SKIN PROBLEMS IN THE TRAVELER

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TRAVEL MEDICINE

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SKIN PROBLEMS IN THE TRAVELER Mary E. Wilson, MD

Skin lesions are among the most common problems that lead travelers to seek medical attention. The potentially wide range of pathogens and exposures that the traveler may have encountered requires an awareness of unusual infections found in geographically remote regions as well as familiarity with common problems. Skin lesions can be an easily observable important clue to systemic infections that require urgent intervention. Key elements of the history and examination that can help the clinician make a diagnosis include the morphology and distribution of the lesion(s), nature and geography of exposures, and time of exposures relative to the onset of the skin lesions.98 Because reaching the right diagnosis is often the greatest hurdle, this article focuses primarily on identifying the causes of skin findings. Key information is presented in tabular format to allow easy reference. Emphasis is on skin problems in persons who have visited other regions of the world rather than on skin findings in lifetime residents of tropical regions. Good references about skin problems exist to assist health practitioners who work in developing co~ntries.'~, 27, 28 Other references also review skin problems in travelers.%,61, OVERVIEW OF SKIN PROBLEMS IN TRAVELERS

Skin lesions have many causes, including all types of infections (viral, bacterial, helminthic, protozoan, fungal), infestations and bites, allergic and hypersensitivity reactions, injury by chemicals, UV light, and trauma, as well as many underlying diseases. In the returned traveler, the initial focus should always be on processes that are treatable, transmissible, or both. Because of the wide range of potential causes of skin lesions in travelers, it is helpful to know the relative frequency of each. Although there are no large,

From the Division of Infectious Diseases, Mount Auburn Hospital; Department of Medicine, Harvard Medical School; and Departments of Population and International Health and Epidemiology, Harvard School of Public Health, Cambridge, Massachusetts

INFECTIOUS DISEASE CLINICS OF NORTH AMERICA VOLUME 12 * NLTMBER 2 JUNE 1998

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general studies that provide incidence rates by type of skin lesion, some useful information has been published. Caumes and colleagues15prospectively analyzed 269 consecutive patients with travel-associated skin problems who were evaluated in their tropical disease unit in Paris over a 2-year period (1991-1993). The most common diagnoses were cutaneous larva migrans (25%),pyodermas (18Yo),arthropod-reactivedermatitis (lo%), myiasis @yo),tungiasis (6%), urticaria (5%), fever and rash (4%), and cutaneous leishmaniasis (3%). For 61% of the travelers, the skin lesions had first appeared while they were still abroad. SubSaharan Africa was the geographic origin of 38.3% of the skin problems. Common skin problems noted by other authors include sunburns, insect bites, scabies, larva currens (Strongyloides stexoralis), ecthyma due to staphylococci or streptococci, eschars of rickettsial infections, prickly heat, and onchocerciasis.61 In a study of 2567 Swiss travelers conducted by follow-up questionnaire more than one third reported a health impairment related to travel." Among the 772 who reported medical problems, 2.9% reported a skin rash. Diarrhea, fever, and respiratory tract infections were the most commonly reported problems. Visual inspection along with a history may provide an immediate diagnosis for certain characteristic skin lesions such as myiasis and cutaneous larva migrans. In many instances, laboratory studies, such as serologic tests, cultures, and biopsy, are necessary to make or confirm a diagnosis. In developing an informed differential diagnosis for skin lesions, it is helpful to characterize the lesion by general type. Historical information obtained from the patient also can help to define possible and more likely diagnoses. Tab€e1 outlines the historical data that may be useful. Because some organisms can survive for years or decades in the human host, the relevant time frame for history may be many years. The examiner should keep in mind that skin lesions that appear after exotic travel may not be due to exotic diseases. Common bacterial infections, such as staphylococcal and streptococcal infections, are more common in tropical than in temperate regions. These common bacterial infections may be superimposed on an unusual lesion, such as a leishmania1 ulcer. Although travelers tend to worry about parasites and other infections, noninfectious processes are also common-miliaria rubra, sunburns, phototoxic and photoallergic reactions, and hypersensitivity reactions to drugs taken for prophylaxis or treain1ent.2~Dermatitis may follow exposures to unfamiliar plants5 and to aquatic life (e.g., seaweed, sponges, sea urchins, other)? The tropical environment also may cause a worsening of underlying skin diseases such as acne and atopic dermatitis. The following sections review some of the more common causes and presentations. SYSTEMIC INFECTIONS ASSOCIATED WITH SKIN FINDINGS

