Bryon Skinner/CDC

ScienceShot: Diarrhea Deaths Decoded

Every year, 800,000 children under age 5 living in the developing world die from a disease that's usually considered a mere annoyance in the West—diarrhea. But until now, there's been very little reliable data on the microbes behind all this mortality, as well as their precise effects on children's health around the world. In order to fill in these knowledge gaps, a team of scientists spent 3 years studying diarrheal diseases at seven sites in south Asia and Africa. The results were sobering: children with moderate-to-severe diarrhea (MSD) were 8.5 times more likely to die within 60 days than children not suffering from MSD, the researchers report today in The Lancet. What's more, children who survived their bout with MSD showed signs of stunted growth that could impair their future development. On a microbial level, the team was surprised to discover that a majority of childhood MDS cases were caused by only four pathogens: rotavirus (pictured), the parasite Cryptosporidium, a strain of the Escherichia coli bacteria known as ST-ETEC, and the bacteria Shigella. The fact that rotavirus tops the list is actually good news, since efforts are already underway to vaccinate at-risk children against the virus. But the appearance of the Cryptosporidium is more troubling—scientists had no idea the parasite, which is usually seen in HIV-positive patients, was causing so many cases of childhood MSD. They hope this new study will fast-track much needed research about how to protect against this under-studied bug.

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