Key Data

  • Globally, it is estimated that 232 million people in 78 countries require annual treatment for schistosomiasis. 
  • In the Region of the Americas, a total of 10 countries and territories are considered endemic for schistosomiasis and 25 million people are at risk. 
  • It is estimated that approximately 1.6 million school-aged children in the Region require preventive chemotherapy, primarily in foci located in northeastern Brazil and the center of Venezuela. 
  • Transmission of the disease is estimated to be very low in Suriname and Saint Lucia, and these countries may interrupt transmission in the near future. 
  • Antigua, the Dominican Republic, Guadeloupe, Martinique, Montserrat, and Puerto Rico may have successfully interrupted the transmission of schistosomiasis. The evidence should be evaluated and compiled in order to request validation of elimination of this disease from WHO. 
  • The American continent could be the first WHO region to achieve interruption of the transmission of this disease.

What is schistosomiasis?

Schistosomiasis is a chronic parasitic infection caused by parasitic worms. In the Americas, the only species found is Schistosoma mansoni, which is associated with intestinal schistosomiasis.

The main risk factor for infection is exposure through household, work, or recreational activities in fresh water contaminated with feces from infected humans. For transmission to occur, a type of snail (Schistosoma mansoni, the intermediary host for the parasite, must be present. 

This disease is chronic and can result in anemia, fibrosis of intestinal veins and the liver, splenomegaly, and in serious cases, may lead to neurological complications and death. Neurological complications are known as neuro-schistosomiasis. Deaths from schistosomiasis in children and adults are reported each year. 

The interventions recommended by PAHO/WHO mainly focus on improving health conditions and the mass administration of praziquantel in endemic areas, to entire communities or high-risk groups (school-age children, women of childbearing age, and workers in frequent contact with contaminated fresh water). Treatment at regular intervals prevents development and progression to more serious forms of the disease. 

PAHO/WHO's response

  • In 2012, the World Health Assembly adopted Resolution WHA65.21 urging endemic countries to reduce the transmission of schistosomiasis and accelerate its elimination.
  • In 2013, the World Health Assembly adopted Resolution WHA66.12 and reaffirmed the 2020 targets for 17 neglected tropical diseases, including schistosomiasis. 
  • PAHO/WHO provides technical cooperation for the surveillance, prevention, and control of schistosomiasis and helps countries prepare to obtain verification of elimination of transmission. 
  • PAHO/WHO offers antiparasitic praziquantel to countries at no cost, as well as diagnostic tests and technical support to move forward in mapping, implementation of activities, monitoring, and evaluation, with a view toward eliminating the disease.
  • In 2016, the PAHO/WHO Directing Council adopted ResolutionCD55.R9 aimed at implementing a plan for the elimination of neglected infectious diseases, including schistosomiasis.

Updated September 2017