Skin lesions may be the primary reason for the medical evaluation or may be an incidental, but nonetheless valuable, finding on a complete physical examination. Early in the evaluation it is essential to assess whether the skin lesions reflect a systemic process that requires urgent intervention. Systemic signs and symptoms may predominate. Systemic infections variably associated with a localized or diffuse rash are listed in Table 2. All are characterized by bloodstream invasion by the pathogens. Among the most common in travelers are the many rickettsial infections, examples of which exist on all continents.30, 65, 95, 96 Many clinicians associate rashes with rickettsial infections and tend to think of rickettsial infections only if a rash is present. Skin findings in rickettsial infections vary with the type of rickettsial infection and may appear only after

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Table 1. ESSENTIAL ELEMENTS OF THE HISTORY Travel and Exposures Where Duration of stay How long since return Host Age Underlying diseases Medications Immunity from past infections, immunization Pregnant? Exposures Water (swimming, wading, other) Nature of water (fresh, salt, other) Animals (history of bites, licks, scratches, other) Arthropods (or activities in close proximity to) Plants, plant products (e.g., lime) Breaks in skin (cuts, scrapes, injuries, tattoos, other) Occupational exposures Medications including over-the-counterdrugs Skin lesion@) When first appeared Morphology (ulcer, papule, macule, nodule, hemorrhagic) Location Size Evolution over time Migratory, transient vs fixed Pathology Associated signs, symptoms, laboratory data Itching, pain Fever, headache, gastrointestinal symptoms, other Physical examination Laboratory (eosinophilia, thrombocytopenia, abnormal liver function, other)

Table 2. MORE COMMON SYSTEMIC INFECTIONS IN TRAVELERS ASSOCIATED WITH SKIN LESIONS*t Bartonellosis Brucellosis Dengue Gonococcemia* HIV (primary) Leishmaniasis,visceral Leptospirosis Lyme disease Measles Meningococcemia

Parvovirus* Rat-bite fever Rickettsia1infections (many) (Rickettsia akari, R. australis, R. conorii*) Rubella Syphilis Trypanosomiasis, African Typhoid fever Varicella"

'May cause vesicular rash. Enteroviruses including Coxsackie A, echoviruses, and enterovirus 71,

as well as monkeypox also have been associated with vesicular rashes. tList is not exhaustive. Many other systemic infections can also be associated with rash.

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several days of illness or may be transient or absent altogether.48, 88 The most characteristic rashes for many of the spotted fever group rickettsioses are macular, maculopapular, and petechial. Vesicular eruptions that resemble varicella have been reported with infections due to Rickeftsia conorii, R. akari, and R. a ~ s f r u l i s . ~A~diffuse , ~ , ~ ~rash is found in only 30% to 60% of patients with scrub typhus (Orientin tsutsugumushi). An eschar (tache noire) at the site of the arthropod bite (mite, tick) is the only skin finding in some patients with rickettsia1 infections. These eschars may be revealed only on careful skin examination. Vesicular or bullous lesions do not necessarily indicate infection and can also be seen in sunburn and photodermatitis and reactions to chemicals in beetles (blister beetles), certain moths, and plants (poison ivy, lime, other). Dengue fever, increasingly common in travelers, is associated with a rash in 30% to 50% of patients. A diffuse erythema that resembles a sunburn or toxic shock syndrome may be present early in infection. A diffuse maculopapular rash and petechial lesions may appear later. Other processes that have been associated with a diffuse erythema include ehrlichiosis,4°drug reactions, Kawasaki syndrome, scarlet fever, and staphylococcal and streptococcal toxic shock syndromes. Patients with relapsing fever (caused by Borreliu species) may have a rash that is maculopapular, papular, petechial, or purpuric and may be focal or generalized. In the review by Southern and Sanford,gorash was more common in tick-borne than in louse-borne (28% vs 8%) relapsing fevers. Common infections such as measles and rubella that are controlled by immunization programs in most of the world are still sometimes carried home by travelers, often confusing their health care providers who may be expecting exotic tropical viruses.21 Many of the viruses that cause hemorrhagic fevers can produce a rash, but these skin findings are often of little help in distinguishing one infection from another, and other clinical findings usually take front and center stage. The possibility of bacterial infections such as leptospir~sis~~, 71 and meningococcemia that can cause hemorrhagic findings should always be kept in mind because of the importance of prompt antimicrobial therapy in these infections (Table 3). Leptospirosis also can be associated with a erythema nodosum-like rash.Z6Overall, rashes were reported in 9% of 483 cases of leptospirosis in the United s t a t e ~ . ~ ~ Supportive care can be lifesaving in dengue shock syndrome and other viral hemorrhagic fevers, although specific therapy for most is currently unavailable. Lassa fever is an important exception, as ribavirin is clearly effective if started early. A petechial or hemorrhagic rash has been described in patients with disseminated strongyloidiasis. This would not be expected in a short-term visitor to a Table 3. MORE COMMON CAUSES OF PETECHIAL OR HEMORRHAGIC SKIN

