Prickly heat (miliaria) is caused by excessive sweating in combination with relatively occluded sweat glands and is manifested by minor slightly itchy blisters that may break and result in scaling. They are mainly located on the trunk. It is a frequent but completely benign condition that does not require treatment.
Sunburn is another often trivial but, however, potentially dangerous condition that is frequent among seafarers. In addition to malignant consequences, ultraviolet radiation may cause phototoxic and photoallergic reactions.39 Most physicians are aware of adequate protection to UV-radiation (sunscreens, covering clothes, avoiding direct sunlight exposure and outdoor activities during midday hours, and practicing progressive exposure). It is, however, important that this advice is actually given to seafarers at risk. There is a particular threat to fair-skinned seafarers and those with a history of previous skin cancer or with compromised immunoresistance.38Excessive eccrine secretion (sweat) or hyperhidrosis may be generalized or localized – mostly to the hands, feet, axilla and face. It is triggered by thermal, emotional or gustatory stimuli and may result in bromhidrosis (malodeur) and occupational difficulties due to sweating under occlusive gloves that may cause contact dermatitis due to irritation or allergy to components of gloves (such as natural latex, rubber additives, or chromium in leather).
Dermatoses caused by marine organisms are frequently seen worldwide. Cutaneous injuries after exposure to marine environments include bacterial and fungal infections and lesions caused by aquatic plants and protists. Some disease outcomes are well described, such as Vibrio vulnificus septicaemia and erysipeloid, but others are less known, such as envenomation caused by ingestion or contact with certain dinoflagellates or cyanobacteria, which are associated with rashes that can begin within minutes after exposure.40 Although these conditions are more frequent in the tropics, they may also occur in temperate environments. In tropical countries, a high proportion of fresh water fishermen are likely to be infected by the parasite Onchocerca volvolus that in addition to “river blindness” causes skin nodules and itching.41
Many marine/aquatic invertebrates, such as sponges, cnidarians, echinoderms, crustaceans, molluscs, sea urchins, worms, and aquatic vertebrates, such as venomous fishes and stingrays are associated with different kinds of dermatologic lesions that can vary from irritant or allergic contact dermatitis to physical trauma and envenomation. These cutaneous lesions may also vary in severity from mild local reactions to severe systemic reactions.40 The presence of unusual lesions and a report of contact with an aquatic environment should alert the physician to consider a marine aetiology for a cutaneous problem.40
Lepidopterism refer to complaints, which may also relate to the skin following contacts with caterpillars, butterflies, or moths. One exotic example of such an epidemic of benign self-limited dermatitis in an oil tanker crew was related to an invasion of moths in a Caribbean port.42