Schistosomiasis identified in travelers despite brief exposure, high altitude
A group of 10 travelers from Israel were infected with schistosomiasis after a single, brief freshwater exposure at Nyinambuga Crater Lake in Uganda, where the altitude is 1,630 meters, researchers reported at the American Society of Tropical Medicine and Hygiene Annual Meeting.
“This outbreak proves that even at high altitude, Schistosoma mansoni may exist, despite previous studies claiming that there is protection from this disease at above 1,400 meters,” Eli Schwartz, MD, of Sheba Medical Center in Tel Hashomer, Israel, told Infectious Disease News. “Therefore, every traveler who has had a short exposure to freshwater sources in endemic areas should be tested for schistosomiasis and treated, even if at the presenting moment he or she is asymptomatic.”
After Schwartz and colleagues identified the index case, they conducted an epidemiological investigation of the entire tour group and found that all of the members had symptoms and positive serology for schistosomiasis. The most common symptoms were headaches, fever and weakness. Neck pain also was present in 70% of the group, but this is not a known symptom of the disease, the researchers said.
Schwartz said ecologic changes and illegal fishing, typically by using mosquito nets, may have changed the epidemiology of schistosomiasis in the crater lakes. When S. mansoni reappeared in Lake Malawi, the explanation was that overfishing led to declines in the number of fish, which resulted in the proliferation of the host snail population. He also said health officials should explore the role of fish protection as a biological tool to control schistosomiasis.
“We call on the medical and public health community for further investigation, keeping in mind that protecting the fish population might serve as an important tool for schistosomiasis control,” Schwartz said. “Instead of looking for highly expensive and advanced methods of controlling the disease, such as vaccine production, we should use a biological tool that is easily available.”
For more information:
Schwartz E. #LB-2152. Presented at: American Society of Tropical Medicine and Hygiene Annual Meeting; Nov. 13-17, 2013; Washington, D.C.
Disclosure: Schwartz reports no relevant financial disclosures.