LESIONS IN TRAVELERS* Dengue fever Leptospirosis Meningococcemia Rat-bite fever Rickettsia1 infections Strongyloidiasis (disseminated) Viral hemorrhagic fevers (multiple, including Argentine, Bolivian, Crimean-Congo,Ebola, Lassa, Venezuelan, others) 'Scurvy and other noninfectious processes can be associated with hemorrhagic rash.

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tropical region. Because strongyloidiasis can persist, potentially for the lifetime of the host through an autoinfective cycle, infection may progress or become manifest long after a person has left an endemic region. Disseminated disease is seen primarily in persons who are immunocompromised by treatment or because of underlying disease.zo Systemic infections associated with skin lesions include bacterial, viral, fungal, helminthic, and protozoan pathogens and multiple routes of transmission. Although typhoid fever is one of the more common infections reported in travelers, skin lesions are often absent or transient and unimpressive and thus provide limited assistance in the diagnosis. Papulonodular or erythema nodosum-like lesions were reported in 6% of 436 patients with brucellosis from Spain? A nonspecific rash is seen in 10% to 20% of patients with tularemia; patients may also have lesions of erythema nodosum.36African trypanosomiasis, rarely imported by travelers, can be associated with a chancre at the site of the tsetse fly bite and a later rash, characterized by erythematous, circinate patches that may wax and wane and are most prominent on the trunk.22Bartonellosis, due to Bartonella bacilliformis (also known as Carrion disease, Oroya fever, and verruga peruana), is a bacillemic infection with diffuse skin lesions that may range from papules to nodules to fungating, ulcerated masses. Skin lesions may persist for months. The infection, which is transmitted by the bite of an infective sandfly, is found primarily on the western slopes of the Andes in South America." New sexual contacts are common during travel. Sexually transmitted systemic infections such as HIV and hepatitis B must be considered as well as sexually transmitted diseases with pathology limited to genital organs (see also section on ulcers). DIFFUSE SKIN LESIONS SECONDARY TO PENETRATION BY PATHOGENS

Diffuse skin lesions can follow skin penetration by pathogens such as those found in water or soil. Oceans, streams and lakes, and artificially created containers, such as hot tubs, can provide the vehicle through which pathogens can reach human skin." Cercarial dermatitis, also known as swimmer's itch, is an itchy maculopapular eruption that follows penetration of skin by cercariae of schistosomes. Lesions are restricted to parts of the body exposed to water and may be less prominent in areas covered by a bathing suit or other protective clothing6,l9 An itchy or tingling sensation may be noted shortly after exposure to the infested water, followed in hours to a day or more by the development of itchy red papules that may become vesicular. Secondary bacterial infection may result from the skin abrasions due to intense itching and scratching. Schistosome dermatitis has been reported from every continent (except Antarctica) and is associated with fresh water and occasionally salt or brackish water exposure. Nonhuman schistosomes (often avian schistosomes) contaminating these waters are unable to mature in the human host, but elicit intense inflammatory response that typically becomes more severe with repeat exposures. A similar but less severe rash with redness, urticaria, and itchy papules can follow penetration of the skin with human schistosomes. Among 28 travelers who developed schistosomiasis after exposures in Mali, West Africa, 10 (36%) had schistosomal dermatiti~?~ Schistosomiasis caused by human schistosomes also can be associated with other skin lesions long after penetration of the cercariae. These include urticaria,

