The idea of hookworms makes you shudder, consider this: Those pesky intestinal parasites may actually help your body ward off other infections and even prevent autoimmune and other diseases.
Studying members of the Tsimane, an indigenous population in the lowlands of Central Bolivia, UC Santa Barbara anthropologists Aaron Blackwell and Michael Gurven found that individuals infected by helminths -- parasitic worms -- were less likely than their counterparts to suffer from giardia, an intestinal malady caused by a flagellated protozoa. Similarly, those with giardia tended to be less infected by helminths. The researchers' findings appear in the Proceedings of the Royal Society B
Treatment of one parasite also led to a greater likelihood of having the other later, the researchers found. The study used longitudinal data on 3,275 Tsimane collected over six years, which thereby permitted the authors to make more definitive causal inferences. This represents a distinct improvement over common correlative studies.
"People living in developing countries are often burdened by simultaneous infections," said Blackwell, an assistant professor of anthropology and the paper's lead author. "The key finding in this study is that worms and giardia have antagonistic effects on one another, such that infection with one limits infection with the other."
The researchers' findings also suggest that treating one infection might allow the other to run rampant, which raises questions about currently accepted protocols for dealing with parasites.