The skin is colonized by a variety of saprophytic microorganisms, some of which, however, may become invasive in case of skin lesions or with reduced immune resistance. Other microorganisms may infect the skin even with normal host resistance.
There are several studies suggesting that infectious conditions may well account for the majority of skin diseases among seafarers. For example Lucas et al. recorded 68% of radio medical calls due to dermatologic conditions to be infectious1 and a study among fishermen in Irak attending an outpatient clinic reached a similar proportion (60%).27 Dahl has recently reviewed the prevention and treatments on wound infections on board and discussed the involved pathogens.2
Microfungal infections - dermatophytoses
The most important fungi that cause skin disorders at various locations (Tinea) include Trichophyton, Microsporium and Epidermophyton.
Tinea capitis afflicts the scalp, in particular in minors (Figure 18). Tinea corporis or ring worm may be caused by any dermatophyte that is transmitted from a human or an animal and starts with small pustules that eventually enlarge outwards and produce itchy patches with a more light coloured central area (Figure 19). Tinea cruris is very common and causes an itching, red rash in the groins and perineum, in particular in men (Figure 20).
Figure 18. Tinea capitis.
Figure 19. Tinea corporis.
Figure 20. Tinea cruris.
Tinea pedis – athlete’s foot – is caused by several species of fungi, most importantly Trichophyton. This common mycosis presents with an itchy red rash and scaling. Hyperkeratosis and fissure formation are frequent in chronic cases. It is mainly seen in the spaces between the lateral toes. Accompanying bullous id-reactions on the sole are common. In adults it is mostly accompanied by onychomycosis with discoloured, distorted and friable nails. Being found in two thirds of seafarers compared to one forth of a rural comparison population, this is a common problem in seafarers. T. interdigitale dominated by 3-4:1 relative to T. rubrum. Each year of sailing increased the frequency of tinea pedis.28
Tinea manuum is less frequent and mostly occurs in conjunction with tinea pedis. A unilateral palmar affliction should raise suspicion of a fungal infection but may be misinterpreted as dermatitis in the absence of confirmative analyses for microfungi.
Figure 21. Tinea pedis.
Figure 22. Onychomycosis.
Topical antifungals are increasingly effective for treatment of skin infections but onychomycosis may need long-term oral therapy.
Staphylococci and Streptococci are the bacteria most often involved in skin infections. When a number of follicles are infected separately, a folliculitis ensues (Figure 23). When many closely situated follicles are infected concomitantly, a limited abscess – a furuncle – may develop (Figure 24). When many follicles are infected, a larger abscess may develop and form a carbuncle.
The highly contagious impetigo (Staphylococci or Streptococci) is a superficial skin infection resulting in patches of inflammation with honey coloured crusts and is mostly seen in children.
Figure 23. Folliculitis.
Figure 24. Furuncle
The maritime environment may easily contaminate cuts and wounds and cause cutaneous infections.1,2 Lacerations – in particularly of the hands – are frequent in particular among fishermen.29 Without diagnostic facilities and a limited range of antibiotics onboard, the prevention of these accidents is regarded a high priority.2,29 Early treatment of wounds may reduce the likeliness of infections.
Telemedical advice should be sought early in case of wounds that may be infected. During radio medical contacts digital photographs are likely to be of major assistance for giving advice about treatment at sea. Fresh clean cuts may be sutured or closed by adhesive tape. If infection arises, the wound should be drained and one or more sutures removed. Most wounds, however, should be regarded as contaminated and should be left open. Antibiotics should be administered immediately with hand or puncture wounds.2
While folliculitis can be treated with topical or systemic antibiotics, an abscess should be incised and drained. Antibiotics should be administered if there is spread of the infection to the surrounding tissue (cellulitis), lack of response to drainage, or if the abscess is located in an area, which is difficult to drain (face, palm, genitalia). Cellulitis requires 5-10 days of broad-spectrum antibiotics such as dicloxacillin, cephalexin, clindamycin, or erythromycin.2 This is an important and frequent condition at sea that accounts for the majority (68%) of radio medical calls for dermatological conditions.1
The lack of response in 2-3 days suggests an infection with methicillin-resistant S. aureus infection.2 A Dutch telemedical study has indicated an increasing incidence of skin infections between 2002 and 2006 (5.5% - 8.8%). In the same observation period cases with features consistent with methicillin-resistant S. aureus infections doubled from 36% to 74%.30 The challenges related to methicillin resistance vary considerable worldwide with certain countries experiencing only few problems, while resistance is a major public health issue in others. This difference is related to the various practices related to the use of antibiotics. In this context it should be realized that a seafarer, who has been admitted to hospital abroad, might well import resistant strains of bacteria to his home country.
A strong red rash with well demarcated edges particularly in the face (Figure 25) or on the legs (Figure 26) accompanied by high fever, shivering and malaise signals an infection – erysipelas – with bacteraemia (streptococci). Erysipelas is a medical emergency that requires immediate penicillin treatment.
Figure 25. Facial erysipelas.
Figure 26. Erysipelas of the lower limb.
Mycobacterium marinum infection may be acquired worldwide from contact with contaminated salty and fresh water in combination with skin trauma such as injuries from fish bites or fins or with existing scratches of the skin. A particularl risk has been reported for fishermen.31 The infection may extend from the skin to deeper layers such as tendons and become debilitating if misinterpreted (Figure 27).
Figure 27. Mycobacterium marinum of the hand.
A host of viruses can cause skin symptoms. In this context, the two most common viral skin infections are is described.
Herpes simplex infection is a contagious skin condition. The primary infection frequently causes blisters in the face (Figure 28) and mouth (Figure 29). The virus hides in a nervous ganglion and may under certain circumstances (other diseases or weakened general condition) travel along nerves and cause recurring blisters.
Figure 28. Herpes simplex.
Figure 29. Herpes simplex
Varicella zoster virus causes two diseases: Varicella – chicken pox – is mostly a disease of children, but in many – especially tropical – countries where seafarers are recruited varicella also occurs in late adolescents and adults32,33 (Figure 17). Consequently it may well spread among seafarers, in particular those from tropical countries, and cause small epidemics on board,. It latently resides in nerve ganglions adjacent to the spinal cord and may under special circumstances (other diseases and general weakening) travel along the cutaneous nerves and cause painful blisters in the innervated skin territory – herpes zoster. Herpes zoster therefore often appears in a unilateral belt on the trunk (Figure 30). The pain may persist after disappearance of the blisters. Involvement of the eye region demands special attention to avoid corneal damage.
Figure 30. Herpes zoster.
Herpes simplex and herpes zoster may be treated with topic anti-viral agents. In complicated cases systemic treatment may become necessary. Ointment with anaesthetics may prove helpful in herpes zoster.