Leptospirosis in dairy cattle from southern Brazil - risk factors

ABSTRACT

Background: Cattle are susceptible to chronic leptospirosis infection, that results in reduced milk production and reproductive disorders such as abortions, stillbirths, fetal malformation, and mummified fetuses, causing significant economic losses.Commercially available vaccines against leptospirosis offer limited protection to cattle because they contain only the mostprevalent serovars worldwide, even though they are not prevalent in the specific region. This study aimed to evaluate theprevalence of specific antibodies against Leptospira serogroups, reproductive disorders and the risk factors in dairy herdsfrom different mesoregions of Rio Grande do Sul State, Southern Brazil.Materials, Methods & Results: An epidemiological survey was conducted, and serum samples from the bovine population representative of three mesoregions (MR1, MR2, and MR3) were studied; the samples were collected and tested forleptospirosis using the microscopic agglutination test (MAT) for 12 serogroups checking for the presence of agglutination.A total of 442 blood samples were collected from dairy cattle from November to December 2019 (MR1, 187; MR2, 88;and MR3, 167), including cows vaccinated with different commercial vaccines during the three months before sample collection (n = 295) and non-vaccinated against leptospirosis (n = 147). At the time of collection, an interview was conductedwith the owners with questions about the health of the animals, management, habitat, feeding and reproduction. Chi-squaretests univariate analysis with the SPSS® version 20.0 were performed to estimate the association of serogroup Djasimanseroreactivity with the occurrence of reproductive problems and related risk factors. The mean prevalence of antibodiesagainst leptospires was 78.7% (MR1, 74.9 %; MR2, 84.1 %; and MR3, 80.2 %). Serogroup prevalence was different in...