger ships. The main agents documented in outbreaks include Norovirus, E. coli spp, Salmonella typhi, Salmonella spp, Shigella spp, Vibrio spp, Staphylococcus aureus, Clostridium perfringens, Cylsospora spp, Giardia lamblia, Cryptosporidium sp, Trichinella spirali, Entamoeba histolytica, Enterobacter (1,2,3,4)

Dahl analysed gastrointestinal illness logs from 17 cruises in 2004. On average 590 passengers and 611 crew were present per day. During a 250 day period the percentage of GI cases per 7 days varied between 0.10% and 0.43% among passengers and between 0 and 0.29% among crew except for one cruise when percentage per 7 days reached 2.16% among passengers and 0.61% among crew (5).

Occurrence of gastrointestinal infections onboard passenger ships in the 1970´s to 1980´s led to a governmental inspection program in the United States, which is ongoing. The Centers for Disease Control and Prevention´s Vessel Sanitation Program web site lists 15 only outbreaks in 2008 but over 100 outbreaks of gastroenteritis from 1994 (6).

For prevention and control of food and waterborne infections on board ships detailed published recommendations include those of the World Health Organization, the Centers of Disease Control Vessel Sanitation Program (www.cdc.gov/nceh/vsp) (7) and the EU project ShipSan (www.ShipSAN.eu) (8,9).

Guidance documents from the World Health Organization on ship sanitation in general and food and water hygiene in particular are freely available at  http://www.who.int/ihr.

The most relevant documents found on this website concerning food and water hygiene are

  • Handbook for inspection of ships and issuance of ship sanitation certificates
  • Guide to ship sanitation (third edition)
  • Ship sanitation certificates

(1) World Health Organization. Guide to Ship Sanitation 3rd edition 2011 http://www.who.int/water_sanitation_health/publications/2011/ship_sanitation_guide/en/; last access14.2.2022

(2) Jenkins KA, Vaughan GH Jr, Rodriguez LO, Freeland A. Acute Gastroenteritis on Cruise Ships - Maritime Illness Database and Reporting System, United States, 2006-2019. MMWR Surveill Summ. 2021 Sep 24;70(6):1-19. doi: 10.15585/mmwr.ss7006a1. PMID: 34555008; PMCID: PMC8480991.

[3] Rooney RM, Cramer EH, Mantha S, Nichols G, Bartram JK, Farber JM, Benembarek PK. A review of outbreaks of foodborne disease associated with passenger ships: evidence for risk management. Public Health Rep 2004;119:427-434.

[4] Koo D, Maloney K, Tauxe R 1996. Epidemiology of diarrheal disease outbreaks on cruise ships, 1986 through 1993. J Am Med Ass 1996;275:545-547.

[5] Dahl E. Dealing with gastrointestinal illness on a cruise ship – Part 1: Description of sanitation measures, Part 2: An isolation study. Intern Marit Health 2004;55(1-4):19-29.

[6] Vessel Sanitation Program. Surveillance and outbreak information. www.cdc.gov/nceh/vsp. Last access 14.2.2022

[7] The VSP 2018 Operations Manual and updates are available at www.cdc.gov/nceh/vsp, last access 14.2.2022

(8) Mouchtouri VA, Verykouki E, Zamfir D, Hadjipetris C, Lewis HC, Hadjichristodoulou C; The Eu Shipsan Act Partnership. Gastroenteritis outbreaks on cruise ships: contributing factors and thresholds for early outbreak detection. Euro Surveill. 2017 Nov;22(45):16-00576. doi: 10.2807/1560-7917.ES.2017.22.45.16-00576. PMID: 29162205; PMCID: PMC5718393.

[9] ShipSan and ShipSanAct Joint Action  https://www.shipsan.eu, Last access 14.2.2022

Norovirus

Norovirus circulates worldwide. The infection causes vomiting, fever and diarrhoea. Spread is via hand contact, inhalation of aerosols from vomit or diarrhoea and food. Infectivity is high and the infective dose is low. Index infections are often food or waterborne, secondary spread is often person-to-person. Most reports are from passenger ships, where outbreaks caused by Norovirus are showing an increased activity despite detailed infection control plans by most cruise companies.

Norovirus is reported to be the predominant cause of diarrhea on cruise ships in many outbreak reports. Most programs focus  on passenger safety, data on sickness in crew are often lacking (1,2,3,4).

On a US Navy aircraft carrier an outbreak of gastroenteritis occurred in 1997 during coastal exercises in Japan. A cross-sectional study showed an attack rate of 44% from the ship´s population of 4200 persons caused by Norovirus (5).

In one cruise ship from Florida to the Caribbean in 2002, Norovirus outbreaks occurred on six consecutive 7-day cruises despite aggressive sanitization after the second cruise. On cruise 1, 4% (84/2318) of passengers had gastroenteritis. On cruise 3, 8% of passengers (192/2456) and 2% (23/999) of crew had gastroenteritis (6).

In 2006 an increase of outbreaks on cruise ship sailing in Europe between January and August 2006 was recognized. The authors of the epidemiological study showed that the increase was possible due to an increased Norovirus activity in the community which coincided with the emergence of a new strain. 43 outbreaks were reported from 13 vessels. The highest attack rate was 48% for passengers and 19% for crew members. Two ferries showed higher attack rates in crew (13%) than in passengers (10%) (7).

In summer 2006 a Norovirus outbreak on a river cruise-ship was investigated. A retrospective cohort study among passengers and cruises of three successive voyages was performed. Attack rates for crew and passengers differed with a significant lower attack rates for crew (7%) as compared to passengers (47%) (8)

2002 an ongoing outbreak 6 consecutive cruises with Noroviruses (NoV) occured despite a 1-week sanitization (9).

(1) World Health Organization. Guide to Ship Sanitation 3rd edition 2011 http://www.who.int/water_sanitation_health/publications/2011/ship_sanitation_guide/en/; last access 2011

(2) Rooney RM, Cramer EH, Mantha S, Nichols G, Bartram JK, Farber JM, Benembarek PK. A review of outbreaks of foodborne disease associated with passenger ships: evidence for risk management. Public Health Rep 2004;119:427-434.

(3) Koo D, Maloney K, Tauxe R 1996. Epidemiology of diarrheal disease outbreaks on cruise ships, 1986 through 1993. J Am Med Ass 1996;275:545-547.

(4) Dahl E. Dealing with gastrointestinal illness on a cruise ship – Part 1: Description of sanitation measures, Part 2: An isolation study. Intern Marit Health 2004;55(1-4):19-29.

(5) Thornton S, Davies D, Chapman F, Farkas T, Wilton N, Doggett D, Jiang X. Detection of Norwalk-like virus infection aboard two U.S. Navy ships. Mil Med 2002;167:826-830.

(6) Corwin AL, Soderquist R, Edwards M, White A, Beecham J, Mills P, Larasati RP, Subekti D, Ansari T, Burans J, Oyofo B. Shipboard impact of  a propable Norwalk virus outbreak from coastal Japan. Am J Trop Med Hyg 1999;61:898-903.

(7)  Verhoef L, Depoortere E, Boxman I, Duizer E, van Duynhoven Y, Harris J, Johnsen C, Kroneman A, Le Guyader S, Lim W, Maunula L, Meldal H, Ratcliff R, Reuter G, Schreier E, Siebenga J, Vainio K, Varela C, Vennema H, Koopmans M. Emergence of new norovirus variants on spring cruise ships and prediction of winter epidemics. Emerg Infect Dis 2008;14:238-243.

(8) Verhoef L, Boxman IL, Duizer E, Rutjes SA, Vennema H, Friesema IHM, deRoda Husman AM, Koopmanns M. Multiple exposure during a Norovirus outbreak on a river-cruise sailing through Europe 2006. Eurosurveillance 2008;1 3(2)

(9) Isakbaeva ET, Widdowson MA, Beard RS, Bulens SN, Mullins J, Monroe SS, Bresee J, Sassano P, Cramer EH, Glass RI. Norovirus transmission on cruise ship. Emerg Infect Dis. 2005 Jan;11(1):154-8. doi: 10.3201/eid1101.040434. PMID: 15705344; PMCID: PMC3294347.

Hepatitis A

Hepatitis A virus is spread by oral-faecal contact or ingestion of contaminated food. The infectious agent is found in faeces, reaches peak levels a week or two before the onset of symptoms and diminishes rapidly after jaundice or symptoms disappear.

Common sources of outbreaks have been related to contaminated water, food contaminated by infected food handlers, including food not cooked or handled after cooking, raw or undercooked molluscs harvested from contaminated waters and contaminated products such as lettuce and strawberries. Lifelong immunity occurs from vaccination or infection.

Risks of hepatitis A virus infection vary with age, country of origin and destination. Seroprevalence rates are highly correlated with socioeconomic status and access to clean water and sanitation. Adult Hepatitis A is a feature of travelers going from low-risk areas to high-risk areas. Inhabitants of high-risk areas are usually infected during childhood and acquire life-long immunity. Ships move between high and low prevalence areas accommodating seafarers with or without immunity in a semiclosed space. Most highly industrial countries are low prevalence regions, while infection rates are declining in the younger population in most Latin-American, Asian and Middle Eastern. Surveys from Africa indicate that infection rates remain high with no significant decline in rates (1).

