Just four pathogens underpin most cases of serious diarrhoea in children — the second leading killer of
Rotavirus particles
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young children worldwide — according to a study published today in The Lancet.
Out of nearly 40 diarrhoea-causing microbes, the researchers identified four primary culprits: rotavirus, Cryptosporidium, a toxic type of Escherichia coli, and Shigella. The winnowing of the list could allow health experts to design targeted health campaigns.
“I think what we have done is allow doctors and public health experts to prioritize and potentially save thousands of lives,” says Karen Kotloff, a paediatrician at the University of Maryland, Baltimore, and first author of the study. Diarrhoeal diseases kill an estimated 800,000 young children each year, second only to pneumonia, which kills around 1.2 million.
The 3-year study began in 2007 and involved nearly 22,000 children under the age of 5 in seven locations in sub-Saharan Africa and south Asia — making it the largest study of its kind. Researchers enrolled children who sought treatment at local clinics for moderate-to-severe diarrhoea and took stool samples to identify the microbe that was causing their illness.
Topping the list is rotavirus, which is spread by contact with stools. Vaccines against the well-known pathogen already exist, and today, the government of India, in partnership with Bharat Biotech, announced promising phase III trial results for a new vaccine.
Cryptosporidium, on the other hand, was a surprise to many researchers. The protozoan infects humans and animals, and can spread in contaminated water as well as from contact with human and farmyard faeces. “This had never been on the agenda before as a major pathogen in this clinical situation,” says George Griffin, an infectious-disease researcher at St George’s University of London, UK, and a member of the scientific advisory committee for the study. Although one drug is available to treat Cryptosporidium, more research is needed to understand the disease, says Griffin.