Socio-demographic and environmental factors associated with Aedes breeding places in Phuket, Thailand.

This study aimed to determine the socio-demographic and environmental factors influencing potential breeding sites of the dengue vector in Phuket Province. Three hundred houses were recruited by cluster random sampling for larval inspection. Of all the types of water containers, a high proportion of tires and discarded items were infested by Aedes larva (42% and 32%, respectively). Due to the abundance of water tanks, jars for using water and discarded containers (1.7, 2.1, 0.8 per house), these were the main breeding sites (0.29, 0.35, and 0.28 infested containers per house, respectively). Buddhists' houses were significantly more likely to have a larvae-infested flower vase than Muslims' houses. Townhouses had relatively few infested containers, while those on rubber plantations had 18.3 times higher odds of having at least one container with larva. No window screens increased the odds of larva infestation in the discarded containers by 4.2 times. With this information and given a reliable piped water supply, the number of water containers can be reduced to minimize the breeding places. Garbage should be properly disposed of. Screens should be installed, if possible. Buddhists should be advised on the proper protection of flower vases.

The climatic factors influencing the occurrence of dengue hemorrhagic fever in Thailand.

The aim of this study was to determine the independent effects of climatic factors: rainfall, temperature and relative humidity, on the occurrence of dengue hemorrhagic fever (DHF) in Thailand after adjustment for cyclical pattern. Data regarding monthly DHF reported cases by province, monthly rainfall, rain-days, average daily maximum temperature, average daily minimum temperature and average relative humidity, and mid-year province population from 1978 to 1997 (240 months) in 73 provinces were collected from various governmental departments. The general equation: Incidence of DHF = constant + trends + cyclic effects + climatic factors + noise was used as the statistical model. Out of 73 provinces examined, an increase in temperature was associated with a rise in the incidence of DHF in 9 provinces, whereas increased rainfall was associated with a decreased incidence of DHF in 7 provinces. Analysis by region shows that DHF incidence was negatively associated with extra rainfall in the southern region, but was positively associated with elevated temperatures in the central and northern regions. Variability in incidence was explained mostly (14.7% to 75.3%) by trend and cyclic change and much less (0.2% to 3.6%) by independent climatic factors.