Intensity of Rainfall and Severity of Melioidosis, Australia

In a 12-year prospective study of 318 culture-confirmed cases of melioidosis from the Top End of the Northern Territory of Australia, rainfall data for individual patient locations were correlated with patient risk factors, clinical parameters, and outcomes. Median rainfall in the 14 days before admission was highest (211 mm) for those dying with melioidosis, in comparison to 110 mm for those surviving (p=0.0002). Median 14-day rainfall was also significantly higher for those with pneumonia. On univariate analysis, a prior 14-day rainfall of 125 mm was significantly correlated with pneumonia (odds ratio [OR] 1.70 [confidence interval [CI] 1.09 to 2.65]), bacteremia (OR 1.93 [CI 1.24 to 3.02]), septic shock (OR 1.94 [CI 1.14 to 3.29]), and death (OR 2.50 [CI 1.36 to 4.57]). On multivariate analysis, rainfall in the 14 days before admission was an independent risk factor for pneumonia (p=0.023), bacteremic pneumonia (p=0.001), septic shock (p=0.005), and death (p<0.0001). Heavy monsoonal rains and winds may cause a shift towards inhalation of Burkholderia pseudomallei.