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edema, and symptoms suggesting hypersensitivity to parasite antigens, and papular or nodular skin lesions related to deposition of eggs in the dermis. The tissue shows a granulomatous reaction.', 33 Ectopic egg deposition in Sckistosoma haematobium usually affects the genital area, although it has been reported on other areas of the body? Seabather's eruption, caused by penetration of skin by Linucke unguiculata, Edwardsiella lineata, and probably other larvae of the phylum Cnidaria, is characterized by an intensely itchy, papular rash that occurs after swimming in the The distribution of lesions matches areas covered by a bathing suit or points of pressure (e.g., wristbands of diving suits, flexural areas). The tiny jellyfish larvae become entrapped by the bathing suit, which acts as a mechanical stimulus for the release of nematocysts and injection of toxin by the larvae. Outbreaks are sporadic and are probably influenced by Gulf Stream currents and other environmental factors.99Patients with extensive involvement may have systemic symptoms, including fever. Skin lesions are inflammatory papules, often becoming vesicular or pustular. Many reports have come from the Atlantic coast of North America, especially south Florida, and from the Caribbean. Table 4 lists processes associated with itching. Hot tub folliculitis, also known as whirlpool dermatitis, has followed exposures in hot tubs, whirlpools, swimming pools, and water slides. The itchy, maculopapular and vesiculopustular eruption develops within 48 hours of exposure and is most prominent in areas covered by bathing garments. Pseudomonas aeruginosa is the cause. Unless persons are immunosuppressed, the process is usually self-limited.6

Table 4. PRURITIC SKIN LESIONS IN TRAVELERS Helminthic infections (itching may be transient or intermittent) Cercarial dermatitis (schistosome dermatitis) Cutaneous larva migrans Dracunculiasis Gnathostomiasis Hookworm Loiasis Mansonelliasis due to Mansonella ozzardi, M. perstans, and M. strepfocerca Onchocerciasis Pinworms (enterobiasis; usually no associated rash) Strongyloidiasis (larva currens) Arthropod bites and infestations Botfly larvae (form of myiasis) Chiggers Fleas Lice (crab and body) Mosquitoes Scabies Other Drug hypersensitivity reactions Phytodermatitis Seabather's eruption Many viral infections (varicella, rubella, others)

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Table 5. MIGRATORY SKIN LESIONS"

Infection

Comments

Cutaneous larva migrans Dracunculiasis Fascioliasist Gnathostomiasist

Creeping eruption Movement of worm just before eruption Migratory areas of inflammation Migratory inflammatory subcutaneous swellings; creeping eruption; Urticaria Itchy tracts at points of penetration Migratory inflammatory swelling; painful or itchy Migratory swelling or subcutaneous nodules Edematous, painful migratory swellings Itchy, papular, and migratory serpiginous lesions (larva currens) Visible movement of maggot@)within lesion; larvae of some Diptera migrate in soft tissue

Hookworm Loiasist Paragonimiasis Sparganosis Strongyloidiasis Myiasis

'All of these can be associated with eosinophilia. tEosinophilia may be high grade.

MIGRATORY SKIN AND SOFT TISSUE LESIONS

A characteristic of skin lesions that can be disconcerting to the patient and of discriminatory value to the clinician is the migratory nature of skin lesions. Intermittent and migratory lesions of the skin and subcutaneous tissues can reflect migration of parasites in human tissues?, 24, 53* 87 Pathogens associated with migratory lesions are listed in Table 5. Often the geographic and exposure history is essential in trying to assess which processes are more likely in order to focus the diagnostic work-up. Migrating parasites are among those causing urticaria and eosinophilia (Table 6).

Cutaneous Larva Migrans Cutaneous larva migrans, also known as creeping eruption, results when infective larvae of animal hookworms (usually Ancylostomu bruziliense but occasionally others) penetrate the skin and migrate in the superficial tissues, producing a characteristic serpiginous erupti0n.5~In the absence of intervention, the larvae can migrate for weeks but rarely for as long as a year, often causing distress to their human host.81Infection is acquired when human skin comes into direct contact with soil, sand, or other material contaminated with feces Table 6. HELMINTHS ASSOCIATED WITH URTICARIA AND ESOINOPHILIA' Ascariasis Fascioliasis Gnathostomiasis Hookworm Loiasis Onchocerciasis

Paragonimiasis Schistosomiasis Strongyloidiasis Trichinosis Visceral larva migrans

'Urticaria may be noted only at limited times in the life cycle of the helminthic infection. Some viral infections, such as hepatitis B and enteroviruses, also have been associated wiih urticaria.

