Leptospirosis During Adventure Travel
Special Feature
On aug. 20, 2000, the ecochallenge sabah 2000 expedi-tion race began in Malaysian Borneo. This event attracted 76 four-person teams from 26 countries, and included 36 teams from the United States and five teams from Canada. The EcoChallenge race is an intense, multisport event requiring participants to trek through jungles, swim in open water, canoe and kayak in rivers and oceans, mountain bike, scuba dive, spelunk, and climb their way through 320 miles of Borneo wilderness. In the words of the EcoChallenge promotional material "competitors will navigate through ancient caves and paddle along winding rivers in indigenous Sampan canoes where herds of elephants, monkeys, crocodiles, and even the rare Sumatran rhino can be seen. Teams will trek and mountain bike along dense rain forest trails while orangutans and ancient tribes of once fierce headhunters will curiously watch their passing. Teams will sail through tropical seas to magical coral-fringed islands using the native Perahu outrigger canoes and even dive down to an underwater coral reef checkpoint. Teams will negotiate swift jungle rivers and rappel down cascading waterfalls using fixed ropes."1 The event ran from Aug. 20 to Sept. 3 with participants taking anywhere from 6-12 days to complete the course, racing nonstop. Forty-four teams completed the race. Further details about EcoChallenge can be found at www.ecochallenge.com.
Beginning in early September, racers began to present with an acute febrile illness to health care professionals in their home countries. Reports to the GeoSentinel network2 and to the Centers for Disease Control (CDC)3 quickly began to accumulate, and helped to describe the nature of the illness and the extent of involvement. Of 153 athletes interviewed by the CDC up to late October, 68 (44%) met the case definition of an illness characterized by fever with at least two of the following symptoms: chills, myalgias, headache, diarrhea, or conjunctivitis (M Cetron, CDC, personal communication). Thirty-seven percent of case patients were hospitalized with no deaths occurring. The typical clinical syndrome included fever and myalgias with proteinuria, mildly elevated liver enzymes, and an increased serum CK level. Based on the characteristic clinical syndrome combined with positive serology in 13 of 27 (48%) U.S. case patients, a diagnosis of leptospirosis was made. Other clinically similar tropical diseases, including malaria, were ruled out. Among multiple potential exposures, participants encountered severely flooded rivers beginning on Aug. 25. Exposure during the river swim was significantly associated with illness.
Comment by David R. Hill, MD, DTM&H
Leptospirosis is an uncommon, but well-recognized cause of acute febrile illness in both travelers and native inhabitants of temperate and tropical areas of the world.4-9 Leptospira spp. are motile spirochetes that infect both domestic and wild animals. Dogs, livestock, and rats are the most commonly infected animals throughout the world. Organisms can survive for long periods in the kidneys of animals and then are excreted in urine, contaminating water, mud, or moist soil. When humans come into contact with the organism by swimming in or drinking contaminated water, or being covered with mud, as can easily occur during adventure travel, organisms penetrate mucous membranes or cuts and abrasions and establish infection. Heavy rainfall facilitates the spread of organisms, because as water saturates the environment, leptospires become washed into surface water. During times of flooding, there have been well-documented increases in leptospirosis. Fiji and Thailand are currently experiencing outbreaks. Flooding in Nicaragua in 199510,11 and in Guatemala, Honduras, and Nicaragua in 1998, in association with Hurricane Mitch, led to a marked increase in cases. Leptospirosis is also well-recorded in adventure travelers occurring in river rafters in Thailand7 and Costa Rica.12 In the summer of 1998, triathletes in Illinois experienced leptospirosis following their swim in a rain-swollen lake.5,13 The outbreak in triathletes affected 11% of participants; based on preliminary information, this current outbreak in Sabah had an extremely high attack rate of more than 40%.
Following an incubation period of four days to 2-3 weeks, the illness begins abruptly and is characterized by fever, chills, myalgias, and headache. Conjunctivitis, abdominal pain, vomiting, and diarrhea are also seen. A severe illness known as Weil’s disease with renal and hepatic, and rarely pulmonary involvement, can be life threatening.
Although treatment of mild illness is controversial, the CDC was recommending therapy of mild disease with doxycycline 100 mg twice daily for a week.3 Severely ill, hospitalized patients should be treated with intravenous penicillin.14 Evidence from U.S. troops stationed in Panama indicated that prophylaxis with 200 mg of doxycycline weekly is effective.15
There are several points for travel medicine experts. The first point is to consider leptospirosis in the differential diagnosis of an acute febrile illness in returned travelers, particularly if they have had fresh water exposure through recreational activities such as diving, swimming, or river rafting, or through occupational exposure with work in rice fields, sewer systems, or with handling of potentially infected animals.
