ABSTRACT
Bluetongue (BT), caused by Bluetongue virus (BTV), is a disease that affects ruminants such as cattle, sheep, goats and deer. BTV is transmitted by female midges of the genus Culicoides. In Brazil, information on the prevalence of BTV in cattle is limited, so the objective of this work was to identify BTV serotypes in cattle. The State of São Paulo was divided into seven cattle-producing regions, and in each of them, 300 cattle farms were randomly selected. One animal from each farm (out of a total of 1,598 farms) was selected and its sera tested by virus neutralization technique against BTV serotypes (1-24 and 26) for determining antibody titre. Moreover, for each sampled farm, an epidemiological questionnaire was submitted to verify the type of cattle production and the zootechnical and sanitary practices carried out, which could be associated with a higher risk of BTV infection. In this study, antibodies (percentage, [95% confidence interval]) were identified against 11 serotypes: BTV-1 (22.15%, [15.72-27.92]), BTV-2 (31.03%, [26.65-37.98]), BTV-3 (18.96%, [12.42-24.90]), BTV-4 (24.90% [19.41-29.12]), BTV-9 (6.82%, [1.45-11.72]), BTV-12 (7.50%, [2.82-12.51]), BTV-17 (23.90%, [17.35-29.35]), BTV-19 (10.20%, [4.62-5.56]), BTV-21 (30.66%, [25.00-36.00]), BTV-22 (12.14%, [5.91-18.55]), BTV-26 (57.00%, [51.41-63.59]). In this study, for the first time in Brazil serological evidence of the presence of serotypes BTV-2, BTV-9, BTV-21 and BTV-26 is reported. The variable 'new cattle entering herd' was considered a risk factor for the occurrence of infection (OR = 2.183, 95% CI = 1.6-2.9).
Subject(s)
Bluetongue virus/classification , Bluetongue/epidemiology , Cattle Diseases/epidemiology , Animal Husbandry , Animals , Bluetongue virus/immunology , Brazil/epidemiology , Cattle , Cattle Diseases/virology , Cross-Sectional Studies , Logistic Models , Prevalence , Risk Factors , SerogroupABSTRACT
A cross-sectional study was carried out to determine the flock-level seroprevalence of Caprine herpesvirus 1 (CpHV-1) and Bovine herpesvirus 1 (BoHV-1) and 2 (BoHV-2) and risk factors associated with CpHV-1 in dairy goat flocks from a semiarid region of northeastern Brazil. A total of 1,034 serum samples from 110 flocks were collected from March 2009 through March 2010. A structured questionnaire focusing on variables related to risk factors for CpHV-1 infection was given to each farmer at the time of blood collection. Antibodies against CpHV-1, BoHV-1, and BoHV-2 were detected by neutralization tests. The flock-level prevalences of CpHV-1, BoHV-1, and BoHV-2 were 89.1% (98/110; 95% confidence interval [CI]: 81.7-94.2), 80% (88/110; 95% CI: 71.3-87), and 4.5% (5/110; 95% CI: 1.5-10.3), respectively. Frequencies of seropositive animals were 36.6% (379/1,034), 25.8% (267/1,034), and 0.6% (6/1,034) for CpHV-1, BoHV-1, and BoHV-2, respectively. The use of natural mating was identified as a risk factor associated with CpHV-1 flock-level prevalence (P = 0.001). It is suggested that adoption of veterinary services and active surveillance of the at-risk flocks in the study region should be initiated to reduce the prevalence of herpesvirus infections.