Herd-level prevalence and associated risk factors for Mycobacterium avium subsp. paratuberculosis in cattle in the State of Paraíba, Northeastern Brazil

Abstract

A cross-sectional study based on a planned sampling was carried out to determine herd-level and animal-level prevalences, and to identify risk factors associated with herd-level prevalence for bovine paratuberculosis in the State of Paraíba, Northeastern Brazil. The state was divided into three sampling groups: sampling stratum 1 (mesoregion of Sertão), sampling stratum 2 (mesoregion of Borborema), and sampling stratum 3 (mesoregions of Zona da Mata and Agreste). For each sampling stratum, herd-level and animal-level prevalences were estimated by a two-stage sampling survey. In the first stage, a pre-established number of herds (primary sampling units) were randomly selected; in the second stage, a pre-established number of cows aged ≥24 months were randomly selected (secondary sampling units). Ten animals were sampled in herds with up to 99 cows aged over 24 months; 15 animals were sampled in herds with 100 or more cows aged over 24 months; and all animals were sampled in those with up to 10 cows aged over 24 months. In total, 2504 animals were sampled from 480 herds. Enzyme-linked immunosorbant assay (ELISA) test kits were used for Mycobacterium avium subsp. paratuberculosis (MAP) antibody detection. A herd was deemed positive for the presence of MAP if it included at least one positive animal in herds of up to 24 females, and two positive animals in herds with more than 24 females. The herd-level prevalence in the State of Paraíba was 34.5% (95% CI=30.2–39.1%), 26.6% (95% CI=20.2–34.2%) in the region of Borborema, 30.5% (95% CI=23.9–38.0%) in Agreste/Mata, and 41.4% (95% CI=34.0–49.1%) in Sertão. The animal-level prevalence was 10.7% (95% CI=7.3–15.4%) in the State of Paraíba, 7.9% (95% CI=5.2–11.7%) in the region of Borborema, 9.4% (95% CI=7.3–12.1%) in Sertão, and 13.9% (95% CI=6.2––28.3%) in Agreste/Mata. The frequency of seropositive animals per herd ranged from 6.7% to 100% (median of 20%). The risk factors identified were as follows: Sertão region (OR=1.9), more than 12 adult animals in the herd (OR=1.9), and not using maternity pens (OR=1.7). Our findings suggest that MAP herd-level seroprevalence in the State of Paraíba, Northeastern Brazil, is high, and support the idea that the use of maternity pens will be important for preventing transmission of MAP in the herds.