Chapter 5Post-Travel Evaluation

Jay S. Keystone

DESCRIPTION

Skin problems are one of the most frequent medical problems in returned travelers. The largest case series of dermatologic problems in returned travelers from the GeoSentinel surveillance network showed that cutaneous larva migrans, insect bites, and bacterial infections were the most frequent skin problems in returned travelers, making up 30% of the 4,742 diagnoses (Table 5-06). In another review of 165 travelers who returned to France with skin problems, cellulitis, scabies, and pyoderma led the list of skin conditions. These data are biased in that they do not include skin problems that were diagnosed and, in many cases, easily managed during travel or that were self-limited.

Skin problems generally fall into one of the following categories: 1) those associated with fever, usually a rash or secondary bacterial infection (cellulitis, lymphangitis, bacteremia, toxin-mediated) and 2) those not associated with fever. Most skin problems are minor and are not accompanied by fever. Diagnosis of skin problems in returned travelers is based on the following:

• Pattern recognition of the lesions: papular, macular, nodular, linear, or ulcerated
• Location of the lesions: exposed versus unexposed skin surfaces
• Exposure history: freshwater, ocean, insects, animals, or human contact
• Associated symptoms: fever, pain, pruritus

Remember that skin conditions in returned travelers may not have a travel-related cause.

PAPULAR LESIONS

Insect bites, the most common cause of papular lesions, are frequently associated with secondary infection or hypersensitivity reactions. Bed bugs, fleas, and reduviid (triatomine) bugs can all produce papules in groups of 3 (“breakfast, lunch, and dinner”). (For more information about bed bugs, see Box 2-03.) Scabies is a mite that frequently presents with a generalized pruritic, papular rash. Scabies burrows may present as papules or pustules in a short linear pattern on the skin.

Onchocerciasis, also known as river blindness, is caused by the filarial nematode Onchocerca volvulus. Generalized pruritus is the rule, often associated with a papular rash. The filariae are transmitted by the bites of day-biting black flies. The main risk occurs in long-stay travelers living in rural sub-Saharan Africa and, rarely, Latin America.

NODULAR OR SUBCUTANEOUS LESIONS, INCLUDING BACTERIAL SKIN INFECTIONS

Bacterial skin infections may occur more frequently after bites and other wounds in the tropics, particularly when good hygiene cannot be maintained. Organisms responsible are commonly Staphylococcus aureus or Streptococcus pyogenes. The presentations can include abscess formation, cellulitis, lymphangitis, or ulceration. Furunculosis, or recurrent pyoderma, is the result of colonization of the skin and nasal mucosa with S. aureus. Boils may continue to occur weeks or months after a traveler returns.

In addition to pyodermas, cellulitis or erysipelas may complicate excoriated insect bites or any trauma to the skin. Cellulitis and erysipelas manifest as areas of skin erythema, edema, and warmth in the absence of an underlying suppurative focus; unlike cellulitis, erysipelas lesions are raised, there is a clear line of demarcation at the edge of the lesion, and the lesions are more likely to be associated with fever. Cellulitis, on the other hand, is more likely to be associated with lymphangitis. Cellulitis and erysipelas are usually caused by β-hemolytic streptococci; S. aureus (including methicillin-resistant Staphylococcus) and gram-negative aerobic bacteria may also cause cellulitis. A recent study from France of 60 returned travelers with skin and soft tissue infections found 35% had impetigo and 23% had cutaneous abscesses. Methicillin-susceptible S. aureus was detected in 43%, group A Streptococcus in 34%, and both in 23%.

Emerging antibiotic resistance among staphylococci and S. pyogenes (erythromycin resistance) is problematic, because antimicrobial treatment may be more difficult. After return from travel, antibiotic choice will be determined by symptoms and extent of illness. If a skin problem occurs during travel, the antibiotic choice may depend on whether medical care and follow-up are available, as well as which medications are available. Some travelers may benefit from carrying an antibiotic for self-treatment in these circumstances. Choices are difficult but include trimethoprim-sulfamethoxazole, an extended-spectrum penicillin, a cephalosporin, a broad-spectrum quinolone, and azithromycin. None of these is ideal.

Another common bacterial skin infection in the tropics, due to S. aureus or S. pyogenes, is impetigo, especially in children. Impetigo is a highly contagious superficial skin infection that generally appears on the arms, legs, or face as “honey-colored” scabs formed from dried serum. The treatment of choice is a topical antibiotic such as mupirocin.

Myiasis presents as a painful, boil-like lesion. It is caused by an infection with the larval stage of the tumbu (Cordylobia anthropophaga) or bot fly (Dermatobia hominis). The larvae are frequently acquired in Africa and Latin America. The lesions reveal a small, central punctum that allows the larvae to breathe. Several techniques have been described for removal of the larvae; occlusion of the punctum with petroleum jelly is most often used.

