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. 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.