A serologic survey of rice-field leptospirosis in Central Luzon, Philippines.

Although human cases of leptospirosis have been reported from the Philippines, there is a lack of data on its prevalence. We therefore surveyed three rice-farming villages for the presence of leptospiral antibody. Out of 155 sera tested, 63 (43.6%) tested positive using the standard microagglutination test. Antibodies were more frequent in men than women (48 vs. 31%, respectively, p less than 0.01), and less common in the elderly. Exposure to leptospires occurs frequently in rice farmers, and leptospirosis is likely to be an underdiagnosed cause of both mild and severe febrile illness in the Philippines.