Tungiasis is caused by a sand flea (Tunga penetrans). The female burrows into the skin, usually the foot, and produces a nodular, pale, subcutaneous lesion with a central dark spot. The lesion expands as the female produces eggs in her uterus. The flea must be extracted surgically.

Loa loa filariasis can rarely occur in long-term travelers living in rural sub-Saharan Africa. It is transmitted by day-biting deer flies. The traveler may present with transient, migratory, subcutaneous, painful, or pruritic swellings produced by the adult nematode migration. Rarely, the worm can be visualized crossing the conjunctiva of the eye or eyelid. Eosinophilia is common. Loa loa can be diagnosed by finding the larval stages (microfilaria) in blood collected during the day. Serologic tests are also available but usually not in commercial laboratories. Infection can be prevented by taking 200 mg of diethylcarbamazine once a week while at risk.

Gnathostomiasis is a nematode infection found primarily in Southeast Asia and less commonly in Africa and Latin America. Infection results from eating undercooked or raw freshwater fish. The traveler experiences transient, migratory, subcutaneous, pruritic, or painful swellings that may occur weeks or even years after exposure. The symptoms are due to worm larva(e) migrating throughout the body, including the central nervous system. Eosinophilia is common, and the diagnosis can be made by serology.

MACULAR LESIONS

By far the most frequent macular lesions seen in returned travelers from warm climates are superficial mycoses, such as tinea versicolor and tinea corporis.

Tinea versicolor, which is due to Malassezia furfur (previously Pityrosporum ovale), is characterized by asymptomatic hypopigmented or hyperpigmented oval, slightly scaly patches measuring 1–3 cm, found on the upper chest, neck, and back. Diagnosis is by Wood’s lamp or by placing a drop of methylene blue on a slide onto which clear cellulose acetate tape is placed sticky side down, after it has been touched briefly to the skin lesions to pick up superficial scales. Hyphae (“spaghetti”) and spores (“meatballs”) are readily visible. Treatment with topical or systemic azoles (ketoconazole, fluconazole) or terbinafine is recommended.

Tinea corporis (ringworm) is caused by a number of different superficial fungi. The lesion is often a single lesion with an expanding red, raised ring, with a central area of clearing in the middle. Treatment is several weeks’ application of a topical antifungal agent.

Lyme disease, a tickborne infection with Borrelia burgdorferi, is common in North America, Europe, and Russia (see Chapter 3, Lyme Disease). The traveler presents with one or more large erythematous patches, with or without central clearing, surrounding a prior tick bite. The patient may not have noted the tick bite.

LINEAR LESIONS

Cutaneous larva migrans is usually the result of infection of the skin with a larva from a dog or cat hookworm (most often Ancylostoma braziliense) but can also be caused by infection with other helminth parasites such as Strongyloides stercoralis (see Chapter 3, Cutaneous Larva Migrans). Dogs and cats that defecate on beaches appear to be one of the main risks for travelers. Lesions appear on the feet or buttocks most commonly. The traveler presents with an extremely pruritic, serpiginous, linear lesion that migrates within the skin at the rate of 2–4 mm per day. Treatment is with oral albendazole or ivermectin.

Phytophotodermatitis results from spilling lime juice onto the skin in a sunny climate. The result is an exaggerated sunburn that gives rise to a linear, asymptomatic lesion that later develops hyperpigmentation. The hyperpigmentation may take weeks or months to resolve.

Lymphocuticular spread of infection occurs when organisms spread along superficial cutaneous lymphatics, producing a raised, linear, cordlike lesion; nodules or ulcers may also be found. Examples include sporotrichosis, Mycobacterium marinum (associated with exposure to water), leishmaniasis, bartonellosis (cat-scratch disease), tularemia, and blastomycosis.

SKIN ULCERS

Ulcerated skin lesions may result from Staphylococcus infections or may be the direct result of an unseen spider bite. Often the cause of such an ulcer is not clear. Of particular concern is the ulcer (or nodule) caused by cutaneous leishmaniasis, which results from the bite of a sand fly. The main areas of risk are Latin America, the Mediterranean, Middle East, Asia, and parts of Africa. The lesion is a chronic, usually painless ulcer, unless superinfected, with heaped-up margins on exposed skin surfaces. Special diagnostic techniques are necessary to confirm the diagnosis. Both topical and systemic treatments are effective; the species of the infection often determines the treatment modality. If cutaneous leishmaniasis is suspected, clinicians can contact CDC for further advice about diagnosis and treatment (see Chapter 3, Leishmaniasis, Cutaneous for contact information).

