A new study shows that infection with hookworm, ringworm, and similar parasites can be dramatically reduced with a sanitation program.
The researchers found even installing simple latrines can cut infection rates in half.
Parasitic worms thrive in tropical and subtropical climates - areas that are home to some of the world's poorest communities.
At least one billion people are thought to be infected. Sanitary facilities are frequently non-existent in these communities, and when infected people defecate in the open, the infection can spread to others who eat raw, unwashed vegetables or even just walk barefoot on contaminated soil.
The World Health Organization has endorsed a program of preventive medication. The pills, given once or twice a year, are very effective. But researcher Jürg Utzinger, of Switzerland's Tropical and Public Health Institute, says that's not enough.
"Problem with this strategy is of course, after successful de-worming, the next day you can become re-infected," he said.
Removing the source of the infection can have an immediate and more lasting impact. Utzinger and his colleagues analyzed three dozen published studies and reported their findings in PloS Medicine.
"And what we then found [was] that people having access and use of sanitation facilities are approximately at half the risk of an infection than those people without sanitation facilities."
And when he talks about sanitation facilities, he's not talking about flush toilets. The studies indicate that even the very simplest and cheapest facilities - pit latrines - can have a dramatic impact on parasite infection rates.
Utzinger stresses that the biggest impact in combating parasite infection comes from combining different strategies.
"And we need preventive measures, and sanitation is clearly one way forward. So then, the combination of sanitation, along with the drug component, [and] health education, this really should be the way forward."
Utzinger points out that these kinds of parasitic worms were once common in the southeastern United States, a region that was desperately poor until the mid-20th century. The fact that public health programs successfully eradicated these soil-transmitted parasites suggests that eliminating them in places like sub-Saharan Africa and Southeast Asia is an achievable goal.