[Rainfall and acute febrile syndrome in a dengue-endemic area]

Describing patterns of acute febrile syndrome (AFS) consultation related to dengue and evaluating association with rainfall.

318 undifferentiated AFS patients were detected in two clinics during a 7-month period (March to September) and then included in systematic clinical follow-up. 31 % of them (81/281) were IgM positive for dengue. Rainfall (litres/square meter-day) during the previous weeks was evaluated as a variable for predicting consultation patterns.

June, July and September were the months in which the greatest number of AFS cases occurred. Cases of dengue were only significantly more frequent during July. When evaluating the previous weeks' rainfall patterns, consultation for AFS was seen to be associated with the average rainfall registered 5 weeks beforehand and such association was independent of the institution and/or month (incidence rate ratio IRR=1,04; 1-1.08 95 %CI, p=0.045). On the other hand, 5 consecutive weeks' average rainfall was an independent predictor of consultation for dengue 4 weeks later on (RTI=1 ,6 ; 1,15-2,22 95 %CI, p=0.006). A linear relationship was thus proposed (regarding these sentinel clinics) between consultation for dengue and rainfall: lt/mt-day (5 weeks' average rainfall) X 0 ,72 (0,60-0,84 95 %CI, p<0.001) = cases for each 100 000 habitants per week (4 weeks later).

Studying rainfall could predict the pattern of consultation for dengue in endemic regions.