Via The New York Times: Catching Up With a Childhood Killer, Diarrhea. Click or tap through for the full article and many links. Excerpt:
Far from the world’s fears about Ebola and MERS, a quiet revolution is taking place in the diagnosis of a disease much more prosaic but far more threatening: childhood diarrhea. After pneumonia, diarrhea is the deadliest threat to infants worldwide, killing about 700,000 every year.
More than 40 pathogens — viruses, bacteria and parasites — cause diarrhea in children in developing countries. According to decades-old guidelines from the World Health Organization, these children should receive oral rehydration; intravenous rehydration if they cannot keep fluids down; and a zinc supplement.
The guidelines also say that children should receive antibiotics only when there is blood in their stool. At the time the recommendations were written, the best science indicated that blood was a sign of bacterial infection, and bacterial diarrhea is usually the most dangerous.
But bacterial causes are more common than had been realized, recent studies have found, and blood is not always present. And because many children with diarrhea do not receive antibiotics under W.H.O. guidelines, some experts say, many die or end up stunted by persistent infections that could have been cured.
First drafted more than 30 years ago, the guidelines “were developed based on what everybody thought at the time — that most diarrhea was viral, and if it was bacterial, it would probably have blood in it,” said Dr. Jeffrey M. Pernica, a pediatrician at McMaster University Medical School in Canada.
With the advent of improved diagnostic technology, he added, “Now we can tell who’s really got what.”
A major study into causes of childhood diarrhea, the Global Enteric Multicenter Study published in 2013, found the top five to be rotavirus, the Cryptosporidium parasite, two different strains of E. coli bacteria, and Shigella bacteria. In various countries, other bacteria — including Aeromonas, Campylobacter and Vibrio cholerae, the cause of cholera — were also important.
“Actually, blood is a very poor marker” of bacterial diarrhea, said Dr. David M. Goldfarb, a microbiologist at the University of British Columbia who led a recent study of children’s diarrhea in Botswana and advocates changing the guidelines. “And it does not predict death.”
In diarrhea, time is crucial. Infants often arrive at hospitals close to death from dehydration, so quick decisions must be made. When the cause is viral, doctors can only hope the immune system kills the virus. Various bacterial infections are treated with various antibiotics. Parasites must be killed with other drugs.
Accurate diagnosis once took days. Stool samples were frozen and shipped to labs for microscopic evaluation or antibody tests. Clinics in poor countries, unable to do all that, used the simple W.H.O. guidelines.
But the price for not providing antibiotics when they are needed can be high. Repeated bouts of diarrhea flush nutrients out of the intestines and leave victims physically and intellectually stunted. Children who are chronically malnourished before age 2 grow up to do worse in school, are shorter than normal, and as adults give birth to smaller infants.