Investigação de Infecção por Leptospira spp. e Neospora caninum em novilhas de corte.

Abstract

Leptospirosis and neosporosis are disorders capable of generating major economic losses for the beef cattle industry; the main clinical manifestations observed in cattle herds include abortions, stillbirths and weak calf, repeat breeding and retained placenta. For these reasons, the positive identification of these individuals among the cattle is important for making the most effective choices about control strategies. The present study intended to verify the occurrence of anti-Leptospira spp. and anti-Neospora caninum antibodies among cutting heifer on Capim Branco Experimental Farm, located in the municipality of Uberlândia, Minas Gerais, Brazil. Twenty-one Nellore heifers, which were never submitted to leptospirosis vaccinated, had their blood serum tested with microscopic agglutination test (MAT), intending to detect anti-Leptospira spp. antibodies, and also with ELISA test, intending to detect anti-Neospora caninum antibodies. The study was divided into two collects; the first one preceded breeding season and vaccination, and the last one preceded birth season. At the first collect, 55.55% of individuals tested positive for at least one Leptospira spp serovar (1:100), whereas 63% tested positive at the last collect. Meanwhile, 47.61% of individuals tested by ELISA were positive for N. caninum at the first collect and 88.88% at the last collect. The MAT results for leptospirosis diagnosis indicate the individuals were in contact with the agent, therefore produced the anti-Leptospira spp. antibodies, but this concentration used in the experiment does not make it possible to establish if these individuals are carrying the actual disease, although the clinical signs of abortion, repeat breeding and weak calf lead to the suspect of a reproductive illness installed on the flock. Such clinical signs may be aggravated for the presence of these anti-Leptospira spp. and anti-Neospora caninum antibodies, considering these agents have direct effect on the reproductive tract in bovines.