Effects of rainfall on incidental and host-maintained leptospiral infections in cattle in a tropical region.

Abstract

This study investigated the effects of rainfall on incidental and host-maintained leptospiral infections in cattle in a tropical region. Serum and urine specimens were collected from 582 bovines in a slaughterhouse. Seropositivity during rainy seasons was 43.6% (158/362) and during dry seasons was 31.8% (70/220; P = 0.0047). Positivity by urine PCR in rainy seasons was 42.3% (153/362) and 33.2% (73/220; P = 0.0296) in dry seasons. Additionally, increases in rainfall rates had different effects on host-adapted (serogroup Sejroe) and incidental (all other serogroups) leptospiral infections. There was a significant increase in the number of cattle shedding Leptospira during the rainy season (CI 1.04-2.09; P = 0.0296), suggesting temporary (transient) urinary shedding of incidental serogroups. Incidental and host-maintained Leptospira infections in cattle require different diagnostic techniques and control strategies.