Prospective evaluation of Leptospira spp. infection in goats maintained in field conditions in the Caatinga biome, Brazil

The Caatinga biome occurs only in Brazil; however, there is no survey on leptospirosis using direct and indirect diagnostic tests in this region with goats maintained in field conditions. We conducted a prospective survey with paired sampling to evaluate the importance of carrier goats in the maintenance of disease. Based on sampling calculation, 60 goats (30 confined and 30 extensively reared) were randomly selected and monitored for three months during the rainy season with paired monthly biological sample collections. The animals underwent urine and vaginal fluid collection for microbiological and molecular diagnosis, and serum samples for serological diagnosis using the microscopic agglutination test (MAT). Overall, 45 (75%) animals were positive in at least one diagnostic method. Anti-Leptospira spp. antibodies were detected in all three sampling moments in 43 (71.7%) animals, antibody titers varied from 25 to 800, and most frequent serogroups were Australis in the 1st and 2nd blood collections (66.7% and 40.7%, respectively) and Cynopteri in the 3rd collection (52.6%). None of the animals tested positive in the microbiological diagnosis or the vaginal fluid PCR; however, five (16.7%) animals were positive in the urine PCR only in the confined group in the first collection. Two DNA urine samples were sequenced, demonstrating 99% similarity with Leptospira interrogans. Different diagnostic techniques for leptospirosis in goats raised under Caatinga biome field conditions are suggested, as well as further studies over a longer period with monthly collections to better understand the prevalence of Leptospira spp. and its variation over time.