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from animals (usually dog or cat) infected with hookworms. Lesions are itchy and occasionally painfulJ4 Appearance is usually erythematous and linear or serpiginous. Lesions can be papular or vesiculobullous. They begin within several days of exposure to third stage larvae and develop most often on the feet, buttocks, and thighs. Larvae are located beyond the visible leading edge of the skin track. Although the process is typically self-limited, systemic antiparasitic therapy is effective.18,85 In a small randomized trial of ivermectin versus albendazole, a single 12-mg dose of ivermectin was more effective than single dose albendazole.I6A 3-day course of albendazole, 400 mg/day, is, however, probably more effective than single dose ivermectin, and it is currently the treatment of choice. Topical treatment is no longer recommended. Other skin penetrating nematode larvae can produce similar findings. Larvae of the human hookworm (Necator arnericanus) can cause a transient creeping eruption at the time of skin penetration. Chronic strongyloidiasis is associated with episodic, itchy, urticaria1 or serpiginous skin lesions (larva currens), most often on the buttock, groin, or trunk.5* 91 They last a few hours to a day and movement may reach 5 to 10 cm per hour. Skin changes were reported in 84% to 92% of ex-POWs infected with strongyloides. Larva currens was noted in another group of patients with chronic strongyloidiasis.2 Ivermectin has been reported to be effective in treating larva c ~ r r e n s . ' ~ Gnathostomiasis

Skin lesions associated with gnathostomiasis can begin as early as 3 to 4 weeks after ingestion of the parasite, although they can be delayed until months or even years laterJ3,&1 The third stage larvae cause localized swellings that typically last 1 to 2 weeks and are associated with edema, pain, itching, and variable erythema. Because a single gnathostome can cause symptoms, cases have occurred after a brief stay in an endemic area, usually Southeast Asia, or after eating foods from those areas. In addition to causing lesions in the skin and soft tissues, the worm also can migrate to tissues throughout the body causing eye, gastrointestinal, genitourinary, central nervous system, pulmonary and other localized disease.84 Loiasis

Loiasis, a filarial parasite causing migratory lesions and eosinophilia (often high grade) follows the bite of an infective Chysops, a fly.* Symptoms typically appear at least 4 months after exposure and can first appear more than 5 years after exposures in an endemic region. Classic findings are localized areas of angioedema, the so-called Calabar or fugitive swellings. These warm, itchy, or painful inflammatory swellings usually disappear within a few days and may recur multiple times per year. Fever may accompany migration of worms, which can survive more than 10 years. Worms migrating at a rate up to 1 cm per minute may be visible crossing the conjunctivae or bridge of the nose. NODULES AND PAPULES

Nodular skin lesions typically occur at the site of inoculation or following bloodstream or lymphatic dissemination of organisms (Table 7). Some parasites

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Table 7. NODULES AND SUBCUTANEOUS SWELLING* Infection Coenurosis Cysticercosis Dirofilariasis Dracunculiasis Echinococcosis Fascioliasis Filariasis Loiasis Onchocerciasis Wuchereria bancrofti Gnathostomiasis Paragonimiasis Sparganosis Visceral larva migrans

Comments Subcutaneous nodules, usually single Painless, rubbery cysts; often multide Subcutaneous nodule Papule becomes vesicular at site of discharge of larvae Soft, subcutaneous cysts, varying sizes Rarely painful or itchy subcutaneous nodules Painful or itchy swellings Subcutaneous nodules, itching, papules Recurrent lymphangitis, scrota1 mass Edematous. recurrent,. miaratotv - subcutaneous swellinas Subcutaneous nodules Edematous, painful migratory swellings Nodules (post-kala-azar)

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Other causes Bartonella Leptospirosis Lyme disease Mycobacteria Fungi, multiple Tungiasis

Multiple lesions, may be verrucous Pretibial red nodules Erythema migrans, rare nodules; fasciitis, rnyositis Mycobacferium marinum, M. uicerans, M. leprae, other All invasive fungal infections can cause nodular skin lesions

*List is not exhaustive.

can breach tissue barriers, gaining access to many body sites. Nodular or cystic masses in the skin are found in several parasitic infections, including echinococcosis,S dirofilariasis7s*89 cysticercosis,'w coenurus,92and toxocariasis.82A widespread papular eruption has been described secondary to Ancylostoma c~ninum.~O Most invasive fungal infections can cause skin lesions, including nodules. Biopsy of an easily accessible nodular skin lesion can sometimes be a useful and rapid way to make a diagnosis?' Onchocerciasis, a common cause of skin nodules in endemic areas, typically causes an itchy rash in visitors to those areas.-, 79 Because this parasitic infection usually has an incubation period of 1 to 2 years, patients may not think to mention travel and exposures that may be relevant. Onchocerciasis occurs primarily in persons who spend at least 1 month or longer in endemic regions. Diagnosis is usually made by identification of microfilariae on a skin snip.

