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Massive campaign against parasitic worm disease is cost-effective, new study shows

Schistosoma_mansoni2In 2014, I was fortunate to visit a lovely resort in Uganda on the edge of Lake Victoria, one of Africa’s great lakes. As my friends and I relaxed at a beachside café, nibbling on roasted goat and pizza, we looked longingly at the inviting waters that lapped at the shore. But I knew that I would be taking a huge risk simply by wading into these placid waters, as they are teeming with freshwater snails laden with tiny worms that can penetrate the body and cause serious health problems.

These Schistosoma worms are parasites that can inhabit various organs, causing potentially fatal damage to the bladder, kidneys and liver. Children infected with these worms typically suffer from anemia, malnutrition and cognitive deficits, as well as generalized abdominal discomfort. These and infections from other parasitic worms, known as helminths, are exceedingly common, afflicting more than 1.5 billion people across the globe.

But this doesn’t have to be the case. A new analysis by Stanford researchers shows it would be cost-effective to dispense more than a billion doses of low-cost medication across sub-Saharan Africa in a major campaign to knock out these parasitic infections.

“If we incorporate this new evidence, we can start to consider elimination of this as a public health problem,” Nathan Lo, a medical student and first author of the study, told me. “Substantial populations are not receiving treatment under current guidelines that could benefit under a cost-effective program.”

Currently, the World Health Organization recommends that school age children be given low-cost drugs for schistosomiasis when more than 50 percent in a community are infected. But the Stanford study shows that it would be economically feasible to treat these children when prevalence is just 5 percent. The researchers also found it would be cost-effective to treat school children when 20 percent are infected with the soil-transmitted helminths, such as hookworm and roundworm, which are found in dirt.

Moreover, the analysis shows it makes economic sense to expand treatment to both pre-school age children and adults, as they may also be afflicted by these parasites. These groups aren’t generally included in the WHO treatment guidelines. It’s especially important to treat adults as they can reinfect children through household contamination of soil and water supplies, Lo said.

Treatment is cheap — costing between 3 and 21 cents a pill, the researchers say. Most drugs now used in the developing world are donated by pharmaceutical companies. Now, it’s a matter of finding the best way to distribute these medications in heavily affected areas.

The study authors encourage the WHO to revise its treatment guidelines, written a decade ago, with an eye to making treatment more widely available to those who need it.

“The guidelines were based on the best judgments of experts at the time, but I think there’s fairly broad agreement that it’s time to revisit these in view of new data, analyses and priorities,” Jason Andrews, MD, the study’s senior author and an assistant professor of medicine at Stanford, told me.

The study appears today in The Lancet Infectious Diseases. In an accompanying editorial, two physicians from the Liverpool School of Tropical Medicine say the results show that 75 percent coverage should now be considered the minimum preventative treatment standard for the two drugs.

Previously: A new framework for expanding treatment guidelines for parasitic worm diseasesExploring the cost-effectiveness of treating parasitic-worm diseases and Figuring out a parasite's secrets - insights from studying Toxoplasma gondii
Photo by Waisberg

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