After grueling, non-stop days of biking over mountains, crawling through caves and kayaking down rivers, the racers in the 2000 Eco-Challenge in Borneo thought their struggle against Mother Nature ended at the finish line. For many it didn't. Researchers at the Centers for Disease Control and Prevention (CDC) report that at least 25% of the participants from that race developed a severe disease, leptospirosis, after returning home, highlighting yet another risk in the increasingly popular sport of adventure racing. They report their results at the annual meeting of the American Society of Tropical Medicine and Hygiene.
It started about a week after the race ended in early September. The CDC received a few sporadic reports of leptospirosis from Idaho, San Diego and Los Angeles. All the cases, though, had one thing in common. The patient had just finished participating in the Eco-Challenge.
"Putting all this information together it became clear that many Eco-Challenge participants had developed this illness. The reports we were receiving suggested there were a lot of ill individuals," says Dr. Jim Sejvar of the meningitis and special pathogens branch at the CDC. "Based on those initial results we initiated a telephone survey. Through a collaborative effort we tried to reach as many of the participants as possible, gather information on any illness or symptoms they had experienced and identify risk factors associated with illness."
They were eventually able to reach and interview just under half of the 308 race participants. Of those they interviewed approximately 44% had experienced symptoms consistent with leptospirosis infection. The researchers believe the cause might have been in the river water.
"Several of the events including kayaking, swimming in the river and spelunking appeared to be risk factors for infection," says Sejvar. "The only independently significant risk factor, though, was swimming in the river. There were a number of participants who became ill who did not report swimming in the river, but it's possible they were exposed to river water during one of the other events."
Leptospirosis is caused by a bacterium and is usually transmitted to humans through water contaminated with urine from infected animals. It may take as long as one month for symptoms of illness to develop among persons infected with the bacterium responsible for leptospirosis. The most common symptoms of leptospirosis include fever, chills, red eyes, abdominal discomfort, vomiting, and diarrhea. In rare instances, severe disease can result in damage to the liver, kidneys, and lungs.
Antibiotics are useful in both the prevention and treatment of leptospirosis. Several studies show that taking the antibiotic doxycycline just before or after exposure will not necessarily prevent infection, but can significantly reduce the severity of symptoms.
The Eco-Challenge experience is not an isolated incident in the adventure travel - leptospirosis link, as evidenced by other reports at the same meeting. For instance, researchers from the University of Utah reported on the case of a young woman who developed leptospirosis after a 2-week kayaking trip in Ecuador. As the popularity of eco-tourism and adventure travel increase and more people participate in activities where leptospirosis is prevalent this type of outbreak has the potential for occurring more often, says Sejvar. That doesn't mean people should avoid adventure travel, though. After all, part of its allure is its inherent risks. But, adventure travelers should investigate and learn as much about the location to which they are traveling as possible, so that they can be fully aware of the infectious disease risks that they may encounter.
The American Society of Tropical Medicine and Hygiene (ASTMH) is the principal organization in the United States representing scientists, clinicians, and others with interests in the prevention and control of tropical diseases through research and education. Additional information on the meeting can be found at http://www.astmh.org/presskit.html.
Materials provided by American Society For Microbiology. Note: Content may be edited for style and length.
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