Infant diarrhea in research spotlight.

Infant diarrhea in research spotlight

An upset stomach with diarrhea is never pleasant, whether associated with contaminated food or a virus. But while some cases are merely irritating, others can have serious medical implications. A group of viruses called rotaviruses cause serious diarrhea in young children, but often are difficult to identify.

In an attempt to track rotavirus-associated diarrhea and its importance in the United States, scientists at the Centers for Disease Control (CDC) in Atlanta analyzed three sets of national disease-surveillance data from 1982 through 1986 on diarrhea in children under 2 years of age. During the six-year study, they found that the disease peaked between November and April each year, whereas other diarrhea-associated diseases tend to occur during warmer months. "All etiology studies indicate that rotavirus is the only [intestinal] agent that causes winter seasonality,' says CDC's Mei-Shang Ho. Winter diarrhea due to rotavirus occurs most often in children aged 4 to 23 months. When trying to determine causes of diarrhea, physicians should consider this seasonal and age-dependent variability to be key evidence, says Ho.

The CDC study also included the first look at the geographic distribution and the severity of reported rotavirus outbreaks. Scientists report that Mexico City has the earliest peak season for rotavirus infection in North America, followed by Los Angeles and then other U.S. cities in an annual "wave' of rotavirus diarrhea that spreads eastward. They estimate that the virus causes 80 deaths and 65,000 hospitalizations in the United States each year.

Because of the possibility of serious fluid loss from rotavirus-caused diarrhea, researchers are attempting to develop a vaccine against the virus. A group at Johns Hopkins University in Baltimore and the National Institutes of Health in Bethesda, Md., is testing a vaccine made by combining genes from monkey rotaviruses with a gene from the human rotavirus. While the preliminary clinical trial did not test whether the vaccine can prevent infection, it did determine that the vaccine leads to antibody formation against rotaviruses, with few side effects. However, another study by scientists at the same institutions found that neither this nor another vaccine candidate using bovine rotavirus prevented rotavirus diarrhea among Navajo Indian infants.