is a parasitical disease spread by poor sanitation. It's widespread and causes both acute and chronic injury. For decades, governments and donor nations have devoted countless dollars and hours to controlling this disease - mostly without success.
Epidemiologist Archie Clements from the University of Queensland in Australia wanted to know what works, what doesn't and why. He looked at the example of control efforts in the West African country of Mali.
In the 1980s, the Malian government initiated a widespread program to control schistosomiasis. It repeated the program again between 2004 and 2006.
Clements examined data from both control efforts. He was able to create maps of the distribution of the disease before and after both programs and he found that the distribution of schistosomiasis after 2006 was similar to the distribution before the original 1980s control program.
"[This] suggests that even though that control program might have been very successful at reducing illness as a result of schistosomiasis in the population that they targeted, there has not been an ongoing effect in subsequent generations of Malians," Clements says.
Schistosomiasis is easy to treat. It can be cured with one dose of a relatively cheap medicine called praziquantel. But, once cured, a person can easily become re-infected by swimming or bathing in water where the parasite is present. And children who live in that environment become continually re-infected.
"They get cumulative effects of these infections, and they eventually end up with horrible chronic illnesses, including damage to their bladder wall, damage to their kidneys, with the intestinal form, damage to the liver, and even they can die," Clements says.
Governments in China, Egypt and Brazil have initiated successful schistosomiasis control programs. But success has its cost: Those programs involved making major improvements to infrastructure, improving things like water, hygiene and sanitation in high-risk areas.
"There has got to be a combination of continuing the current strategy of administration of praziquantel but having a very long-term strategy and a very long-term commitment from international donors for doing that," Clements says.
Clements says programs without long-term investment don't succeed, and they end up costing more in the long run, since they have to be repeated. He says governments and donors would do better at controlling schistosomiasis if they made long-term commitments to multi-faceted programs that change the environment so the parasite can't flourish
Clements' research is published in PLoS Neglected Tropical Diseases.