The second is to inform travelers of leptospirosis if their plans would put them at risk and to become involved as advisors to tour groups or adventure racing promoters to provide accurate information about tropical disease risk. There has to be improved communication between the travel industry and travel medicine providers. Organizers of adventure travel may not emphasize the risk of disease in favor of promoting the exciting nature of their trip. Indeed, leptospirosis had occurred several times previously in adventure racers, some of whom were racing again in 2000 EcoChallenge, but it does not appear that this disease was adequately considered by race organizers.16 Racers may not focus on tropical disease risk during their period of intense training and be more concerned about accident or injury.
Third, if a traveler will be at great risk for leptospirosis, they should consider prophylaxis with doxycycline 200 mg weekly. It will be of interest to see if EcoChallenge racers who may have been taking doxycycline either for chemoprophylaxis of leptospirosis or malaria were protected from illness.
Finally, the benefits of a global surveillance system for tropical or travel-related disease with rapid dissemination of information are clearly illustrated with this outbreak. Within days, the GeoSentinel network had identified cases presenting to three sites in three different countries. In conjunction with CDC and WHO, information was provided via tropical and travel medicine e-mail list serves and the Internet (CDC web site [www.cdc.gov/travel/], EcoChallenge web site, and ProMed17), so that physicians could identify illness and participants could receive appropriate evaluation and treatment. Earlier in 2000, this surveillance system helped to rapidly identify an outbreak of W-135 meningococcal disease in religious pilgrims who traveled to Mecca for the annual Hajj.18 Thus, travel medicine health professionals should consider joining the American Society of Tropical Medicine and Hygiene (www.astmh.org) and/or the International Society of Travel Medicine (www.istm.org) so that they can participate in this global information network. (Dr. Hill is Associate Professor of Medicine; Director, International Travelers’ Medical Service, University of Connecticut, Storrs, Conn.)
References
1. EcoChallenge 2000. Field notes about the 2000 race. http://www.ecochallenge.com/borneo/borneo.htm. Accessed on Oct. 13, 2000.
2. The GeoSentinel network is a global surveillance system with 26 sites throughout the world, coordinated by the Centers for Disease Control and the International Society of Travel Medicine. It can be contacted via e-mail at [email protected].
3. Centers for Disease Control and Prevention. Outbreak of acute febrile illness among participants in EcoChallenge Sabah 2000—Malaysia, 2000. MMWR Morb Mortal Wkly Rep 2000;40:816-817.
4. Hill DR. Leptospirosis in Nicaragua. Travel Medicine Advisor Update 1996;6:10-12.
5. Hill DR. Waterborne infectious disease outbreaks: Cryptosporidiosis and leptospirosis. Travel Medicine Advisor Update 1998;8:42-45.
6. Bia F. Symposium: Leptospirosis—a re-emerging disease. Travel Medicine Advisor Update 1998;8:5-7.
7. van Crevel R, et al. Leptospirosis in travelers. Clin Infect Dis 1994;19:132-134.
8. Farr RW. Leptospirosis. Clin Infect Dis 1995;21:1-8.
9. World Health Organization. Leptospirosis worldwide, 1999. Wkly Epidemiol Rec 1999;74:237-242.
10. Centers for Disease Control and Prevention. Outbreak of acute febrile illness and pulmonary hemorrhage—Nicaragua, 1995. MMWR Morb Mortal Wkly Rep 1995; 44:841-843.
11. Trevejo RT, et al. Epidemic leptospirosis associated with pulmonary hemorrhage—Nicaragua, 1995. J Infect Dis 1998;178:1457-1463.
12. Centers for Disease Control and Prevention. Outbreak of leptospirosis among white-water rafters—Costa Rica, 1996. MMWR Morb Mortal Wkly Rep 1997;46: 577-579.
13. Centers for Disease Control and Prevention. Update: Leptospirosis and unexplained acute febrile illness among athletes participating in triathlons—Illinois and Wisconsin, 1998. MMWR Morb Mortal Wkly Rep 1998;47:673-676.
14. Watt G, et al. Placebo-controlled trial of intravenous penicillin for severe and late leptospirosis. Lancet 1988;1:433-435.
15. Takafuji ET, et al. An efficacy trial of doxycycline chemoprophylaxis against leptospirosis. N Engl J Med 1984;310:497-500.
16. Levy B. Lurking dangers. Risk and reward in adventure racing. MountainZone.com. http://adventure.mountainzone.com/2000/afiles/risk/html/index_1.html. Accessed Oct. 13, 2000.
17. ProMed (Program for Monitoring Infectious Diseases) is an e-mail list serve alerting subscribers to developments in infectious disease throughout the world. To subscribe send a message to: [email protected], followed by: subscribe ProMed digest. It can also be accessed on the Internet at: http://www.promedmail.org.
18. Centers for Disease Control and Prevention. Serogroup W-135 meningococcal disease among travelers returning from Saudi Arabia—United States, 2000. MMWR Morb Mortal Wkly Rep 2000;49:345-346.
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