Rotavirus is a ubiquitous, equal-opportunity pathogen that infects rich children and poor, the hygienically correct and the unspeakably filthy alike. The vast majority of the 130 million children born each year in the world feel its gastrointestinal bite.

The good news is that the Food and Drug Administration recently licensed Wyeth-Ayerst Laboratories to market an oral vaccine against rotavirus in the United States, where the disease results in about 50,000 hospitalizations and perhaps 40 deaths a year. The bad news is that the vaccine may not be available for many years in the developing world, where the severe diarrhea and dehydration that accompany infection claim somewhere between 600,000 and 800,000 young lives a year.