Lymphangitis Lymphangitis with retrograde progression, lymphadenitis, orchitis, and epididymitis are characteristic of bancroftian filariasis-an infection uncommon in the usual tra~eler.9~ Similar clinical features are caused by Brugia malayi and B. t i m ~ r i .74,~ 83 ~, Nodular lymphangitis has been reported with a number of infections: leishmaniasis, sporotrichosis, nocardia, tularemia, and with Mycobacterium m ~ r i n u m . ~ ~ These infections are typically acquired after inoculation of the agent into the skin by a biting arthropod or through minor traumatic injury. In contrast to

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streptococcal lymphangitis, these inflammatory processes may have a slower clinical course. Bites, fcfoparasifes and Infestations

Bites of arthropods carry several risks. These include transmission of a long list of pathogens; allergic, localized, and systemic hypersensitivity reactions to material injected; granulomatous reaction to retained parts; and injury to skin and tissues through which other pathogens can enter and infect. In developing regions, Clostridiurn fefani infection of a wound in an unimmunized person can lead to tetanus. A few arthropods make their home in (myiasis, scabies) or on (lice) human skin. The excoriations of skin from scratching also predispose to secondary infection. Among the more common is scabies, an infestation with a Some ticks worldwide distribution that is sometimes acquired during transfer a potent neurotoxin that causes paralysis. Common skin manifestations of ectoparasites and biting arthropods are listed in Table 8. Many arthropods Table 8. ARTHROPOD BITES AND INFESTATIONS Comments

Arthropod

Bedbug Black fly (Sirnulimy Chigger ( Trornbicula irritans, others)' Deer fly (Chrysops)' Flea (Pulex irritansy Mosquito* Myiasis Pediculosis due to Pediculus humanus corporis (body lice)* Pediculosis due to Pediculus humanus capitis (head lice) Phthiriasis due to Phthirus pubis (pubic lice) Midge (Culicoides)* Sandfly (Phlebotornus)' Scabies (Scarcoptes scabiei) Tick' Hard ticks Soft ticks Triatomine bugs (kissing bugs, Reduviidae)" Tsetse fly (Glossina)* Tungiasis (chigoe fleas, Tunga penefrans)

Elythematous papules, often in clusters or linear distribution. Petechial or hemorrhagic; may last for weeks; severe focal edema in sensitized persons Painful or itchy; may vesiculate Itchy, maculopapular lesion Painful papule, central punctum Early urticaria and erythema; pruritic papules, often in clusters Itchy papule, wheal Infestations of human tissue by fly larvae. Variable manifestations depending on infesting fly Itchy wheals; erythematous maculopapular rash; may be hemorrhagic Severe itching, red papule, white nits Itching; lice attach to pubic hair, eyelashes Itchy wheal and papule Itchy or painful wheal, papule Itchy papules, vesicles. Linear burrows. Uncommon urticaria, nodules Regional edema; chronic nodule (tick granuloma) Macules, papules, central necrosis Transient urticaria; vesicles or pruritic papules Painful red, indurated lesion Burrow into host tissue, often feet. Itchy white papules or vesicles with central black depression; may ulcerate

'Transmit organisms that are pathogenic for humans.

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with the potential to transmit pathogens can cause itchy, painful, or unpleasant lesions, even if no pathogens are transmitted.'0 Myiasis

Myiasis refers to the infestation of human tissues with one or more larvae of flies of the order Diptera." 32,75 The larvae may be obligate tissue parasites or may infest necrotic material opportunistically. The most common form observed in returning travelers is furuncular myiasis, which is caused by Derrnatobia hominis, human botfly, or Cordylobia anthropophaga, the tumbu fly. The female 0. horninis lays her eggs on a mosquito where they adhere to the legs and ventral abdominal surface. When the mosquito transporting the eggs feeds on a warmblooded host, the larvae emerge from the eggs and penetrate the skin or enter through the puncture wound made by the mosquito. The larvae develop in the subdermal tissue over a period of weeks. Typically, only one larva develops in each lesion. The tumbu fly typically lays her eggs in soil. Flies and clothing in contact with soil may become contaminated with eggs. Larvae from these eggs in clothing penetrate the skin. Lesions from the tumbu fly are often multiple and may involve areas of the body awered by clothing. In both instances the initial lesion can suggest an insect bite that slowly enlarges into a nodule that may reach 1to 3 cm in diameter. On close inspection a small central opening is seen, and occasionally the respiratory spicules of the larva may be visible. Scant serosanguineous fluid may drain from the lesion. Patients often report a sensation of irritation, crawling, or pain. Removal of the intact larva is curative, although secondary bacterial infection can complicate the infestation. A range of approaches have been successful and have often included occluding the opening (eg., with petroleum jelly or strips of bacon) and gentle extraction of the intact larva when it protrudes its abdomen to reach air? Some larvae can move from the site of entry to another area of the body, causing migratory swellings that are red and painful. Other forms of myiasis can cause extensive tissue necrosis in existing wounds or in normal tissues (e.g., destruction of eye, invasion of ear, nasopharynx, central nervous system). The latter are not particular problems for the usual traveler. Tungiasis

