ABSTRACT
Leptospira spp. serovar Hardjo infection is endemic in Brazilian cattle herds. The main risk factors for infection by serovar Hardjo are introduction of infected bovine into free herds, access to surface water and grazing sheep and cattle together. The present study investigated the risk factors involved in serovar Hardjo infection in sheep-only herds and in sheep grazing together with cattle herds in the region of Sorocaba, state of São Paulo, Brazil. Serum samples from eight herds not vaccinated against leptospirosis, five consisting of cattle and sheep and three with sheep only, were examined by microscopic agglutination test. An epidemiological questionnaire was applied taking into account sanitary and zootechnical management and environmental conditions. All herds showed reactors to Leptospira spp.: 51.16% (22/43) in cattle-sheep herds and 70.83% (17/24) in sheep-only herds (p = 0.191); but only the cattle-sheep herds showed at least one reactor to the serovar Hardjo, which was absent in all the sheep-only herds. Grazing cattle and sheep together was the only significant risk factor for serovar Hardjo infection (p = 0.018). When the total of sheep raised in sheep-only herds was compared with those raised with cattle, the risk associated with grazing these species together was significant for the presence of serovar Hardjo (p = 0.005). It was concluded that serovar Hardjo in sheep was directly related to the presence of bovines, regardless of other risk factors.
KEY WORDS
Leptospira spp. sorovar Hardjo; sheep-bovine grazing together; leptospirosis risk factors