Effect of vaccination in lowering the prevalence of bovine brucellosis in the State of Mato Grosso, Brazil

Abstract

The study was conducted to verify the efficacy of the bovine brucellosis vaccination program implemented by the state of Mato Grosso, using prevalence as an indicator. The state was divided into four regions: Pantanal, Milk, Fattening, and Breeding. For each region, a predetermined number of properties were selected and blood samples were taken from randomly chosen female animals, aged 24 months or greater. Sera from the animals were initially screened with a buffered acidified plate antigen, and confirmed using complement fixation. In each property, a questionnaire was used in order to identify the risk factors associated with the disease. In the state, the prevalence rate of infected herds was 24.0% [21.3; 26.8] and the prevalence rate of infected animals was 5.1% [3.5; 7.2]. The prevalence rates of infected herds and animals in each region were as follows: 21.2% and 6.4% in the Pantanal region, 17.2% and 3.7% in the Milk region, 34.0% and 7.2% in the Fattening region, and 24.3% and 4.4% in the Breeding region. Bovine brucellosis in the state is associated with the introduction of breeding, herd size, pasture sharing, and farms used for mixed and beef purposes. Therefore, in order to improve control of bovine brucellosis, it is proposed that the state of Mato Grosso intensify its prophylactic program, primarily its vaccination strategy. There has been a reduction in the prevalence of infected herds since 2002; however, there remains a high prevalence of infected herds and animals throughout the state. Additionally, the use of non-inducing antibodies vaccine should be encouraged, especially in the Pantanal region where the management of the animals is complicated by the flood and ebb cycle. The state should make greater efforts to educate producers on how to assess the breeding animals for brucellosis before introducing them into their properties as well as avoid shared grazing among herds of unknown health conditions.