MISCELLANEOUS SKIN INFECTIONS

Skin Infections Associated with Water

Soft tissue infections can occur after both freshwater and saltwater exposure, particularly if there is associated trauma. Puncture wounds due to fishhooks and fish spines, lacerations due to inanimate objects during wading and swimming, and bites from fish or other sea creatures may be the source of the trauma leading to waterborne infections. The most common soft tissue infections associated with exposure to water or water-related animals include M. marinum, Aeromonas spp., Edwardsiella tarda, Erysipelothrix rhusiopathiae, and Vibrio vulnificus. A variety of skin and soft tissue manifestations may occur in association with these infections, including cellulitis, abscess formation, ecthyma gangrenosum, and necrotizing fasciitis. Most Vibrio infections occur in men; V. vulnificus may be especially severe in those with underlying liver disease. M. marinum lesions usually appear as solitary nodules or papules on an extremity, especially on the dorsum of feet and hands that subsequently progress to shallow ulceration and scar formation. Occasionally, “sporotrichoid” spread may occur as the lesions spread proximally along superficial lymphatics.

“Hot tub folliculitis” due to Pseudomonas aeruginosa may result from the use of spa pools or whirlpools or exposure to inadequately chlorinated swimming pools and hot tubs. Folliculitis typically develops 8–48 hours after exposure in contaminated water and consists of tender, pruritic papules, papulopustules, or nodules. Most patients have malaise, and some have low-grade fever. The condition is self-limited in 2–12 days; typically no antibiotic therapy is required.

Skin Infections Associated with Bites

Wound infections after dog and cat bites are caused by a variety of microorganisms. S. aureus; α-, β-, and γ-hemolytic streptococci; several genera of gram-negative organisms; and a number of anaerobic microorganisms have all been isolated. The prevalence of Pasteurella multocida isolates from dog bite wounds is 20%–50%; P. multocida is the major pathogen in cat bite wound infections. Management of dog and cat bites includes consideration of rabies prophylaxis, tetanus immunization, and antibiotic prophylaxis. Primary closure of puncture wounds and dog bites to the hand should be avoided. Antibiotic prophylaxis for dog bites is controversial. Since P. multocida is a common accompaniment of cat bites, prophylaxis with amoxicillin-clavulanate or a fluoroquinolone for 3–5 days should be considered.

FEVER AND RASH

Fever and rash in returned travelers are most often due to a viral infection. Dengue is the most frequent and perhaps most easily recognizable example.

Dengue fever is caused by 1 of 4 strains of dengue viruses (see Chapter 3, Dengue Fever and Dengue Hemorrhagic Fever). The disease is transmitted by a day-biting Aedes mosquito often found in urban areas. The disease is characterized by the abrupt onset of high fever, frontal headache (often accompanied by retroorbital pain), myalgia, and a faint macular rash that becomes evident on the second to fourth day of illness. A petechial rash may be found in classical dengue, as well as dengue hemorrhagic fever. Serologic tests are available to diagnose dengue but often require a convalescent-phase serum sample to confirm. Nonsteroidal anti-inflammatory drugs should be avoided because of the increased risk of capillary leakage.

Chikungunya fever, a virus transmitted by a day-biting Aedes mosquito, has recently caused major outbreaks of illness in southeast Africa and South Asia (see Chapter 3, Chikungunya). Chikungunya fever is similar to dengue clinically, including the rash. The major distinguishing feature is that arthritis is common with chikungunya fever and may persist for months, whereas in dengue, arthralgia is the frequent joint problem. Similar to dengue, serologic tests are available for diagnosing chikungunya but often require a convalescent-phase serum sample to confirm. Treatment of the arthritis is with nonsteroidal anti-inflammatory drugs.

South African tick typhus, or African tick-bite fever (Rickettsia africae), is the most frequent cause of fever and rash in southern Africa. Transmitted by ticks, the disease is characterized by fever and a papular or vesicular rash associated with localized lymphadenopathy and the presence of an eschar (a mildly painful 1- to 2-cm black necrotic lesion with an erythematous margin). Diagnosis can be suspected clinically and confirmed by serology. Treatment is with doxycycline.

Rocky Mountain spotted fever (RMSF), although uncommon in travelers, is an important cause of fever and rash because of its potential severity and the need for early treatment. This tickborne infection is found in the United States, Mexico, and parts of Central and South America. Most patients with RMSF develop a rash between the third and fifth days of illness. The typical rash of RMSF begins on the ankles and wrists and spreads both centrally and to the palms and soles. The rash commonly begins as a maculopapular eruption and then becomes petechial, although in some patients it begins as petechial. Doxycycline is the treatment of choice.

The category of fever with rash is large, and travel medicine specialists should also consider the following diagnoses: enteroviruses, such as echovirus and coxsackievirus; hepatitis B virus; measles; Epstein-Barr virus; cytomegalovirus; typhus; leptospirosis; and HIV.

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