A prevalence study among seafarers of US Navy vessels in 1989 showed that 10.1% (210 of 2072 male persons) had antibodies against hepatitis A. Immunity was independently associated with age, non-white racial/ethnic group, birth outside of the United States and prior Caribbean deployment (2).

A historical follow-up study based on record linkage of the research database on 24132 seamen who have been employed in Danish ships between 1986 and 1993 and the National Registry for Notifiable Infectious Diseases showed that the standardized incidence ratio for hepatitis A infection was 1.77 (0.91-3.10) as compared to the general population. The majority of the 15 cases reported an occupational exposure such as overseas travel or repair work of the ship’s sanitary installation (3).

One case report on hepatitis A infection from a cargo ship was published in 2008. The vessel carried a seafarer from the Philippines who was infected during a vacation in his country. Immunity could not be confirmed in fellow crew members by medical history or from documentation in their vaccination cards. As a consequence, post-exposure vaccination of the entire crew was performed by the Port Health Authority in Hamburg (4).

Mouchtouri et al. reported several cases of Hepatitis A infections on river boat cruises in Egypt and points to the importance of pre-tarvel vaccination for crew and passengers (5).

Given the high risk of acquiring the infection during sea travel, including common source infection (food, water) and person-to- person spread, pre-departure Hepatitis A vaccination of all seafarers from low incidence countries is necessary to avoid work-related disease and outbreaks on board. As an alternative to routine immunization, immunological screening can be performed. Cost-effectiveness of this measure must be assessed on the grounds of the country of origin of recruited sailors. Immunization of persons who have acquired natural immunity is not harmful, so routine vaccination of all crew without serological screening may be a cost-effective strategy for companies. Certainly the ship´s cook and engineers with responsibility for the on board sewage system must have highest priority for immunization.

Proper water and food sanitation on board and personal hygiene with special emphasis on hand washing are of prime importance. Maintaining a proper water treatment and distribution system on the ship is a key measure for prevention.

In case of an individual case of hepatitis A occurs on board, the infected person must be isolated in a cabin, with enteric precautions (do not share toilet, dishes, left-over food etc.) observed during the first 2 weeks of illness, but no more than 1 week after the onset of jaundice. Post-exposure prophylaxis with Hepatitis A vaccine, preferably simultaneously with IgG must be given to close contacts within 2 weeks of last exposure at separate injection sites. In the context of a ship, close contacts are all crew members working and living in the same area, thus all crew from a cargo ship. On a cruise ship this must be assessed in detail: Contacts may be persons sharing a cabin or wash rooms or working in the same areas Others to be considered are food handlers, those who work in a day-care center, with the water treatment or sewage and waste systems, or in spas or medical facilities.

Given the safety, good tolerability, efficacy and long lasting protection (20-30 years) of the vaccine, pre- and post exposure hepatitis A vaccination in global seafaring is certainly an underused preventative measure.

[1] Jacobsen KH, Koopman JS. Declining hepatitis A seroprevalence: a global review and analysis. Epidemio. Infect 2004,132:1005-1022.

(2) Hawkins RE, Malone JD, Cloninger LA, Rozmajzl PJ, Lewis D, Butler J, Cross E, Gray S, Hyams KC. Risk of viral hepatitis among military personnel assigned to US Navy ships. J Infect Dis. 1992 Apr;165(4):716-9. doi: 10.1093/infdis/165.4.716. PMID: 1552201.

[3] Hansen HL. Occupation-related morbidity and mortality among merchant seafarers with particular reference to infectious diseases. Esbjerg: South Jutland University Press, 1996.

[4] Robert Koch Institut. Lamshöft M, Schlaich C. Riegelungsimpfungen gegen Hepatitis A auf einem Frachtschiff. Bericht aus der Tätigkeit des Hafen- und Flughafenärztlichen Dienstes. Epid Bull 2008;(39):338-339.

(5) Mouchtouri VA, Lewis HC, Hadjichristodoulou C; EU SHIPSAN ACT Joint Action Partnership. A Systematic Review for Vaccine-Preventable Diseases on Ships: Evidence for Cross-Border Transmission and for Pre-Employment Immunization Need. Int J Environ Res Public Health. 2019;16(15):2713. Published 2019 Jul 30. doi:10.3390/ijerph16152713

Hepatitis E

Hepatitis E infection is associated with travel to tropical or subtropical countries. It was first recognized 1980 as a cause of human disease. It can be an asymptomatic infection or induce clinical hepatitis, which may be severe or life-threatening, particularly for pregnant women. It is usually transmitted by the oral –faecal route with an incubation period of 15-60 days.

No reports on risk of hepatitis E infection in seafarers have yet been published.

In 2008, acute hepatitis E infection was confirmed in 4 passengers returning to the UK after a world cruise. A contact investigation of 2850 passengers revealed that 25% persons that provided blood samples were hepatitis E seropositive. Crew members were not examined, but the data pointed to a common source foodborne outbreak on board (1)

Another travel related outbreak wirth Hepatitis E was described in a German group of n= 5 (out of 24) travelers returning from India (2)

(1)  Said B, Samreen I, Kafatos G et al. Hepatitis E outbreak on a cruise ship. Emerging Infectious Dis 2009, Vol 15, No 11.

(2) Pischke S, Schulze-Zur-Wiesch J, Lütgehetmann M, Kreuels B, Lueth S, Kapaun P, Benten D, Schmiedel S, Sterneck M, Lohse AW, Polywka S. High clinical manifestation rate in an imported outbreak of hepatitis E genotype 1 infection in a German group of travellers returning from India. Ann Hepatol. 2017 Jan-Feb;16(1):57-62. doi: 10.5604/16652681.1226815. PMID: 28051793.

 

Helicobacter pylori

Infection with Helicobacter pylori causes chronic gastritis and ulcer disease. The infection is epidemiologically linked with gastric adenocarcinoma. H. Pylori has an estimated rate of infection of up to 70% in developing countries and up to 20-30% in industrialized countries (1). H. pylori is a common bacterium, humans are the principal reservoir. The prevalence of H. pylori infection varies widely by geographic area, age, race and ethnicity.  Rates appear to be higher in developing than in developed countries, with most of the infections occurring during childhood, and they seem to be decreasing with improvements in hygiene practices. Overall, inadequate sanitation practices, low social class, and crowded or high-density living conditions seem to be related to a higher prevalence of H. pylori infection.  Recent studies in the United States have linked clinical H. pylori infection with consumption of H. pylori-contaminated well water (2).

There are few studies that evaluated the risk of H. pylori transmission on ships.

In a study to elucidate the route of transmission for Helicobacter pylori 64 German submarine crews who were investigated in comparison to air force staff showed a significantly higher antibody response. Crowding and limited sanitation aboard submarines seemed to facilitate person-person spread among crew members (3).

The prevalence of H. pylori in the crews of United States Navy nuclear submarines was 9.4% (47/451). The authors found this to be comparable to the United States general population (4).

Certainly these data support the importance of proper hygiene and living conditions on ships. The most likely mode of H. pylori transmission is from person to person, by either the oral-oral route (through vomitus or possibly saliva) or perhaps the faecal-oral route. The person-to-person mode of transmission is supported by the higher incidence of infection among institutionalized children and adults and the clustering of H. pylori infection within families. Waterborne transmission, probably due to faecal contamination is possible. As with many other infectious risks on ships, general food and water hygiene and avoidance of crowding on ships is effective to prevent disease transmission.

[1] Heyman DL ed. Control of Communicable Diseases Manual. American Public Health Association. WHO. 19th Edition 2008. ISBN 0-87553-034-6.

(2) Brown LM. Helicobacter pylori: epidemiology and routes of transmission. Epidemiol Rev. 2000;22(2):283-97. doi: 10.1093/oxfordjournals.epirev.a018040. PMID: 11218379.

[3] Hammermeister I, Janus G, Schamarowski F, Rudolf M, Jacobs E, Kist M. Elevated risk of Helicobacter pylori infection in submarine crews. Eur J Clin Microbiol Infect Dis 1992;11:9-14.

[4] Jackman RP, Schlichting C, Carr W, Dubois A. Prevalence of Helicobacter pylori in United States Navy submarine crews. Epidemiol Infect 2006;134:460-464.

 

Enterotoxigenic E. coli

Enterotoxigenic E. coli (ETEC) is a common cause of travel associated diarrhoea.

In a review from the Word Health Organization 21 waterborne outbreaks were associated with ships. Enterotoxigenic E. coli was the pathogen most frequently associated with outbreaks. Contributing factors include contaminated source water, and failure in the disinfection system. No information on involvement of crew was given. Daniels et al. (1) investigated outbreaks of gastroenteritis caused by ETEC on three cruise ships. Attack rates in the first cruise was 2.6% in crew, 7.1% in passengers, in the second cruise 0.25% for crew and 2.5 % in passengers and in the 3rd cruise 2% for crew and 31% in passengers. Water taken in overseas ports was the likely source of disease (2).

In A Navy ship following a visit to Lima, Peru a conczúrrent outbreak of Borovirus and ETEC was described, n=65 out of 230 crew members fell sick. 

[1] Daniels NA, Neimann J, Karpati A, Parashar UD, Greene KD, Wells JG, Srivastava A, Tauxe RV, Mintz ED, Quick R. Traveler´s diarrhea at sea: Three outbreaks of waterborne enterotoxigenic Escherichia coli on cruise ships. J Infect Dis 2000;181:1491-1495.

