Seroprevalence of Leptospira in Bavarian cattle herds and detection of Leptospira in aborted fetuses.

摘要

The antibody prevalence of Leptospira was investigated in 3463 replacement cattle from 1213 randomly selected Bavarian dairy farms and mother cow herds. About three blood samples per herd, composed of animals of >6 months of age, were tested for Leptospira antibodies using microagglutination tests (MAT) with six serovars. The prevalence of animals with MAT-titres of >=1:100 were 1.04, 0.09, 0.75, 0.26, 0.00 and 0.14% for Leptospira interrogans serovar hardjo, L. interrogans serovar canicola [L. interrogans], L. interrogans serovar grippotyphosa, L. interrogans serovar icterohaemorrhagiae, L. interrogans serovar pomona and L. interrogans serovar bratislava, respectively. On the herd level, the prevalence of L. interrogans serovar hardjo was considered separate due to the enzootic character of the serovar in cattle. Assuming that the hypothesis had three negative sera out of replacement cattle, excluding those enzootically infected with L. interrogans serovar hardjo, the herds suspected to harbour L. interrogans serovar hardjo infections had a prevalence of 1.48% (18 out of 1213 herds). The 18 herds were all in the region of southern Bavaria along the Alps. In this region, the prevalence was calculated to be 5.86% with a confidence interval of 4.10 to 8.56% (binomial statistics; alpha =0.05). The remaining serovars had a spotted distribution over the country and had a prevalence of 1.98% herds (confidence interval 1.45-2.76%) containing at least one seropositive animal out of the three tested animals. The aborted fetuses (n=154) that were sent to the diagnostic laboratories by the veterinarians were investigated using a Leptospira-specific real time PCR. One fetus was tested positive for L. interrogans DNA, while the other isolation attempts had negative results. Sera of cows with abortion or their neighbouring cattle were obtained from 47 herds. In 7 (15%) of these herds, L. interrogans serovar hardjo specific antibodies (MAT 1:200-1:3200) could be detected.