By Philip R. Fischer, MD, DTM&H

Professor of Pediatrics, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN

Dr. Fischer reports no financial relationships relevant to this field of study.

SYNOPSIS: Some adventure travel is associated with exposure to infectious pathogens. Some adventure-related illnesses can be prevented. Understanding the details of an adventure trip can help focus a differential diagnosis for ill returned travelers.

SOURCE: Gundacker ND, Rolfe RJ, Rodriguez JM. Infections associated with adventure travel: A systematic review. Travel Med Infect Dis 2017;16:3-10.

Extreme adventure sports are increasingly popular, and millions of people engage in adventurous activities during vacation travel. While risks of trauma with adventure sports are evident, the infectious risks of such activities have been less well characterized. Thus, Gundacker and colleagues performed a systematic review of the literature to collate information regarding risks for infection while engaging in adventure sports during travel.

Gundacker focused on the risks associated with water sports (such as rafting and surfing), caving, trekking, cycling, and skiing. A careful literature search yielded 116 relevant articles. Varying with geography, whitewater rafting, caving, and adventure races carried relatively greater risk for infection.

Whitewater rafters are at risk of leptospirosis. With rodents (and possibly dogs, cattle, bats, and sea lions) as a reservoir, leptospirosis exposure occurs in water contaminated with spirochete-infected urine. A Costa Rican outbreak occurred during the rainy season when water levels were particularly high, thus allowing water to wash over land areas that were contaminated with rodent urine. Adventurers were particularly at risk when they swallowed significant amounts of water. Prophylaxis with doxycycline (200 mg weekly for adults) is effective in preventing leptospirosis in travelers who anticipate exposures to contaminated water.

Rafters in Ethiopia and Uganda also have become ill with schistosomiasis. Up to half of participants on some studied trips have been infected. Drying off right after water exposure might decrease the risk of parasite penetration. Post-trip testing (three months after return) and treatment (praziquantel) can reduce the risk of long-term sequelae of Schistosoma infection.

Travelers in contact with rivers in rugged areas are at risk of gastrointestinal illnesses as well. Giardia and norovirus infections have been reported after whitewater rafting trips. Attention to ingesting only boiled, bottled, or purified beverages can reduce an individual’s risk, and careful stool hygiene can reduce risks to future travelers.

Rafters to areas of endemic mycosis have become ill with blastomycosis and histoplasmosis after contact with soil on riverbanks. Itraconazole can be effective treatment for mild cases, and amphotericin is used for severe illness.

Surfers, windsurfers, and kite-boarders are at risk of superficial trauma and lacerations. These skin lesions then can become infected with water-associated germs, including Vibrio, Aeromonas, Plesiomonas, and Erysipelothrix. Third-generation cephalosporins and quinolones can be effective against infections caused by these microbes. Slow-to-heal infected skin lesions might be due to Mycobacterium marinum.

Caving can include exposures to bird droppings containing Histoplasma and to bat saliva and/or urine containing rabies. Cryptococcal meningitis occurred in an immunocompromised caver in South America.

Adventure racers are exposed to extreme environmental conditions. Outbreaks of Campylobacter enteritis and norovirus gastroenteritis have been described in adventure racers, with approximately 800 individuals affected in a norovirus outbreak.

Hikers and trekkers are, of course, at risk of mosquito-borne illnesses in disease-endemic areas. Malaria, dengue, chikungunya, and Zika are of particular concern. Topical insect repellents (such as 20% picaridin and 25% diethyl-meta-toluamide [DEET]) can reduce insect bites for four to six hours. Repellent use also can protect against tick-borne illnesses. Hantavirus and tularemia also have been reported in trekkers.

Hikers and trekkers in developing countries and in wilderness areas also are at particular risk for travelers’ diarrhea. For symptomatic individuals, oral hydration is essential, and loperamide can reduce the frequency or diarrhea in adults. Antibiotics (usually azithromycin; quinolones also are helpful in areas where resistant Campylobacter is not common) can reduce the duration of travelers’ diarrhea but also carry a risk of fostering the emergence of multidrug-resistant organisms in the gastrointestinal tract; thus, current advice is to use an antibiotic only for severe episodes of travelers’ diarrhea.

Cyclists experiencing traumatic accidents involving soil contact are at risk of superinfection not only by skin flora but also by Sporothrix, Nocardia, and other microbes.