When the female sand flea (Tunga penetrans) penetrates the skin and burrows into tissue, usually on feet and often under toenails or between toes, she feeds on blood, enlarges to a spherical form 5 to 8 mm in diameter, and produces eggs that are expelled through the host's skin. Symptoms of itching and pain become prominent 8 to 12 days after penetration, although the flea may live up to 1 month. Lesions are nodular, may be single or multiple, and sometimes ulcerate. Complications include secondary bacterial infections. Treatment is removal of the ULCERS Leishmaniasis

Leishmaniasis is a protozoan infection transmitted by the bite of an infective female sandfly. The three major clinical syndromes, cutaneous, mucocutaneous,

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and visceral, reflect the tissue location of infected macrophages. Infection is typically subacute to chronic. Among the most important skin lesions to recognize because of the potential for late complications is cutaneous leishmaniasi~.~~, 4 5 * 4 7 , 6 8 Because lesions often appear after return from tropical travel, may be asymptomatic and indolent in progression, and are not associated with systemic systems, they are often ignored or first evaluated after a long delay. Visceral leishmaniasis is sometimes associated with a diffuse rash (post-kala-azar), seen primarily on the Indian subcontinent, occurring one to several years after apparent cure. It is characterized by nodular infiltration of the skin. Overwhelmingly the most common skin lesions seen in travelers are those of cutaneous leishmaniasis, caused by several leishmania, found focally in the Americas, Asia, and Africa. Leishmaniasis in the Americas is caused by at least eight different Leishmania species. About 60,000 clinical cases are estimated to occur each year. Between 1985 and 1990, the Centers for Disease Control and Prevention (CDC) was notified of 129 cases of cutaneous leishmaniasis because of requests for sodium stibogluconate for treatment. More than half of the patients had acquired infection in the Americas, reflecting the travel patterns of US citizens. The risk estimates varied greatly by country, ranging from about 1 in 1000 travelers to Suriname, to fewer than 1 per 1 million travelers to Mexico. Among the 58 persons interviewed in detail, the median time spent abroad was 54 days, with a range of 4 days to 3 years. The subset of 19 tourist-visitors spent a median of 20 days out of the United States. Forty-one percent first noted their skin lesions while out of the country, whereas 17"/0 did not notice skin lesions until they had been back for more than 1 month.49The mean number of skin lesions per person was 1.4, with a range of 1to 8. The body site of the lesion@)was most often the lower legs, followed by the head and arms. Cutaneous leishmaniasis typically begins as a papule that enlarges to a nodule with a central crust that drops off to expose an ulcer that is painless, chronic, and many have a raised border and satellite lesions. Regional lymphadenopathy may be present. Because some New World leishmania that cause cutaneous ulcers can be complicated by late mucocutaneous disease, it is important to identify the infecting species and give adequate treatment to patients at risk for late complications. Cutaneous leishmaniasis can be diagnosed by finding amastigotes in tissue or on smears, although sensitivity is low (14Y0-18Y0). Biopsy specimens also can be cultured for Leishmania using special media. The most commonly used treatment is stibogluconate sodium, available through the CDC Drug Service. Other Causes of Ulcers

Coynebucterium diphtheriae can infect the skin causing ulcers that typically have a punched out appearance with an adherent eschar. C. diphtheriae also can be found in skin lesions that resemble ecthyma, impetigo, pyodermas, and other common skin problems. Co-infection with staphylococci or streptococci may be noted.7Other causes of skin ulcers in travelers are listed in Table 9. Infections with Mycobucterium ulceruns (Buruli ulcer) begin as a nodule that ulcerates and enlarges over a period of several months. Lesions usually are on the extremities (9oY0)and usually single? The ulcer has extensively undermined edges and a necrotic base and rarely extends into muscle or bone. Systemic symptoms are typically absent. Available antimycobacterial drugs have limited benefit. Wide surgical excision can be curative. Infection is endemic in focal

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Table 9. CAUSES OF SKIN ULCERS IN TRAVELERS Bacteria

Comments

Anthrax Chancroid Diphtheria Granuloma inguinale Leprosy Lymphogranuloma venereum Melioidosis Mycetoma Mycobacterium marinum M. ulcerans Plague Pyoderma

