An estimated 1.6 million school-age children need treatment to prevent this chronic parasitic infection, which is endemic in four countries of the hemisphere

Washington, D.C., 27 October 2014 (PAHO/WHO) — Representatives of countries affected by schistosomiasis, a chronic parasitic infection, met last week in Puerto Rico to define a roadmap for halting transmission and verifying the elimination of the disease. Schistosomiasis affects primarily school-age children in rural areas of certain countries in the Americas.

The meeting in Puerto Rico, held Oct. 21 and 22, was organized by the Pan American Health Organization/World Health Organization (PAHO/WHO) and brought health officials from 10 historically endemic countries together for the first time since 2007.

An estimated 1.6 million schoolchildren in the Americas need preventive treatment for schistosomiasis, which causes anemia, fatigue, weight loss, cognitive impairment, and other chronic symptoms that perpetuate the cycle of poverty, especially in rural areas with limited access to water and sanitation services.

"In the fight against poverty and infectious diseases, the elimination of schistosomiasis is low-hanging fruit in the Americas," said Steven Ault, PAHO/WHO regional advisor on neglected infectious diseases. "We need to make the correct ethical choice and do this as quickly as possible to bring an end to this totally preventable disease."

The main risk factor for infection is exposure to freshwater contaminated with human feces carrying the parasite. For transmission to occur, the snail that serves as the intermediate host for the Schistosoma parasite must also be present in the contaminated water.

At the recent meeting, health authorities agreed that eliminating schistosomiasis is a priority and endorsed elimination as a goal called for by the 65th World Health Assembly in 2012. They analyzed progress achieved so far in fighting schistosomiasis and defined lines of action toward the verification of the disease's elimination. Presentations and discussions at the meeting showed that:

  • In Martinique, Puerto Rico, Montserrat and Antigua and Barbuda, transmission of the disease may have been eliminated. Information needs to be compiled to provide evidence for verification by PAHO/WHO.
  • Brazil, which has the largest population at risk of the disease, currently has a schistosomiasis control program that includes mass treatment in communities with more than 25% prevalence as well as active case finding and selective treatment of families in areas with lower prevalence, along with other control measures. Brazil has completed a national prevalence mapping exercise and developed a national plan that integrates control of other neglected infectious diseases as well.
  • In Venezuela, schistosomiasis control efforts are aimed at elimination of transmission and include mass preventive treatment in two municipalities where the majority of cases reside. In other historically endemic municipalities, in five provinces, cases will be diagnosed and treated individually.
  • In Suriname, a survey carried out in 2010 and subsequent case-finding have shown that transmission is low and focalized.
  • In Saint Lucia, an updated assessment of transmission is needed to guide any public health interventions that may be needed.
  • In the Dominican Republic, a 2013 survey of historically endemic areas found no cases of schistosomiasis, adding to the evidence that transmission has been interrupted.

Interventions recommended by PAHO/WHO focus mainly on improving sanitary conditions and access to safe water, environmental control and, in endemic areas and according to prevalence, mass administration of the antiparasitic drug praziquantel to entire communities or high-risk groups (school-age children, women of child-bearing age, and workers who have frequent contact with contaminated freshwater). Regular periodic treatment prevents the development of the disease and its progression to more severe forms.

Also during the meeting, experts discussed the need to update country epidemiological studies of the status of transmission of the disease and to monitor and evaluate control and elimination programs and their integration with programs for other diseases, to ensure optimal use of human and financial resources. They also discussed the need to document the efforts and achievements of historically schistosomiasis-endemic countries.