Information About Tropical Skin Disease

The American Academy of Dermatology alerts travelers about seven skin diseases that commonly occur in the tropics. Parasitic infections in people who live in and visit countries and states that lie 1,621.5 miles north or south of the equator include creeping eruption, jiggers (i.e., tungiasis) and cutaneous myiasis. Fungal tropical skin infections include sporotrichosis, chromomycosis, tinea nigra and white and black piedra. Effective treatments exist for each condition except chromomycosis.

Creeping Eruption

• Hookworm infections cause creeping eruption. The worms' larvae come from feces and live in damp, warm sand or soil. People pick up hookworm infections by walking barefoot in areas where hookworm larvae live or handling the sand or soil with bare hands. The initial infection produces itchy bumps on and around the area where the larvae entered the body, and untreated creeping eruption can progress to a full-blown intestinal hookworm infection. Doctors prescribe thiabendazole (Mintezol from Merck) or albendazole (Albenza from GlaxoSmithKline) to treat creeping eruption.

Jiggers

• Known medically as tungiasis, tropical jigger infections should not be confused with chigger bites. Chiggers are Trombicula alfreddugesi larvae. Jiggers are female sand fleas (Tunga penetrans) that burrow in the skin of people's feet and lower legs with the purposes of laying their eggs. Jiggers who take root raise white lesions with black dots in their centers that can cause intense pain and itching. Options for treating jigger infections include surgical removal, suffocating the fleas by covering the black dot (i.e., the flea's air hole) with an airtight wax dressing, or applying thiabendazole, ivermectin (e.g., Stromectol from Merck) or metrifonate cream. Untreated jigger infections can lead to the development of tetanus, cellulitis and gangrene.

Cutaneous Myiasis

• Cutaneous myiasis occurs when the larvae of bot flies, green flies, black flies or flies that feed principally on the waste of cows and horses enter people's skin. The point of entry can be a wound or sore. People with cutaneous mysiasis develop red, raised bumps on their skin. As with jigger-related lesions, the bumps caused by cutaneous mysiasis have small openings in the center that serve as air holes for the parasites. Taking ivermectin tablets will kill the fly larvae, but physical removal of the larvae is also required. Usually, squeezing the bump will move the larvae close enough to the surface of the skin to allow you to pull the larvae out. Larvae that reach maturity will break free from the skin.

Sporotrichosis

• The fungus Sporothrix schenckii causes sporotrichosis. People become infected with the fungus when they handle or brush against plants on which the fungus grows, and the fungus enters people's skin through scratches or cuts. The primary symptom of sporotrichosis is a series of painless, pink-to-purple pimple-like bumps that spread and burst open after a week or two. When the bumps open, they release fungus spores that can cause lung infections, including pneumonia. Doctors prescribe itraconazole (e.g., Sporanox from Ortho McNeil Janssen) to treat sporotrichosis that remains in the skin. Amphotericin B (e.g., Fungizone from Apothecon) can treat sporotrichosis that has spread to the lungs, and patients who do not respond to itraconazole can benefit from taking potassium iodide (e.g., Iosat from Anbec).

Chromomycosis

• Fungi growing on palm trees and mimosas cause a majority of cases of chromomycosis. The most common infections involve Fonsecaea pedrosoi and Cladophialophora carrionii, and infections can take many years to produce symptoms. When people do show symptoms of chromomycosis, they develop large, discolored, draining nodules and lesions. Eliminating the infection often proves difficult, and people with chromomycosis have an increased risk for other skin infections and potentially fatal brain lesions. Medications used to treat chromomycosis include itraconazole, amphotericin B, posaconazole (Noxafil from Schering-Plough), terbinafine (e.g., Lamisil from Novartis) and flucytosine (Ancobon from Valeant).

Tinea Nigra

• Caused by an infection of the fungus Hortaea werneckii, tinea nigra is marked by the discoloration of patches of skin. Usually, the palms of your hands or the soles of your feet turn brown or black after you have handled rotting wood or walked across ground covered in decaying plant matter. Without treatment, tinea nigra spreads but continues to produce no other symptoms other than darkened skin. To clear up tinea nigra, people need to apply ointment containing prescription-strength miconazole (e.g., Vusion from Stiefel Laboratories), ketoconazole (e.g., Nizoral from Ortho McNeil Janssen) or salicylic acid.

White and Black Piedra

• You develop white or black piedra when the fungus Piedra hortae colonizes hair follicles. Depending on the strain of the fungus, the colonies raise white or black nodules at the base of individual hairs, and infections can pass from person to person on combs and hairbrushes. The nodules do not produce pain. Eliminating the infection usually requires cutting off the hair in the infected area--usually the scalp--and taking terbinafine.