Seroprevalence and risk factors associated with within-flock transmission ofLeptospira interrogansin transhumant farming systems in Mexico

Abstract

SUMMARYA number of recent reports emphasize the risk of zoonotic diseases and the high degree of prevalence of asymptomatic animals infected withLeptospira interrogans. This report sought to assess the prevalence of antibodies to certain serovars ofL. interrogans, and to describe the association between seropositivity and risk factors associated with within-flock transmission in a mountainous region of Mexico. Overall seroprevalence toL. interroganswas 54·5% (95% confidence interval 48·3–60·7); the most frequent serovar was Icterohaemorrhagiae. The accumulation of placentas and fetuses at a site close to lambing paddocks can play a significant role as a risk factor for within-flock transmission ofL. interrogansin transhumant farming systems in the municipality of Xalatlaco. The high prevalence ofL. interrogansantibodies supports the hypothesis that natural foci of this zoonosis are present in sheep flocks in this area. These findings emphasize the need for planning and implementation of control programmes for ovine leptospirosis in Mexico and elsewhere.