(2) Gonzaga VE, Ramos M, Maves RC, Freeman R, Montgomery JM. Concurrent outbreak of norovirus genotype I and enterotoxigenic Escherichia coli on a U.S. Navy ship following a visit to Lima, Peru. PLoS One. 2011;6(6):e20822. doi: 10.1371/journal.pone.0020822. Epub 2011 Jun 21. PMID: 21713034; PMCID: PMC3119660.

 

Shigella spp.

Outbreaks with Shigella – particular S. flexneri – are well documented from cruise and other ships. On a cruise from California to Mexico in 1994, 14% (72/512) of passengers and 3% (12/388) of crew fell ill.(1)

(1) Lew JF, Swerdlow DL, Dance ME, Griffin PM, Bopp CA, Gillenwater MJ, Mercatante T, Glass RI An outbreak of shigellosis aboard a cruise ship caused by a multiple-antibiotic-resistant strain of higella flexneri. Am J Epidemiol 1991;134:413-420.

 

Vibrio cholerae

Cholera is an acute diarrhoeal infection caused by eating or drinking food or water that is contaminated with the bacterium Vibrio cholerae.

It takes between 12 hours and 5 days for a person to show symptoms after consuming contaminated food or water. The main manifestation of cholera is severe, very watery (rice-water) diarrhoea, not accompanied by fever that can cause dehydration. However, most infections in healthy adults are inapparent or mild (90%). Most people infected with Vibrio cholerae do not develop any symptoms, although the bacteria are present in their faeces for 1-10 days after infection.

No severe disease was described in seafarers in the last decades. Cholera is often predictable and preventable. It can ultimately be eliminated where access to clean water and sanitation facilities is given.

Effective vaccines are available. Cholera is nit a mandatory or recommended vaccination for seafarers,  unless there are special circumstances (e.g, sewage work in affected aresas, refugee work etc.).

 

Salmonella spp

Other agents of waterborne or foodborne disease including Salmonella typhi and non-typhi, Cryptosporidium, Vibrio parahaemolyticus, Entamoeba histolytica, Yersinia enterocolitica and Giardia lamblia in passengers of cruise ships are documented, but no data are available for risk of infection in seafarers.

Though no data are published on salmonellosis in seafarers, the infection is of special relevance to the seafaring profession. It is a bacterial disease commonly manifested by acute enterocolitis, with sudden onset of headache, abdominal pain, diarrhoea, nausea and sometimes vomiting. Fever is almost always present. It can also cause severe sepsis. In cases of enterocolitis, faecal excretion usually persist for several days or weeks beyond the acute phase, administration of antibiotics may not decrease this duration.

Salmonellosis is commonly transmitted by food of animal origin. The incubation period is usually 12-36 hours.  Cases may occur sporadically or in outbreaks, commonly from contaminated food or water.

If an outbreak aboard a ship occurs, the water system must inspected, including sampling.  Food handling aboard needs to be critically reviewed.

Basic food handling hygiene for eggs and egg products, milk, meat and poultry is important. Appropriate training of the ship´s cook and trusted sources of food in ports aboard are key. All food handlers aboard must be educated about the importance of hand washing before, during and after food preparation, in thoroughly cooking all food stuff from animal sources, and avoiding recontamination within the kitchen after cooking is completed.  Maintaining a sanitary kitchen and protecting prepared food against rodent and insect contamination are also essential pars of this education.

The source of infection may also be an infected food handler. Thus the cooks must be instructed to report symptoms of enterocolitis. The shipmaster MUST exclude the cook and other helpers who have symptoms of diarrhea and vomiting from food handling.  

Typhoid Fever (Enteric Fever, Typhus abdominalis) and Paratyphoid Fever

Typhoid and paratyphoid fevers are systemic bacterial diseases caused by two closely related bacteria of the Salmonella group. The clinical picture varies from mild illness with low-grade to severe clinical disease with abdominal discomfort and multiple complications. The disease occurs worldwide, but most of the burden of the disease is in the developing world. Reservoirs are humans. Transmission is by ingestion of contaminated food or water. Incubation time usually is 8-14 days.

Preventative measures, as with other salmonella infections, concern general hygiene, water treatment aboard and food handling.

Few patients become chronic carriers of typhoid organisms. Typhoid carriers should be excluded from handling food until three consecutive negative cultures are obtained from faecal specimens at least 1 months apart and at least 48 hours after antimicrobial therapy has stopped. Ciprofloxacin treatment 400 mg twice daily for a full month is successful in treating most carriers.

A vaccine for typhoid fever is available and recommended for seafarers from non-endemic areas, especially food-handlers. Persons from endemic areas carry a relatively~ specific immunity after childhood infection.

G.3 Risk based approach to managment of infectious diseases

Details

Skin infection and infestations

Wounds are common in seafarers and they can easily become infected in the marine environment and present as impetigo, carbuncles, furuncles, cellulitis, otitis externa and skin abscesses. Dahl emphasizes that most wounds in seafarers must be considered contaminated, with antibiotic treatment started immediately in hand and puncture wounds and if cellulitis occurs. Pre-sea tetanus immunization is essential (1).

Methicillin-resistant staphylococcus aureus

The occurrence of methicillin-resistant Staphylococcus aureus (MRSA) is a recognized cause of nosocomial infection related to the use of antibiotics and poor hygiene practices. Clinical infection is associated with increased morbidity and mortality. Lately, the infection was reported as the cause of community acquired skin infections in individuals without established risk factors. The US Centers for Disease Control name the five C´s of MRSA transmission as follows: crowding, frequent skin-to-skin contact, compromised skin integrity, contaminated items and surfaces and lack of cleanliness (2).

As ashore, MRSA is an emerging medical challenge on ships:

Outbreaks of community acquired MRSA are reported from day-care centres, military quarters, sport-teams and from ships. La Mar et al describe skin infections in two Navy soldiers; 125 mates from the same living quarters on board were examined with nasal swabs, of which 6.4% were asymptomatic MRSA carriers (3).

Lucas et al. performed a chart review on all consultations to the telemedical advice service at George Washington University in the United States of America from the years 2002 to 2006 (4). Their analysis showed that 36% of skin infections in the year 2002 and 74% of skin infections in the year 2006 were clinically suspicious for infection with methicillin-resistant Staphylococcus aureus. They conclude that the number of skin infections reported to their service has increased during the study period and that the proportion of cases with features common to MRSA infection had doubled.  No studies are available on the prevalence of the infection and/or colonization in patients and staff of ship hospitals in passenger ships.

The relevance of global travel and transport as vectors of Methicillin-resistant Staphylococcus aureus strains has not been studied so far. In 1993 a tourist returning from travel and medical care in India introduced the resistant strain into British Columbia, Canada which spread to several hospitals and caused 12 cases of disease and 14 colonisations (5). MRSA prevalence in resource-limited countries in Asia and Africa and in the seafarer´s population is ill-defined. 

The current evidence suggests that in relapsing or extensive skin infections in seafarers’ methicillin resistant staphylococcus aureus must be considered as a causative agent.

Microbiological resistance testing from wound material should be done whenever possible. In relapsing or extensive infections broad spectrum antibiotics covering MRSA may be justified. Transmission of MRSA among crew is possible. General hygiene measures and precautions in wound care (gloves, hand disinfection) apply.

In 2013 Lekkerkerk described seafarers as a new risk group for methicillin-resistant Staphylococcus aureus (MRSA)’ following their survey of 124 seafarers admitted to the port hospital of Rotterdam in the Netherlands. Screening data showed a prevalence of 5,8% (6).

The relevance of global travel and transport as vectors of MRSA strains has not been studied systematically so far. However case reports suggest that international travel plays a significant role in the transmission of MRSA, potentially contributing to the replacement of existing endemic MRSA with fitter and more transmissible strains (7).  

MRSA prevalence in resource-limited countries in Asia and Africa and in the seafarer´s population is ill-defined. 

The current evidence suggests that in relapsing or extensive skin infections in seafarers, methicillin resistant staphylococcus aureus must be considered as a causative agent. Microbiological resistance testing from wound material should be done whenever possible. In relapsing or extensive infections broad spectrum antibiotics covering MRSA may be justified. Transmission of MRSA among crew is possible. General hygiene measures and precautions in wound care (gloves, hand disinfection) apply.

[1] Dahl E. Wound infections on board ship-prevemtiom, pathogens, and treatement. Int Marit Health 2011; 62, 3: 160-163.

[2] DeLeo FR, Otto M, Kreiswirth BN, Chambers HF. Community –associated methicillin-resistant Staphylococcus aureus. Lancet 2010; 375:1557-156.

(3) LaMar JE, Carr RB, Zinderman C, McDonald K. Sentinel cases of community-acquired methicillin-resistant Staphylococcus aureus onboard a naval ship. Mil Med. 2003 Feb;168(2):135-8. PMID: 12636142.

[4] Lucas R, Boniface K, Roberts K, Kane E. Suspected methicillin-resistant Staphylococcus aureus infections at sea. Int Marit Health 2007;58:93-102.

[5] Roman RS, Smith J, Walker M, Byrne S, Ramotar K, Dyck B, Kabani A, Nicolle LE. Rapid geographic spread of a methicillin-resistant Staphylococcus aureus strain. Clin Infect Dis 1997;25:698-705.

