Description

Next to fever and diarrheal illness, skin problems are the third most frequent medical problem in returned travelers reported to travel and tropical medicine clinics (1). Insect bites, not infrequently associated with secondary infection, are by far the most common dermatologic problem (2). Occasionally, a hypersensitivity reaction to bites may occur, leading to persistent or waxing and waning signs and symptoms or pruritic papular lesions lasting many months. Topical steroids and antihistamines may be helpful. Scabies must always be a consideration in the case of a generalized pruritic, papular rash.

NODULAR LESIONS

Recurrent pyoderma, in the form of furunculosis, may occur independently of bites as a result of colonization of the skin and nasal mucosa with Staphylococcus aureus. An intranasal anti-staphylococcal antibiotic (e.g., mupirocin)—alone or in combination with rifampin and an additional anti-staphloccocal agent—may be recommended to attempt eradication of colonization. Another painful boil-like lesion, often acquired in Africa and Latin America, is caused by an infection with the larval stage of the Tumbu (Cordylobia anthropophaga) or bot fly (Dermatobium hominis), respectively. The presence of a small, central punctum that allows the maggot to breath differentiates this condition (myiasis) from a boil. The stoma may be occluded with petrolatum jelly for one or more hours until the larva can be pulled or squeezed out (3). Another ectoparasite that produces a nodular, subcutaneous lesion on the foot is the sand flea (Tunga penetrans). Tungiasis is characterized by a painful, nodular lesion (with a central dark spot), which is actually the enlarged and egg-filled female sand flea uterus. Extracting the flea surgically is the treatment of choice.

LINEAR LESIONS

Of the linear lesions, cutaneous larva migrans, an infection with a dog or cat hookworm, is the most frequent. Infection is characterized by a very pruritic, serpiginous, linear lesion that migrates within the skin at the rate of 2-4 cm per day, most frequently on the feet. Occasionally, bullous formation, as a result of a severe inflammatory reaction, may lead to painful lesions. Treatment is with albendazole or ivermectin (4). When lime juice or another plant-derived psoralen comes in contact with the skin, an exaggerated sunburn may occur (phytophotodermatitis), giving rise to a linear, almost straight, asymptomatic lesions followed by hyperpigmentation. The pigment colour may take many weeks to resolve (5).

SKIN ULCERS

In patients who present with persistent cutaneous ulcers, the diagnosis of leishmaniasis (see the Leishmaniasis section of this chapter) must be considered. This chronic, often painful ulcer with heaped-up margins is acquired by the bite of a sand fly, most often in Latin America. It must be distinguished from pyodermas, mycobacterial, and subcutaneous fungal infections. Diagnosis is made by culture of a scraping of the base of the lesion, biopsy, and serology. The use of local or systemic therapy will be determined by knowing the likely species of the parasite and the cosmetic effect of the lesion (6).

FEVER AND RASH

Fever and rash in returned travelers is most often due to a viral infection, with dengue being the most frequent ‘exotic’ infection. Enteroviruses, such as Echovirus and cocksackie virus, hepatitis B, measles, Epstein-Barr virus, typhus, leptospirosis, HIV, and chikungunya fever are but a few of the systemic infections that must be considered. Rickettsial infections as well often present with fever and diffuse rash, or an eschar, in the case of some of the tick-borne diseases. Hemmorhagic fevers are of particular concern because of the need for rapid treatment, as in the case of meningococcal meningitis, and the public health risks associated with Lassa fever, Marburg, and Ebola viruses (7, 8).

Occurrence

Many of these conditions occur worldwide; if there is an increased risk to international travelers associated with a particular locale it is either discussed above or in the corresponding section on the organism elsewhere in this chapter. In general, vector-borne diseases are more common in tropical climates or in temperate climates during warmer months. Viruses transmitted from person to person, such as enteroviruses that may present with a rash, also circulate more commonly in warmer months in temperate climates but year round in the tropics. Community-acquired staphylococcal infections are increasing worldwide, including in developed countries. Information on outbreaks (e.g., hand, foot and mouth disease or chikungunya) may be found on official websites such as wwwn.cdc.gov/travel or http://www.who.int.en.

Prevention

Travelers are advised to include a topical antibiotic in their personal travel kit (see Chapter 2) to treat lacerations, abrasions or other skin breaks promptly, particularly in tropical climates, and to monitor the lesions until healed.

A few simple strategies can prevent the vector-borne infections described above. For example, cutaneous larva migrans is acquired by exposure of intact skin to soil or sand containing cat or dog hookworms. Therefore, travelers should consider wearing sandals or lying on a towel at beaches where animals defecate. Closed shoes are required to prevent the bites of the sand flea (tungiasis). To prevent Tumbu flies from laying their eggs on drying clothes, if the clothes cannot be dried indoors, they should be hung outdoors and not be placed on the ground to dry. Ironing clothes will also destroy the eggs. Appropriate application of insect repellent and use of other barrier methods (see Chapter 2) will also reduce the chance of being bitten by mosquitoes, ticks or sand flies. Although the mosquitos that transmit dengue and chikungunya bite primarily during the day, the sand flies that transmit leishmania are more active at dusk so barrier methods and bed nets also play an important role in the prevention of these illnesses. Travelers to tick-infested areas should look for ticks when they change clothes, after walking in areas of vegetation, and always prior to bathing and at bedtime.

Treatment

In general, most skin problems and bites will disappear with time and symptomatic treatment. An over-the-counter hydrocortisone cream can be used on bites and stings. For infections where the etiology is known, specific antimicrobial agents are recommended. Allergic rashes, whether due to medications or other hypersensitivity reactions, may be aided by an antihistamine or sometimes benefit from short-term steroid use. Dermatology consultation may be beneficial for scrapings and biopsy, if necessary. The American Society of Tropical Medicine and Hygiene website (www.astmh.org) lists clinicians who can evaluate patients with suspected parasitic infections. Subject-matter experts at CDC’s Division of Parasitic Diseases are able to assist with consultation as well (www.dpd.cdc.gov/DPDx/).

References

1. Freedman DO, Weld LH, Kozarsky PE, Fisk T, Robins R, von Sonnenburg F, et al. GeoSentinel Surveillance Network. Spectrum of disease and relation to place of exposure among ill returned travelers. N Engl J Med. 2006;354:119-30.
2. Caumes E, Carriere J, Guermonprez G, Bricaire F, Danis M, Gentilini M. Dermatoses associated with travel to tropical countries: a prospective study of the diagnosis and management of 269 patients presenting to a tropical disease unit. Clin Infect Dis. 1995;20:542-8.
3. Diaz JH. The epidemiology, diagnosis, management, and prevention of ectoparasitic diseases in travelers. J Travel Med. 2006;13:100-11.
4. Caumes E. Treatment of cutaneous larva migrans. Clin Infect Dis. 2000;30:811-4.
5. Bowers AG. Phytophotodermatitis. Am J Contact Dermatol. 1999; 10:89-93.
6. Magill AJ. Cutaneous leishmaniasis in the returning traveler. Infect Dis Clin North Am. 2005;19:241-66.
7. Lupi O, Tyring SK. Tropical dermatology: viral tropical diseases. J Am Acad Dermatol. 2003;49:979-1000.
8. Wilson ME, Chen LH. Dermatologic Infectious Diseases in International Travelers. Curr Infect Dis Rep. 2004 Feb;6:54-62.

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