In regions where cholera is endemic, outbreaks often coincide with the rainy seasons. But why this waterborne bacterial disease routinely strikes at such times has been unclear.
Researchers working in Bangladesh now offer evidence that bacteria-attacking viruses hold the cholera microbe in check throughout much of the year. But during the monsoons, these viruses probably become diluted in swollen lakes and rivers, leaving the cholera microbe, Vibrio cholerae, without this natural enemy. When this happens, V. cholerae can bloom, causing an outbreak of disease, the researchers conclude in an upcoming Proceedings of the National Academy of Sciences.
Cholera causes severe diarrhea. When poor sanitation permits feces from a cholera patient to enter a water supply, the bacteria spread to other people.
To assess whether bacteria-attacking viruses, called phages, might explain the seasonality of cholera outbreaks, John J. Mekalanos of Harvard Me