(6) Lekkerkerk WS, van Genderen PJ, Severin JA, Peper JP, Storm EF, Vos MC. Letter to the editor: seafarers: a new risk group for meticillin-resistant Staphylococcus aureus (MRSA). Euro Surveill. 2013 Oct 24;18(43):20618. doi: 10.2807/1560-7917.es2013.18.43.20618. PMID: 24176620.

(7) Zhou YP, Wilder-Smith A, Hsu LY. The role of international travel in the spread of methicillin-resistant Staphylococcus aureus. J Travel Med. 2014 Jul-Aug;21(4):272-81. doi: 10.1111/jtm.12133. Epub 2014 Jun 3. PMID: 24894491.

Other (parasitic) skin infections (e.g. Scabies, Tinea corporis, bed bugs, fleas, infected insect bites)

No further publications on seafarers were found concerning infections which are reported to occur in international short and long term travellers and immigrants, such as impetigo, scabies, pediculosis and infected insect bites, fungal infection or rare skin diseases like leprosy and cutaneus diphtheria.

Despite the lack of published data to this topic, every practising port and ship physician is well aware of the relevance of fungal skin infections, that can easily be treated by hygiene measures and topical ointment: mainly tinea corporis (ring-worm), tinea pedis (athlete´s foot), tinea cruris (jock itch).  

The author has consulted several sipping companies on pest treatment in ships infested with bed bugs and fleas which put a high burden of discomfort to the crew and cost to the shipowner. There are simple measures to prevent bugs and fleas, such as reducing clutter, cleaning luggage before storing in your cabin and frequent vacuum-cleaning

G.1 Introduction

Details

CLARA SCHLAICH

Introduction

It has long been recognized that the occurrence of infectious diseases in seafarers is strongly related to working and living at sea. During the current COVID-19 pandemic seafaring was heavily affected not only by the burden of diseases secondary to SARS-COV2 outbreaks on board, but even more so by travel restrictions, strict quarantine measures, lack of access to leisure facilities in ports, general treatment, lack of oxygen, testing and vaccination. Seafarers suffered of mental stress, anxieties and precarious life and family situations.

Maritime physicians need to follow global infectious diseases trends, understand the epidemiological factors affecting infection and transmission on board, the cultural needs of the seafarers and ensure that all regulatory requirements at ports are met.

When advising, health practitioners must keep in mind the features of the workplace, for example, the seafarer’s rank, the ship´s route, flag, size, cargo and the construction of the vessel. Seafarers experience wide variations in living quarters, food, air and water supply. The composition of crew and contact with passengers and with onshore workers also influence the risk of infections. A useful resource to follow global immunization schemes in international seafarers is provided by WHO (1).

The maritime physician needs to be aware that infectious diseases may pose a threat not only to seafarers, passengers, but also to the public health in ports and home countries. Legal notification requirements must be observed. However, risk perceptions may vary widely and be guided by political or economic goals, thus infections control measures often restrict the free movement of seafarers in port areas without appropriate scientific evidence. The focus of the maritime physicians is to protect the seafarer´s health and safety, laid out by international legislation (International Maritime Convention 2006). In doubt, turn to responsible bodies in your port, such as the International Trade Federation (2) or to a port welfare organizations (3). 

(1) https://apps.who.int/immunization_monitoring/globalsummary

(2) https://www.itfseafarers.org/en/your-rights

(3) https://icma.as/

Sources of Data

Travel related disease may either result from person-to-person transmission of infectious agents or through vectors such as food, water or mosquitoes on board ships or in ports, as well as from a pre-existing condition. Many, but not all, infectious diseases which have been described in travellers are seen in seafarers as well. This may be due to the fact that more studies are undertaken in travellers than in seafarers but risk patterns may differ.

Equally, the magnitude of infectious disease occurrence in seafarers as an occupational group is ill defined due to several challenges for researchers. The global population of seafarers cannot, by the nature of the profession and organization of the international and national shipping fleet, be described and studied as such. Seafaring includes many different working environments, such as fishing, navy ships, ferries, cargo ships and many others. Also, employers give seafarers contracts with varying durations. Ships under the management of one country may be registered under a different flag and acquire personnel from a crewing agency in another country. Hence there is no single source which can be referred to for information on infectious disease morbidity and mortality for any specific population of seafarers.

Common study designs

Common study types concerning infectious diseases in shipping include:

  • Longitudinal studies
    • medical log books
    • surveillance networks
    • seafarers national insurance data
    • navy registers
  • Cross-sectional studies
    • pre-employment exams
    • data from port medical services or welfare centres
    • telemedical consultations
    • cross-sectional investigations on board
  • Case studies – reviews
    • investigations by health authorities
    • treatment reports and port doctors

While all of these sources have the potential to improve knowledge about the frequency and prevention of infections in the maritime sector, few have been analysed in any depth.

With a few notable exceptions, no national or international surveillance systems exist to record infectious disease occurrence on ships. Most national or international surveillance systems for infectious diseases do not collect data on professions in general and seafaring in particular. Most studies on infectious diseases in seafarers are prevalence studies in convenient samples, or case and outbreak reports. A further source of bias is the fact that only a few research groups on maritime health exist globally. Most of them are in European countries, for example, the UK, Denmark, Poland and Germany. These traditional maritime nations, while they have active maritime sectors, no longer supply the majority of personnel to the modern shipping industry

Epidemiological studies are commissioned for a defined purpose. Different interests drive the research and guidelines concerning infections on board of ships. Understanding of the sources of data on infectious diseases in seafarers is needed to draw correct conclusions and give valid advice. While medical care on board and in ports and considerations of ship safety are closely interconnected, research activities also focus on controlling risks to public health from the shipping industry.

Table 1 shows the areas of interest which have driven legislation and research efforts on infectious diseases in seafaring.

The magnitude of the problem

The epidemiology, prevention and control of infectious diseases differ substantially in different maritime environments, such as cruise ships, cargo ships, military ships, offshore installations and fishing communities.

Historic events concerning maritime spread of plague, cholera, influenza are well described (1) and led to the introduction of maritime quarantine measures, international sanitary conference and currents laws, such as the 2005 WHO International Health Regulations (2).

During the 2010 IMHA workshop on “Infection on board ships in the 21st century” it was emphasized that important aspects of risk and intervention are different for infectious diseases in the maritime sector and for similar conditions arising ashore (3).

Studies that quantify the current risks of infectious diseases in seafarers as compared to the general population are rare. For HIV, Hepatitis B and C or Hepatitis A the prevalence of the disease in the home country is the strongest predictor for occurrence in seafarers and passengers (4).

Accident insurance data and data from maritime authorities have documented the occurrence of infectious diseases such as malaria and tuberculosis, which are commonly recognized as occupational diseases with a relevant travel history or when contact to a case (of tuberculosis) has occurred. Often, these registers underestimate the occurrence of disease due to international crewing practices.

Hansen and co-workers performed a retrospective study based on a national register of all seafarers employed on Danish ships during 1986 to 1993. Infectious diseases were more common among seafarers than in the male Danish population in general. Main causes of death on board of Danish merchant ships were infectious, gastrointestinal, heart diseases and stroke (5).

Also from Denmark, Linda Kaerlev systematically studied time trends in hospital contacts among Danish seafarers and fishermen between 1994 and 2003. She found hospitalization rates for non-officers highest for infectious diseases, fishermen had high hospitalization rates for tuberculosis (15 cases). Alos she described HIV infection among non-officers. (6)

Radiomedical services provide important information on disease activity onboard cargo ships.

Out of 866 cases and 1720 radiomedical contacts in 48 consecutive months from U.S. flagged ships at sea to US emergency medicine physicians for advice, 48% of cases were medical, 14% were injuries and 2% were purely psychiatric. 15% of the medical cases were due to respiratory infections (7).

Data from the radiomedical service in Sweden from 1997, 2002, 2007 and 2009 demonstrated that 33% of all 1290 consultations concerned infections, most often from the respiratory and digestive system. 71% of seafarers completed treatment on board and no further treatment in port or repatriation were necessary (8).

Schlaich et al. showed in a retrospective study based on medical log-books from merchant ships under German flag that during more than 1.5 million person-days of observation from 2002-2008, nearly one fourth of the visits to the ship’s infirmary were due to communicable diseases (45.8 consultations per 100 person-years) (9).

Navy ships provide important insights on infectious disease prevalence and transmission on board, e.g. outbreaks of food-borne disease, respiratory diseases such as Mycoplasma pneumoniae, COVID-19, influenza, tuberculosis, hepatitis A, B and C (10,11,12) and others.

The significance of transmission of gastrointestinal and respiratory diseases in commercial cruise ship is widely recognized for decades. Trough the efforts of the US Vessel Sanitation Program (13) and EU projects such as CDC SHIPSAN ACT, SHIPSAN Trainet and others (14) valide surveillance data are generated and control measures evaluated.

In a 3 year prospective documentation of outbreaks on a cruise ships with 440 passengers and 421 crew members, influenza like illness and acute respiratory illness were the predominant reason for consultation as compared to gastrointestinal disease (15).

