Seroprevalence and risk factors of bovine herpesvirus 1 infection in cattle herds in the state of Paraná, Brazil.

Epidemiological data describing bovine herpesvirus 1 (BoHV-1) infection in Brazilian cattle herds are scarce. A cross-sectional study was conducted in the state of Paraná between December 2001 and July 2002 with the objective of estimating the apparent prevalence of BoHV-1-seropositive herds and animals and identifying the potential risk factors for infection in farms with breeding animals in the state of Paraná in Southern Brazil. The state was divided into seven regions based on the livestock production dynamics of the different areas. Sampling was performed in two stages. Initially, herds were randomly selected, followed by a random selection of animals within the selected herds. Blood samples were collected from 14803 females, aged ≥24 months, from 2018 BoHV-1 non-vaccinated herds. Serum samples were tested for antibodies against BoHV-1 using an indirect enzyme-linked immunosorbent assay (ELISA). The apparent prevalence of seropositivity in the herds and animals in Paraná was 71.3% (95% CI: 69.3-73.3) and 59.0% (95% CI: 56.2-61.8), respectively. Multiple logistic regression analysis revealed that risk factors associated with the presence of the infection were as follows: beef herds [OR = 1.58 (1.12-2.23)], natural service [OR = 1.48 (1.02-2.14)], purchase of animals [OR = 1.90 (1.52-2.37)], pasture rental [OR = 2.24 (1.51-3.33)], existence of calving pens [OR = 1.56 (1.20-2.03)] and records of abortion in the last 12 months [OR = 1.45 (1.08-1.95)]. These results indicate that BoHV-1 infection is widespread in the state of Paraná.