Syphilis Tropical ulcer Tuberculosis Tularemia Yaws

Hemorrhagic, surrounding edema Painful genital; single or multiple Shallow ulcer Painless genital ulcer Neuropathic ulcer Late ulceration Necrotic ulcer with local cellulitis Ulcers, sinus tracts Nodules may ulcerate Deep ulcer (Buruli ulcer) Breakdown of bubo Crusted ulcer associated with staphylococci and streptococci Eschar at inoculation site for some spotted and typhus fevers Painless ulcer with indurated edge Painful, necrotic ulcer Nodule ulcerates at primary inoculation site Ulcerated nodule Papule ulcerates

Protozoa Amebiasis Leishmaniasis

Rapidly growing, painful, necrotic ulcers Painless, rolled edge; chronic

Rickettsia1infections

Other Brown recluse spider bite

Painful, edema, erythema; necrotic eschar

areas of Africa; Southeast Asia; Papua New Guinea; Australia; and Central and South America. Skin involvement is seen in a small minority of patients with amebiasis. Lesions are often serpiginous ulcers with heaped up or even verrucous borders. The base is purulent. Lesions are often painful and progress rapidly. The most common locations are the perianal and genital areas.", 69 The sexually transmitted infections, chancroid, syphilis, granuloma inguinale, and lymphogranuloma venereum, are important causes of ulcerations or skin erosions in the genital area. DIFFERENCES BETWEEN VISITORS AND LONG-TERM RESIDENTS

The presence and intensity of symptoms and the magnitude of eosinophilia can vary depending on the age at first exposure, the immunologic state of the host, and the number and timing of subsequent exposures to a number of pathogens. Visitors and long-term residents of endemic regions have different patterns of response to a number of helminths. With loiasis, recent arrivals (visitors) to endemic regions are more likely to have Calabar swellings (95%vs 16%for residents) and less likely to have detectable microfilaremia (10% vs goo/,) than the native 73 Nonimmune persons who become infected with

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filariae, such as Brugia timori, after moving to endemic regions rarely have detectable microfilaremia and develop elephantiasis faster and at a higher rate than do local residents who have been exposed to the parasite since childhood.n Onchocerciasis in visitors to endemic regions most often causes dermatitis without nodules and eye disease; microfilariae were absent or present in low density in the skin. This contrasts with persons living in endemic regions who commonly have eye disease and nodules in addition to pruritus.67

CONSEQUENCES OF TREATMENT

Drug therapy for several helminthic pathogens can lead to a transient worsening of symptoms and a rise in eosinophils. Patients with loiasis may experience pruritus, dermatitis, arthralgias, and m y a l g i a ~Patients .~~ with schistosomiasis may develop respiratory symptoms and new pulmonary infiltrates in association with treatment. The initial course of ivermectin treatment of patients with onchocerciasis was associated with edema of the face or extremities, myalgias, and itching and a papular rash,” although controlled trials do document the efficacy of treatment.I3 In patients with cutaneous larva migrans a bullous reaction has been observed at the site of the skin lesions about 3 days after treatment with albendazole and ivermectin.16 Ivermectin treatment of the skindwelling filaria, MansoneZZa streptocercu, caused pruritus and an acute papular dermatitis in 45% of 86 patients in western Uganda.39These changes are thought to reflect the host immune response to antigens released or exposed from dead or dying larvae or worms.

DIAGNOSIS

Diagnosis is sometimes made by the gross appearance of the parasite (e.g., lice, fly larvae) but more often involves examination of material by microscopy (e.g., blood smears for microfilariae or other parasites, skin snips for microfilariae, skin or other tissue biopsy, dark field examination, stool examination for ova and parasites, or other special stains of fluids or aspirates) is necessary to make a specific diagnosis. Cultures of blood, and of other material for bacteria, fungi, and viruses may yield a diagnosis. Serologic studies that detect antibodies or antigens are valuable in the diagnosis of many infections. Increasingly, use of polymerase chain reaction (PCR) and other molecular techniques will be available to aid the clinician.

SUMMARY

Skin lesions are common in travelers and include a mix of mundane dermatologic problems and rare diseases acquired only in remote or tropical regions. The morphology, distribution, and progression of the lesions are useful in assessing possible causes. Early in the evaluation it is important to determine whether the patient might have a process that is rapidly progressive, treatable, or transmissible. In addition to routine laboratory studies, biopsy and serologic tests are often necessary to confirm a specific diagnosis.

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