Schistosomiasis (also known as snail fever or bilharzia) is an illness that develops when people come into contact with water contaminated by certain snails carrying the disease-causing parasites, which penetrate the skin and move through the body.

Schistosomiasis mass drug administration status for school-age children (2016)

Preventive chemotherapy coverage

WHO roadmap target:

Control by 2020

  • Control morbidity and achieve treatment coverage of at least 75% of all school-age children by 2020
  • Regional elimination in the Eastern Mediterranean Region, the Caribbean, Indonesia and the Mekong River Basin by 2015
  • Regional elimination in the Americas Region, Western Pacific Region and in selected countries in the African Region by 2020

There has been steady growth in population coverage with preventive chemotherapy for schistosomiasis globally over the past 5 years. Most impressive is the dramatic increase in coverage of school-age children with an extended donation of praziquantel. Coverage of children in 2016 was 53.7%, a 27% increase over 2015. The progress means that this fundamental indicator of controlling infection and disease is making progress towards the WHO target of 75%. Global population coverage, which includes adults, was however, only 34% in 2016, lagging behind the WHO roadmap target. This is due partly to a shortage of donated drugs for adults.


70.9 million children covered by schistosomiasis programmes 27% increase in coverage in 2016 over 2015

Progress towards elimination remains elusive as the challenge of truly stopping transmission becomes clear.

This coming year, the focus will be on continuing the increase in population coverage and improving morbidity control and impact assessments.

Guidance to programmes on achieving and measuring elimination is also required, as it is critical to understanding the frequency of treatment, the role of adults in transmission and morbidity, the focality of transmission for the best use of drugs and the best methods for measuring transmission. New guidance is available on vector control of snails, but new tools and approaches are needed.

The roles of WASH and behaviour change remain to be addressed. The incremental costs and benefits of these tools in both morbidity control and elimination should be debated as we extend the programme and use tools most effectively to achieve the targets.

This is part of Reaching a Billion, the fifth progress report of the London Declaration on NTDs. Read the full report.