The ongoing COVID-10 pandemic is advancing our understanding of respiratory disease transmission on board of ships. Across all types of ships, problems in handling outbreaks resulted from a high number of asymptomatic infections, transportation issues, challenges in communication or limited access to health care (16).

Most currently, a research project “ARMIHN” (Adaptive Resiliency Management in Port) assessed the need to srengthen capacities to act in a mass casualty incident due to an outbreak of infectious diseases on cruise ships in the Port of Hamburg (17).

(1) Carter T. Infections at sea past and present. Int Marit Health. 2011;62(3):157-9. PMID: 22258839.

(2) Hardiman M. The revised International Health Regulations: a framework for global health security. Int J Antimicrob Agents. 2003 Feb;21(2):207-11. doi: 10.1016/s0924-8579(02)00294-7. PMID: 12615388.

(3) Carter T. Infection on board ships in the 21st century: overview of IMHA workshop, Singapore 2010. Int Marit Health. 2011;62(3):160-3. PMID: 22258840.

(4) GBD 2019 Diseases and Injuries Collaborators. Global burden of 369 diseases and injuries in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2020 Oct 17;396(10258):1204-1222. doi: 10.1016/S0140-6736(20)30925-9.

(5) Hansen HL, Henrik Andersen P, Lillebaek T. Routes of M. tuberculosis transmission among merchant seafarers. Scand J Infect Dis. 2006;38(10):882-7. doi: 10.1080/00365540600740512. PMID: 17008232.

(6) Kaerlev L, Jensen A, Hannerz H. Surveillance of hospital contacts among Danish seafarers and fishermen with focus on skin and infectious diseases-a population-based cohort study. Int J Environ Res Public Health. 2014;11(11):11931-11949. Published 2014 Nov 18. doi:10.3390/ijerph111111931

(7) McKay MP. Maritime health emergencies. Occup Med; 2007 Sep;57(6):453-5. doi: 10.1093/occmed/kqm053. Epub 2007 Jul 25. PMID: 17652345.

(8) Westlund K. Infections onboard ship--analysis of 1290 advice calls to the Radio Medical (RM) doctor in Sweden. Results from 1997, 2002, 2007, and 2009. Int Marit Health. 2011;62(3):191-5. PMID: 22258846.

(9) Schlaich CC, Oldenburg M, Lamshöft MM. Estimating the risk of communicable diseases aboard cargo ships. J Travel Med. 2009 Nov-Dec;16(6):402-6. doi: 10.1111/j.1708-8305.2009.00343.x. PMID: 19930380.

(10) Riddle MS, Smoak BL, Thornton SA, Bresee JS, Faix DJ, Putnam SD. Epidemic infectious gastrointestinal illness aboard U.S. Navy ships deployed to the Middle East during peacetime operations--2000-2001. BMC Gastroenterol. 2006 Feb 25;6:9. doi: 10.1186/1471-230X-6-9. PMID: 16504135;

(11) Nir-Paz R. Mycoplasma pneumoniae Outbreaks on Navy Vessels. J Clin Microbiol. 2010 May;48(5):1990; author reply 1990. doi: 10.1128/JCM.00113-10. PMID: 20444984; PMCID: PMC2863942.

(12) Kasper MR, Geibe JR, Sears CL, Riegodedios AJ, Luse T, Von Thun AM, McGinnis MB, Olson N, Houskamp D, Fenequito R, Burgess TH, Armstrong AW, DeLong G, Hawkins RJ, Gillingham BL. An Outbreak of Covid-19 on an Aircraft Carrier. N Engl J Med. 2020 Dec 17;383(25):2417-2426. doi: 10.1056/NEJMoa2019375. Epub 2020 Nov 11. PMID: 33176077; PMCID: PMC7675688.

(13) Jenkins KA, Vaughan GH Jr, Rodriguez LO, Freeland A. Acute Gastroenteritis on Cruise Ships - Maritime Illness Database and Reporting System, United States, 2006-2019. MMWR Surveill Summ. 2021 Sep 24;70(6):1-19. doi: 10.15585/mmwr.ss7006a1. PMID: 34555008; PMCID: PMC8480991.

(14) Hadjichristodoulou C, Mouchtouri VA, Martinez CV, Nichols G, Riemer T, Rabinina J, Swan C, Pirnat N, Sokolova O, Kostara E, Rachiotis G, Meilicke R, Schlaich C, Bartlett CL, Kremastinou J, Partnership TS. Surveillance and control of communicable diseases related to passenger ships in Europe. Int Marit Health. 2011;62(2):138-47. PMID: 21910118.

(15)  Pavli A, Maltezou HC, Papadakis A, Katerelos P, Saroglou G, Tsakris A, Tsiodras S. Respiratory infections and gastrointestinal illness on a cruise ship: A three-year prospective study. Travel Med Infect Dis. 2016 Jul-Aug;14(4):389-97. doi: 10.1016/j.tmaid.2016.05.019. Epub 2016 Jun 15. PMID: 27320130.

(16) Kordsmeyer AC, Mojtahedzadeh N, Heidrich J, Militzer K, von Münster T, Belz L, Jensen HJ, Bakir S, Henning E, Heuser J, Klein A, Sproessel N, Ekkernkamp A, Ehlers L, de Boer J, Kleine-Kampmann S, Dirksen-Fischer M, Plenge-Bönig A, Harth V, Oldenburg M. Systematic Review on Outbreaks of SARS-CoV-2 on Cruise, Navy and Cargo Ships. Int J Environ Res Public Health. 2021 May 13;18(10):5195. doi: 10.3390/ijerph18105195. PMID: 34068311; PMCID: PMC815334

(17) Klein A, Heuser J, Henning E, Sprössel N, Kordsmeyer AC, Oldenburg M, Mojtahedzadeh N, Heidrich J, Militzer KC, Belz L, von Münster T, Harth V, Ehlers L, de Boer J, Kleine-Kampmann S, Boldt M, Dirksen-Fischer M, Haralambiev L, Gümbel D, Ekkernkamp A, Bakir MS. A mass casualty incident of infectious diseases at the port of Hamburg: an analysis of organizational structures and emergency concepts. J Occup Med Toxicol. 2021 Aug 31;16(1):36. doi: 10.1186/s12995-021-00324-0. PMID: 34465347; PMCID: PMC8406386.

Epidemiology of maritime infectious diseases

There is great diversity in the clinical patterns of different infections and hence the features of individual infections are discussed, by reference to their main modes of transmission.

G.2 Epidemiology

Details

Blood or bodily fluids cluster

Potential hazards for blood-borne infections and sexually transmitted diseases include accidents and injuries, unsafe medical care provided to seafarers in ports in highly endemic areas, accidental injuries during medical procedures on board, unsafe blood transfusions, tattooing, piercing and unprotected sex.

Seafarers have traditionally been seen as a special risk group for acquiring and spreading sexually transmitted diseases, as indicated by the Brussels International Agreement of 1924 which requires state parties to provide free medical services to merchant seamen for the treatment of syphilis, urethritis of any aetiology, chancroid, lymphogranuloma venereum, granuloma inguineale and any other venereal diseases (1).  

In 1993 the common committee of the International Labour Organization and the World Health Organization identified Hepatitis B and Human Immunodeficiency Virus Infection / Acquired Immunodeficiency Syndrome as infectious diseases against which there should be provisions for guidance on prevention (2). 

The Maritime Labour Convention 2006 emphasizes the need for HIV/AIDS prevention targeted at merchant seamen (3).

The International Maritime Health Association and the International Trade Federation issued a statement in 2008 in which the organizations advocate against selection for employment based on HIV status (4).

Despite widespread Hepatitis B, C or HIV testing as part of pre-employment examinations, there are no valid data concerning HIV or Hepatitis B /C prevalence in seafarers.

[1] World Health Organization. International Agreement of Brussels 1924. In: World Directory of Veneral Disease Treatment Centres at Ports. 3rd ed. Geneva: WHO, 1972.

[2] International Labour Organization. Joint ILO/WHO Committee on the health of seafarers. Seventh session. Geneva, 10-14 May 1993. Report. Geneva: ILO, 1993. (JCHS/7/D (Rev.).

[3] International Labour Conference. Maritime Labour Convention 2006. Geneva: ILO, 2006-. https://www.ilo.org/global/standards/maritime-labour-convention/lang--en/index.htm, last access 14.2.2022

[4] The International Transport Workers’ Federation. Challenging HIV/AIDS in transport. Parris K, ed. Agenda 2008;(2). https://www.itfglobal.org/media/819789/hiv_survey.pdf, last access 14.2.2022

Risk assessment

Potential hazards for the spread of blood-borne infections and sexually transmitted diseases include:

  • accidents and injuries,
  • unsafe medical care provided to seafarers in ports in highly endemic areas,
  • accidental injuries during medical procedures on board,
  • unsafe blood transfusions,
  • broken skin and skin lesions
  • tattooing, piercing and
  • unprotected sex.

