| Summary: | Although the incidence of some infectious diseases (Malaria, Cutaneous Leishmaniasis (CL), and Schistosomiasis) in the Asir Region, Saudi Arabia, has decreased over the last decade, they still cause significant health problems. This study tests the hypotheses that there are relationships between climate variables (maximum, mean and minimum temperature, rainfall and relative humidity) and these diseases in Asir Region. Monthly malaria, CL and schistosomiasis cases and climate variable data were obtained for the study area between 1995 and 2006, 1996 and 2007 and 1998 and 2009 respectively. Multiple regressions on the number of cases of each disease were performed against the climate variables. The climate variables were lagged to account for time gaps between weather events and disease. Different relationships with climate may occur at different times of the year and so separate models were created for each season. Within Asir, there are two separate malaria endemic areas in the lowlands: Tehama of Asir (TA) and Tehama of Qahtan (TQ). The results revealed that in these areas, rainfall in the current and previous month was positively associated (P<0.05 and P<0.001 respectively) with an increase in malaria cases during the summer. This may be due to increased breeding and survival of vectors after the rainfall. Temperature was not an important factor. Temperature was the most important factor associated with CL cases in all Asir and in the highlands area during the summer and beginning of autumn. If the maximum temperature in the previous 2 to 4 months was elevated there were more cases (P<0.001). Rainfall also plays a role in CL transmission in the lowlands. There were more cases of CL if rainfall was elevated in the previous 1 to 3 months (P<0.05). Temperature was an important factor associated with schistosomiasis throughout Asir during the summer and beginning of autumn. If the maximum temperature in the previous 3 to 4 months was elevated, there were more cases of schistosomiasis (P<0.05). Rainfall also plays an important role in schistosomiasis transmission in the highlands. There were more cases if rainfall in the previous 6 to 7 months (P<0.005) was elevated. This occurs during spring and summer seasons Based on these findings and an understanding of how these diseases are affected by climate it should be possible to design an early warning system using the weather to predict each disease’s incidence. Therefore, the results of this study have important implications for policies to improve public health in this region.
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