Weather forecast could predict cholera outbreaks

AFP: Scientists are closing in on a forecast model that may soon be able to predict future cholera outbreaks based on increases in temperature and rainfall, according to a study published Tuesday. An analysis of several years of past data in cholera-prone parts of Zanzibar, Tanzania, showed that when temperatures rose one degree Celsius, cholera cases were likely to double within four months, said scientists at the International Vaccine Institute in Seoul, South Korea.

A small increase in rainfall (200-milliliter or 6.7 ounces per month) also forecast that a "substantial increase could be expected within two months," said the research in the June issue of the American Journal of Tropical Medicine and Hygiene.

Cholera, a diarrhea-causing bacteria that can be lethal in vulnerable populations, often strikes without warning, and by the time symptoms arise it is often too late for vaccines to be effective. The disease is primarily spread through fecal contamination of food and water. The bacteria can live in the environment, so rising water levels may also make it easier for the illness to spread, particularly in impoverished areas with poor sanitation.

The researchers applied the same statistical model "used to study seasonal trends for other infectious diseases, such as malaria and dengue fever, to retrospectively predict the cholera case-load in the region for 2003 to 2008," said the study. "The predicted levels based on climate conditions closely matched actual cholera cases and outbreaks recorded in surveillance reports over the same time period."…

Scanning electron microscope image of Vibrio cholerae bacteria, which infect the digestive system., using a Zeiss DSM 962 SEM. From T.J. Kirn, M.J. Lafferty, C.M.P Sandoe and R.K. Taylor, 2000, "Delineation of pilin domains required for bacterial association into microcolonies and intestinal colonization", Molecular Microbiology, Vol. 35(4):896-910… License information at http://remf.dartmouth.edu/imagesindex.html: "These images are in the public domain. Do with them what you will."