Risk management

There is a marginal risk of transmission of blood-borne diseases from living and working together on a ship. However, medical care and first aid pose more specific risks of transmission from possible blood contact. Consequently, in the individual risk assessment at a PEME, and during the pre-travel counselling of seafarers, several risk factors for acquiring such infection need to be addressed:

  • Risk of infection during first aid and medical care by nautical officers on board,
  • Risk of nosocomial infection from unsafe blood products and a variety of medical procedures (injections, dental care, endoscopy, surgery etc.) in port medical facilities
  • Unprotected sexual intercourse
  • Piercing and tattooing

Additional steps can also be taken that include:

  • the use of personal protective equipment, for example gloves when administering first aid and medical care on board
  • safe disposal of sharps and other medical waste on board
  • careful choice of location and type of medical care received ashore if possible
  • continuous information on the risks of unprotected commercial or other sex, possibly accompanied by the free availability of condoms on board

These are the responsibility of the ship owners/operators and can reduce the risk of infection with Hepatitis B and C along with HIV and other infections.

The international Trade Federation provides information to seafarers:

https://www.itfseafarers.org/en/health/hepatitis-b

https://www.itfseafarers.org/en/health/hivaids

Hepatitis B virus

Hepatitis B virus (HBV) infections occur worldwide with transmission through infected blood, saliva and semen. One third of the world’s population is infected. The majority of acute Hepatitis B infections remain asymptomatic although 30-50% of adults present with an acute illness with jaundice, fever and abdominal pain. The incubation period is usually 45 to 180 days and all individuals who are HbsAg positive are potentially infectious.

Transmission occurs by percutaneous (intravenous, subcutaneous, intramuscular, intradermal) and mucosal exposure to infective body fluids. Major modes of HBV transmission include sexual or close household contact with an infected person, perinatal mother-to-infant transmission, injecting drug use, piercing and tattooing and nosocomial transmission. The case fatality rate is about 1%, but higher in those over 40 years of age. In a small fraction of adults infected with HBV, a chronic illness with severe complications such as liver cirrhosis, liver failure and hepatoma develop after decades.

A recombinant vaccine is available which protects from acute and chronic infection and is recommended by the World Health Organization for at-risk groups and for inclusion in childhood vaccine schedules.

HBV in seafarers

Available studies do not allow estimates if seafaring is a risk factor for Hepatitis B infection.

Differences in population of seafarers mainly reflect the prevalence of Hepatitis B infection in the country of origin and the availability of routine immunization in the home country of the seafarer. As an example: The prevalence of chronic Hepatitis B in the Philippines was 16,7% in the year 2016 (1).

A study of 2072 male United States naval personnel done in 1989 showed that the prevalence of the hepatitis B marker anti-HBc in military personnel was comparable to that in a concurrent survey of the United States civilian population. Presence of anti-HBc was independently associated with age, black or filipino race, foreign birth, a history of sexually transmitted disease and South Pacific / Indian Ocean deployment (2).

A retrospective longitudinal study from a Danish research database containing all seamen who had been employed on Danish ships between 1986 and1993  and the National Registry for Notifiable Diseases found that the standardised incidence ratio for  hepatitis B Virus infection among male sailors compared to the general population was 3.2 (95% CI:1.79-4.78). The main mode of transmission was intravenous drug use (3).

Bellis and co-workers in a prevalence study conducted among sailors arriving at the port of Liverpool in the United Kingdom found a 12 % prevalence of the hepatitis B marker anti- Hbc among a study population of 291 sailors. Sailors from Asia had a higher prevalence of seropositivity when compared with colleagues from Western Europe, and North America (4).

A clinic based prevalence study from Spain in 1998 assessed 2348 seafarers attending health clinics who were examined for evidence of hepatitis. Out of the 98 symptomatic cases 50 (2.1% of study population) carried anti- HBc-, signifying contact to hepatitis B Virus during their lifetime (5).

A cross sectional study conducted among 95 Vietnamese civilian and military seafarers and 45 other maritime workers in the city of Haiphong showed that 58% (55/140) persons in the study population were positive for HBsAg and Anti-HBs. The authors concluded that Vietnamese seamen are a high risk group for hepatitis B infection (6).

A survey of 103 seafarers attending a training course for medical care on board in Denmark showed that the seamen responsible for medical care on board in the absence of a medical doctor do have a risk of exposure to blood and body fluids. Over a 10-year period 19 out of 103 persons reported contact with blood, including 4 accidents with needles, 23 persons had been in contact with other body fluids and hence at a potential risk of infection (7).

In Georgia, a nation that supplies a large number of seafarers to the global market, hepatitis B virus infection is assessed as part of the pre-employment exams. It was found that 6.5% of 1165 male Georgian seafarers were tested positive for HBs Antigen (8).

Overall, available studies do not allow estimates to be made to show whether seafaring is associated with a higher risk of hepatitis B infection. The results mainly reflect the epidemiology of hepatitis B infection and availability of routine immunization in the country of origin of the seafarer.

Chronic hepatitis B infection with no signs (clinical and lab studies) of hepatic impairment and a confirmed low level of infectivity should not restrict a seafarers’ fitness to work (9).

If a chronic hepatitis B infection is accidentally detected during the pre-employment exam, the clinician will have to counsel the patient on further diagnostic and treatment options. The urgency of diagnostic and possibly therapeutic requirements depend on factors including  liver function and the availability of therapy in the country (10).

All seafarers positive for Hepatitis BsAg are potentially infectious, the level of infectivity varies with the viral load. Chronic Hepatitis B infection with no clinical or laboratory evidence of hepatic impairment and a confirmed low level of infectivity should not restrict a seafarers’ fitness to work. If a chronic Hepatitis B infection is detected incidentally during the pre-employment medical examination (PEME), the clinician will have to counsel the patient on further diagnostic and treatment options. The urgency of diagnostic and possibly therapeutic requirements depends on many factors including liver function and the availability of therapy in the country.

Beyond any doubt first aid and medical in the shipping environment is an occupational risk for hepatitis B infection. Full pre-travel immunisation of all seafarers against Hepatitis B is strongly recommended (3x vaccination against Hepatitis B) if not included in the childhood scheme of the respective country.  

(1) Gish RG, Sollano JD Jr, Lapasaran A, Ong JP. Chronic hepatitis B virus in the Philippines. J Gastroenterol Hepatol. 2016 May;31(5):945-52. doi: 10.1111/jgh.13258. PMID: 26643262.

(2) Hawkins RE, Malone JD, Cloninger LA, Rozmajzl PJ, Lewis D, Butler J, Cross E, Gray S, Hyams KC. Risk of viral hepatitis among military personnel assigned to US Navy ships. J Infect Dis 1992;165:716-719.

(3) Hansen HL, Hansen KG, Andersen PL. Incidence and relative risk for hepatitis A, hepatitis B and tuberculosis and occurrence of malaria among merchant seamen. Scand J Infect Dis 1996;28:107-110.

(4) Bellis MA,Weild AR, Beeching NJ, Syed Q. Sexual behaviour and prevalence of antibodies to HIV and hepatitis B seafarers visiting Liverpool. J Infect 1996;32:73.

(5) Cerdeiras MJ, Fontenla ME, Romero B. Morbilidad por Hepatitis B en la gente del mar. In: Asociacion Medica Espanola de Sanidad Maritima, ed. I. Congreso Nacional de Medicina del Mar. Tarragona, 1, 2 y 3 de noviembre 1990. Santander 1991:85-89.

(6) Duc Lung N, Son, NT, Thuc PV. Preliminary investigation of HBV incidence in the seamen and other maritime workers in Hai Phong City of Viet Nam. In: The Norwegian Association for Maritime Medicine; The Norwegian maritime directorate, eds. The Fourth International Symposium on Maritime Health. Oslo June 21 to 25 1997. Abstracts. Oslo 1997:12-14.

(7)  Nilaus S. Medics’ risk of exposure to infection with hepatitis B. In: 9th International Symposium on Maritime Health. Equity in maritime health and safety – development through research, cooperation and education. Book of Abstracts. Esbjerg, Denmark 3-6 June 2007. Poster 1-12.

(8) Tchkonia G, Akhvlediani. HBV spreading among seafarers and humoral immunity indexes of HBsAg carriers. In: 9th International Symposium on Maritime Health. Equity in maritime health and safety – development through research, cooperation and education. Book of Abstracts. Esbjerg, Denmark 3-6 June 2007. Paper 5-2.

(9) International Labour Organization. International Maritime Organization. 2011.  Proposed revised Guidelines on the medical examinations of seafarers.  ISBN: 978-92-2-125096-8 (print), ISBN: 978-92-2-125097-5 (Web pdf)

(10) Carter T 2013. Handbook for seafarer medical examiners. http://handbook.ncmm.no/index.php/infections-transmitted-in-body-fluids-hepatitis-non-a (last access 1.10.2013

 

Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome (HIV/AIDS)

Acquired Immunodeficiency Syndrome (AIDS) is caused by Human Immunodeficiency Viruses 1 and 2 (HIV 1/2) which damage the immune system and make an affected person more vulnerable to infections and to other diseases such as cancer.

AIDS is recognized to be a major public health problem throughout the world. It is now known that the patterns of the epidemic differ between regions. In some parts of the world, such as North America, Europe or the Philippines it mainly affects certain risk groups such as intravenous drug users, immigrants or homosexuals but is also a threat to the general population. In other parts of the world, such as Central, Eastern and Southern Africa and some countries of the Caribbean it is primarily seen in heterosexuals. Countries and regions such as Eastern Europe, China or India are facing new public health challenges due to HIV.

HIV is present in the majority of body fluids of an infected person. Most infections result from contact with semen and vaginal secretions or blood and blood products from a person infected with the virus. HIV cannot be transmitted through social or workplace contact with an infected person and there are no documented cases of transmission through kissing.

