Smithsonian Scientist Bert Van Bocxlaer Uncovers New Links That Connects Environmental Changes with Spike in Infectious Disease
National Museum of Natural History scientist Bert Van Bocxlaer and an international team of researchers revealed that anthropogenic changes in Africa's Lake Mala?i are a driving force behind the increase of urogenital schistosomiasis, a debilitating tropical disease caused by parasitic flatworms. Scientists estimate that 250 million people are affected by schistosomiasis worldwide, and 600 million more are at risk of contracting it. In some villages along the shorelines of Lake Mala?i, 73 percent of the people and up to 94 percent of the schoolchildren are infected with urogenital schistosomiasis, one of several forms of the disease. Van Bocxlaer's research suggests that this spike in infection is directly linked to an increase in human populations and agricultural activities near Lake Mala?i, and may include a change in the dietary preferences of mollusk-eating fishes. Details from this study and recommendations to reduce the prevalence of urogenital schistosomiasis are published in the May 2014 issue of Trends in Parasitology.
Human population densities in Mala?i have more than doubled during the past 30 years, resulting in increased land use,overfishing and ecological changes that create a favorable environment for Bulinus nyassanus, a small freshwater snail that acts as an intermediate host of the disease-causing parasite. Infected snails release larval flatworms that can penetrate human skin upon contact with water. Humans are the definitive host and, upon infection, excrete eggs that hatch in water and infect snails such as B. nyassanus.
"Scientists have long known that environmental changes can affect public health, but our research reveals that human impact on the environment plays a larger role in the spread of schistosomiasis than previously thought," said Van Bocxlaer. "Decreasing the transmission of this infectious disease will require an integrated control program for schistosomiasis, including community-based health education with efforts toward more sustainable resource use."