Case Western Reserve professor explores schistosomiasis elimination in NEJM perspective

In the January 8, 2009 issue of The New England Journal of Medicine (NEJM), schistosomiasis expert Charles H. King M.D., Professor of International Health at the Center for Global Health and Diseases at Case Western Reserve University School of Medicine concludes global eradication of schistosomiasis is feasible if the current infection control strategy shifts to a proactive, comprehensive elimination strategy. Dr. King supports the community-based trial by Wang et al. as a viable model for interrupting disease transmission by using a combination strategy, including supplementary education and sanitation, with many secondary environmental benefits. Schistosomiasis, also known as "snail fever," is a chronic inflammatory disease affecting more than 207 million people worldwide, often in the poorest areas. The decades-long disorder has challenged researchers for many years. The 1980s offered the last major advance when a large scale drug delivery program proved effective in reducing the infectious burden and morbidity, yet this treatment-based success failed to stem the parasite's transmission. With subsequent study of transmission ecology, researchers now attribute the transmission to external factors such as "superspreaders" — very few people who are responsible for the majority of transmission; to "hot spots" of transmission where human-snail interaction is high; and to the ongoing infection of domestic and wild animals with the parasite.

Dr. King writes, "As Wang et al. show, in high-risk ecological settings, drug treatment alone may suppress transmission only partially. In such environments, any program based solely on drug delivery will need to be continued for decades (or perhaps indefinitely) to prevent a reemergence of infection and disease. It is only through the incorporation of additional strategies for interruption of parasite transmission that all forms of schistosomiasis-associated disease can be prevented."

Dr. King and his colleagues at the Center for Global Health and Diseases at Case Western Reserve University are part of a new movement to control and reduce schistosomiasis. In a 2005 meta-analysis published in The Lancet, [King CH, Dickman K, Tisch DJ. Reassessment of the cost of chronic helmintic infection: a meta-analysis of disability-related outcomes in endemic schistosomiasis. Lancet 2005;365:1561-9]. Dr. King and his colleagues examined the disease burden and found it was substantially greater than had previously been estimated by the medical community in global disease burden assessments. The risk of the disease's many subtle complications had been previously overlooked, causing as significant underestimation of the disease's true disability. Since then, Dr. King and team have advocated for a comprehensive approach to controlling the spread of this preventable and curable disease.

"If the process of schistosoma infection continues unchecked, its disabling effects in the context of rural poverty will always limit the potential benefits of drug-treatment programs while also necessitating that treatment continue indefinitely. Obviously, the elimination of schistosomiasis will be a long-term process requiring a long-term investment, but we must shoulder the necessary extra effort, including long-term planning intersectoral government coordination and decades-long commitment," concludes Dr. King.

Source: Case Western Reserve University