In the last decade, the risk of infections through different sexual practices has been studied in detail, showing that the often cited value of 0.001 transmissions per 1000 contacts represents a lower estimate with a high variability due to transmission cofactors such as circumcision or genital ulcer disease. While the risk of disease transmission is highest in the early stages of infection, treatment of the disease with successful lowering of the viral load is now recognized as a powerful public health tool that reduces the risk of transmission.

Cure of HIV infection is not possible, but effective treatment options for HIV infection have existed for more than a decade and new ones are constantly being introduced. For most persons to whom this treatment is available, HIV has turned from an acute into a chronic condition. This requires life-long adherence to antiviral medication. The infected persons will usually be perfectly well for several years after infection. During this time the CD 4 count, a marker of infection, will decline slowly over the years. However latency time from infection to the point when treatment is needed is highly variable due to genetic factors, exposure to infections and general living conditions. In general, treatment starts when damage to the system has reached a potentially dangerous level. Strict adherence to therapy and close monitoring of side-effects and immune-status by a specialist are essential for a successful outcome.

8.1.5.1     Work related risk of HIV infection in sailors

Mobile transport workers, mainly truck-drivers, played a major role in spreading the disease in Africa and India in the evolving global pandemic. Very early in the epidemic HIV/AIDS affected the community of seafarers. Later analysis of blood samples taken during the course of disease revealed that as early as the 1950´s an English seafarer died of AIDS (1).

Hansen et al estimated the risk of HIV infection in seafarers by an analysis of medical records from the main HIV treatment centres in Denmark. The risk of HIV infection in seafarers was estimated in comparison to the general Danish population up to the end of 1992. The incidence of HIV infection for Danish seafarers was estimated to be 0.000016 cases/person-year. This was eight times higher than in the general Danish population. The authors found that most infections in seafarers were acquired heterosexually early in the epidemic in high-endemicity areas (2).

A study published in 1992 conducted among a sample of 561 Spanish seafarers seeking attention prior to travelling abroad confirmed HIV-1 infection in 4% of seafarers (3).

A questionnaire survey from Croatia performed in Rijeka in 1989 to 1990 demonstrated that seafarers had inadequate knowledge about the routes of HIV transmission and rarely used condoms for protection against HIV infection (4).

2 positive cases of HIV in African seafarers visiting a port in Belgium were identified among 599 sailors in the early nineties (5).

Demissie and co-workers reported 1996 in a cross-sectional study in 260 Ethiopian sailors found an HIV-1 prevalence of 9.6%  as assessed by blood-testing (6)

A study from Poland analyzed serological HIV tests from 1992 to 1996. From 26,988 tests performed in seafarers HIV antibodies were detected in 11 seamen and 3 deep-sea fishermen (0.05%) (7).

Bellis and co-workers performed saliva testing for HIV antibodies in 304 sailors whilst in Liverpool, United Kingdom. A 0.33% prevalence of anti-HIV was reported (8).

In the Philippines a questionnaire was handed to seafarers who presented at manning agencies from August 1997 to March 1998. The results showed that 52% of 300 respondents admitted extramarital sexual encounters (9). A 2005 report from the Department of Health of the Philippines, which supplies the largest number of seafarers of any country globally, analysed 2250 HIV positive cases. 745 were Filipino overseas workers including 36% seafarers. The main mode of transmission was sexual (10).

An analysis of the central register of HIV/AIDS infections from Montenegro in 2007 indicated that 15% of the total of 68 notified HIV infected persons in Montenegro were seafarers by profession. It is suggested that there are about 6000 professional seafarers in Montenegro (11).

Local fishing communities have been identified as among the highest-risk groups for HIV infection in countries with high overall rates of HIV/AIDS prevalence, such as Brazil, Cambodia, Congo, Malaysia, Myanmar, Thailand and Uganda. Vulnerability to HIV/AIDS stems from the time fishers and fish traders spend away from home, their access to cash income, the ready availability of commercial sex in fishing ports and the sub-cultures of risk taking and hyper-masculinity fishers. There is a concern that fishers, as they get more integrated in the global market may spread HIV to prevalence populations (12,13).

The following risk factors for HIV infection are identified (14):

  • decreased or absence of access to HIV information,
  • barriers to voluntary testing and counselling,
  • likelihood of engaging in risky sexual practices,
  • separation from spouses and families,
  • alcohol use,
  • time spent in high prevalence regions.

In a current review (2020) it was found, that many seafarers had no specific training and only learned about STIs and HIV through media such as television (15).

Recent surveys on HIV prevalence in sailors are not available in the scientific literature.

In the authors experience HIV infection and AIDS are very rare innthe seafaring population. In the cruise ship industry a small number of employees of euripaean, UK or US/Canada origin are HIV positive, all of them are well controlled under antitretroviral therapy and highly informed about their disease and their rights as employees in the maritime industry.

(1) Zhu T, Korber BT, Nahmias AJ, Hooper E, Sharp PM, Ho DD. An African HIV-1 sequence from 1959 and implications for the origin of the epidemic. Nature. 1998 Feb 5;391(6667):594-7. doi: 10.1038/35400. PMID: 9468138.

(2) Hansen HL, Brandt L, Jensen J, Balslev U, Skarphedinsson S, Jørgensen AF, David K, Black FT. HIV infection among seafarers in Denmark. Scand J Inf Dis 1994;26:27-31.

(3) Ollero, M, Merino D, Pujol E, Marquez P, Gimeno A, Angulo C. Tattoos and hepatitis C virus infection. VIII International Conference on AIDS, Amsterdam ,19-24 July 1992. Int Conf AIDS 1992;8:180

(4) Sesar Z, Vlah V, Vukelic M, Cuculic M.Knowledge of seafarers about AIDS problems and their vulnerability to HIV infection. Bull Inst Marit Trop Med Gdynia 1995;46:19-22.

(5) Verhaert P, Damme P, Cleempoel R. Seo-epidemiological study on syphilis, HBV and HIV among seafarers in Antwerp.Proceedings of the second international symposium on maritime health. June 2nd-6th 1993. Antwerpen 1995. p 213-223.

(6) Demissie K, Amre D, Tsega E. HIV-1 infection in relation to educational status, use of hypodermic injections and other risk behaviours in Ethiopian sailors. East Afr Med J. 1996; 73:819-22.

(7) Towianska A, Dabrowski J, Rozlucka E. HIV antibodies in seafarers, fishermen and in other population groups in the Gdansk Region (1993-1996). Bull Inst Marit Trop Med Gdynia 1996;47:67-

(8) Bellis MA,Weild AR, Beeching NJ, Syed Q. Sexual behaviour and prevalence of antibodies to HIV and hepatitis B seafarers visiting Liverpool. J Infect 1996;32:73.

(9) Estrella-Gust DP. Policies and programs on HIV/AIDS. Tripartite paper: Policy and programs on HIV/AIDS. Quezon City: Department of Labor and Employment. Occupational Safety and Health Center. http://www.oshc.dole.gov.ph/page.php?pid=133. Last access August 2013.

(10) Department of Health (DOH), Government of the Philippines. 2005 HIV/AIDS Registry. www.jcie.org. Last access August 2013.

(11) Jovicevic LJ, Vranes-Grujicic M. HIV/AIDS in seafaring population of Montenegro and prevention suggestions. In: 9th International Symposium on Maritime Health. Equity in maritime health and safety – development through research, cooperation and education.Book of Abstracts.Esbjerg, Denmark 3-6 June 2007.Poster 1-11.

(11) Ford K, Chamratrithirong A. Migrant Seafarers and HIV risk in Thai communities. AIDS Education and Prevention, 208(5), 454-463, 2008.

(13) (6) Smolak A. A meta-analysis and systematic review of HIV risk behavior among fishermen. AIDS Care. 2014;26(3):282-91. doi: 10.1080/09540121.2013.824541. Epub 2013 Aug 13. PMID: 23941609.

(14) Nikolic N. AIDS prophylaxis –achievements due to appropriate strategies. Int Marit Health 2011; 62, 3:176-182

(15) Pougnet R, Pougnet L, Dewitte JD, Rousseau C, Gourrier G, Lucas D, Loddé B. Sexually transmitted infections in seafarers: 2020's perspectives based on a literature review from 2000-2020. Int Marit Health. 2020;71(3):166-173. doi: 10.5603/IMH.2020.0030. PMID: 33001427.

8.1.5.2     Employment and HIV/AIDS

The International Labour Organisation has published an “ILO Code of Practice on HIV/AIDS and the World of Work” in 2001 where the organisation advocates for the continuation of employment regardless of HIV status. However, the ship as a work place has always been seen as a special entity due to the limited access to diagnosis and therapy while on board.

Dahl evaluated the workplace policies of cruise ship companies concerning HIV positive crew on ships. He found a variety of practices, about half of the 15 companies responding require pre-sea HIV testing, some to avoid hiring HIV+ seafarers, others to establish HIV as a pre-existing condition or to ensure proper follow up of the HIV infected seafarers (1)

The decision on the fitness of a HIV positive person for duty on board is complex and involves in depth knowledge of the natural course of disease, treatment options and living conditions at sea.  The Handbook for Seafarers´Medical Examiners gives detailed advice on the best means for taking  decisions on fitness to work at sea (2)

The main concern when taking fitness decisions in relation to HIV infection is the access to medication during travel. Risks to other crew members are negligible if HIV viral is undetectable and standard precautionary measures are observed.

