Seasonal effects on the reported incidence of acute diarrhoeal disease in northeast Thailand.

ABSTRACT

PIP: Researchers compared data on acute diarrhea incidence with data on rainfall and temperature of 10 provinces and 15 districts of Khon Kaen province in northeast Thailand to determine the link between seasonal weather patterns and reported incidence of acute diarrhea. The relative incidence of diarrhea decreased with age in the winter while it increased with age in the hot season and early in the rainy season. Indeed reported incidence of diarrhea peaked in January for children 2 years old. The researchers suggested that rotavirus was the leading causative agent in this age group since it is common in cooler months and in children 2 years old. Another peak occurred in April-June when temperatures are high and early in the rainy season. This peak involved mainly adults. The researchers believed enterotoxigenic Escherichia coli, Campylobacter jejuni, and Shigella were the leading causative agents. The researchers posed a possible explanation for this April-June peak. In the beginning of the wet season, households changed their water source from groundwater to rainwater and began to use it differently. Further, they often stored water separately from rainjars. It was more likely that this water was more contaminated than stored rainwater or groundwater. In addition, fecal bacteria transmitted by food preparation and utensil handling and the rising humidity fostered its growth. These events may have accounted for the increased incidence of diarrhea in the early rainy season. A steep reduction in diarrhea incidence occurred around the middle of the wet season (July and August). Research has shown that increased water quantity may be better in reducing diarrhea incidence than only improving water quality. Furthermore, it also demonstrated that bacteriological quality of water stored in rainjars was better than water from shallow wells.