(1) Dahl E. HIV positive Crew on Cruise ships. .11th International Symposium on Maritime Health. Book of Abstracts 2010: page 27.

(2) Guidelines on the medical examinations of seafarers / International Labour Office, Sectoral Activities Programme; International Migration Organization. – Geneva: ILO, 2013 ILO/IMO/JMS/2011/12 ISBN 978-92-2-127462-9 (print) ISBN 978-92-2-127463-6 (web pdf)

 

Post-exposure prophylaxis with accidental exposure to blood and other fluids

HIV infection can be prevented after a contact with body fluids from an HIV infected person. Drugs effective against HIV must be given as soon as possible after a risk-exposure to the virus. Post-exposure prophylaxis, if taken correctly reduces the risk of infection by 80%.  

Exposure may occur from accidental exposure to body fluids during medical care and first aid, but also from unprotected sex. For this reason Anti-HIV medication is now recommended by the WHO to be carried as part of the ship’s medical chest (1).

However, no specific recommendations for the best use of post-exposure prophylaxis in the marine environment have been agreed. Most recommendations have been developed for the health care sector or for high risk sexual encounters (such as commercial sex). The use of post-exposure prophylaxis must remain an individualized decision depending on the specific circumstances. It can be safely assumed that the risk for seafarers providing first-aid on board is lower than for health care workers in high prevalence countries. However, unprotected heterosexual or homosexual commercial sex in a high prevalence country (such as South Africa) justifies post exposure prophylaxis. Post-exposure prophylaxis is no substitute for availability of condoms and preventative messages to seafarers.

General rules for the use of antiretroviral post-exposure therapy in an injury during first aid are:

- Immediately remove as much as possible of the body fluid

- If a high-risk exposure is suspected and no medical advice is available start antiretroviral prophylaxis if possible within 2 hours, otherwise consult a medical specialist before the start of treatment. Starting post-exposure prophylaxis more than 72 hours after exposure is not effective and should not be done. Consult a specialized medical doctor or radio-medical advice as soon as possible for continuation of prophylaxis (typically taken for 30 days).

Table 3. Classification of risk of transmission after exposure to HIV

Other Sexually Transmitted Diseases
8-2-1.png

(1) World Health Organization. International medical guide for ships: including the ship´s medicine chest (IMGS). 3rd edition. Geneva: WHO 2007.

 

Hepatitis C infection

Hepatitis C virus infection occurs worldwide. Population seroprevalence differs between low – income countries and high income countries.

The main mode of transmission is via reused or shared injections, piercing or tattooing utensils, contaminated blood products or other material contaminated with blood. Spread of disease by sexual intercourse is less likely. Period of communicability is from one or more weeks before onset of symptoms and may persist in most persons indefinitely.

Onset of the disease is usually insidious with anorexia, vague abdominal discomfort, nausea and vomiting; progression to jaundice is less frequent than with hepatitis B.

Although initial infection may be asymptomatic (more than 90% of cases) or mild, a high percentage of cases (50-80%) develop a chronic infection. About half of those chronically infected persons will eventually develop cirrhosis or cancer of the liver.

No longitudinal studies on the burden of hepatitis C infection in seafarers were identified.

A study published in 1992 conducted among a sample of 561 Spanish seafarers seeking attention prior to travelling abroad confirmed hepatitis C infection in 9% (52/561) of seafarers. Former intravenous drug use and tattooing were found to be independent risk factors for infection with hepatitis C (1).

In a cross sectional study in the United States of n= 2027 Naval military recruits in 1989, the prevalence of hepatitis C virus was found to be 0.4% (9/2072) (2)

A Danish survey among 515 seafarers who sailed in international trade published in 1995 recorded a prevalence of 1.2% antibodies against hepatitis C (3).

In Georgia, Hepatitis C virus infection is routinely assessed as part of the pre-employment exams. It was found that 11.5% (162) of a total of 1400 male Georgian seafarers were anti-HCV positive. Further studies indicated that 157 out of these 162 seafarers had active disease (4).

Medical cards of 270 seamen in Croatia (less than 1% of all approx. 320 000 Croatian seamen) from one general practice in the area of Split were studied in the year 2006 for the presence of hepatitis C infection. Out of 37 test results 8 showed evidence of infection. Documented modes of transmission were intravenous drug use and blood transfusion (5).

Denisenko collected data on Hepatitides among Russian seafarers from 2008 to 2010. Four out of 1630 seafarers were found to suffer from chronic hepatitis C (6).

As with hepatitis B and HIV infection, the prevalence of hepatitis C infection in seafarers is driven by the local epidemiology of the disease. The data from Georgia are conflicting and need further studies.

ILO uses the same principles for hepatitis B and C infection to assess medical fitness in seafarers: With no signs (clinical and lab studies) of hepatic impairment and confirmed low level of infectivity the seafarers’ fitness is not restricted. (7).

No vaccination against hepatitis C is available. Post exposure prophylaxis with IgG is not effective.  General control measures for hepatitis B also apply to hepatitis C.

Antiviral medicines can cure more than 95% of persons with hepatitis C infection, but access to diagnosis and treatment is low in many countries due to very high costs of antiviral medication.

 

(1) Ollero, M, Merino D, Pujol E, Marquez P, Gimeno A, Angulo C. Tattoos and hepatitis C virus infection. VIII International Conference on AIDS, Amsterdam ,19-24 July 1992. Int Conf AIDS 1992;8:180

(2) Hawkins RE, Malone JD, Cloninger LA, Rozmajzl PJ, Lewis D, Butler J, Cross E, Gray S, Hyams KC. Risk of viral hepatitis among military personnel assigned to US Navy ships. J Infect Dis 1992;165:716-719.

(3)  Hansen HL, Henrik Andersen PL, Brandt L, Brolos O. Antibodies against hepatitis viruses in merchant seamen. Scand J Infect Dis 1995;27:191-194.

(4) Akhvlediani L, Inaishvili N. The spread of HCV among the seafarers. In: 9th International Symposium on Maritime Health. Equity in maritime health and safety – development through research, cooperation and education. Book of Abstracts.Esbjerg, Denmark 3-6 June 2007.Paper 5-6.

(5) Mulic R, Muslim A, Loncar A. Prevalence of hepatitis C virus (HCV) infection in Croatian seamen.In: 9th International Symposium on Maritime Health. Equity in maritime health and safety – development through research, cooperation and education.Book of Abstracts.Esbjerg, Denmark 3-6 June 2007.Paper 5-1.

(6) Denisenko I. Hepatitides amon Russian seafarers sailing under the foreign flag. .11th International Symposium on Maritime Health. Book of Abstracts 2010: page 30. 

(7)  Guidelines on the medical examinations of seafarers / International Labour Office, Sectoral Activities Programme; International Migration Organization. – Geneva: ILO, 2013 ILO/IMO/JMS/2011/12 ISBN 978-92-2-127462-9 (print) ISBN 978-92-2-127463-6 (web pdf)

 

Sexually transmitted diseases in seafarers

As indicated above, seafarers have traditionally been seen as a special risk group for acquiring and spreading sexually transmitted diseases.

A literature search did not reveal any recent studies on sexually transmitted diseases known to be of significance in international travel including Chlamydia trachomatis, syphilis, gonorrhea, chancroid, donovanosis, Herpes genitalis.  While there is no indication of an increased risk in seafarers the disease(s) can be expected within normal rates depending on regional epidemiology.

The International Seafarers’ Welfare and Assistance Network (ISWAN) provides very useful material to educate seafarers on the prevention of sexually transmitted diseases. https://www.seafarerswelfare.org/seafarer-health-information-programme/stis-hiv-aids

Haemorrhagic fevers, e.g. Ebola Virus Disease (EVD)

On 8 August 2014, the World Health Organization (WHO) declared the Ebola virus disease outbreak in West Africa a Public Health Emergency of International Concern (PHEIC) in accordance with the International Health Regulations (2005).

Since then there have been localized outbreaks ongoing, mostly in the Central Africa. In May 2021 the 12th Ebola outbreak in Africa was declared over A vaccination is available for health-care workers via the World Health Association

Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a rare but severe, often fatal illness in humans. The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission. This occurs via direct contact, through broken skin or mucous membranes with the blood or body fluids of a person who is sick with or has died from Ebola, or through contact with objects that have been contaminated with body fluids such as blood, faeces or vomit, from such a person.

People remain infectious as long as their blood contains the virus and the incubation period is 2-21 days. A person infected with Ebola cannot spread the disease until they develop symptoms. Symptoms of EVD can be sudden and include:

  • Fever
  • Fatigue
  • Muscle pain
  • Headache
  • Sore throat
  • Vomiting
  • Diarrhoea
  • Rash
  • Symptoms of impaired kidney and liver function
  • In some cases, both internal and external bleeding (for example, oozing from the gums, or blood in the stools).

The average case fatality rate of EVD is around 50%, ranging from 25 - 90% in past outbreaks. No cases of EVD in seafarers have been reported and there is no risk for seafarers.

The IMO has published advise for ships concerning EVD

https://safety4sea.com/imo-guidance-on-ebola-virus/