Epidemiological study of occurrence and transmission of bovine viral diarrhea virus in swine

Abstract

The Project will be conducted in three studies with the main purpose of elucidating important epidemiological characteristics of the Bovine Viral Diarrhoea vírus (BVDV) infection in swines. The objectives are: verify the occurence of BVDV infection in swines slaughtered in comercial slaughterhouses (study 1) and in swines breeded on subsistence farms (study 2); and induce experimental infection and evaluate the airborne, nose-to-nose and water transmission of the BVDV (study 3). Studies 1 and 2 will use the virus neutralization test to detect antibodies anti-BVDV 1 and 2. For study 1 the statistical analysis established sampling of 1000 samples of swine blood, that will be collected during the bloodletting moment, in a 45 days period. The data of the farms are going to be obtained from the Animal Transit Permission (GTA) which will allow to correlate the presence of risk factors with the disease. For study 2 the statistical analysis established the sampling of 360 samples of swine blood, which will be collected in the farms. A questionaire will be applied to investigate if there are any correlations between the occurrence or absence of the disease in the swine herd of a property with the sanitary conditions of the same. To calculate the data correlation, will be used the confidence interval, the Odds Ratio and univariate analysis. In study 3, three evaluations are going to take place to teste each possible transmission route. In these evaluations, control groups will be formed, together with a sentinel group and a infected group, each one of them cointaining 2 animals. Isolators made of stainless steel and glass, which creates a fully controled enviroment, are going to be used allowing the diferent transmission routes to be tested eliminating the possibility of external contamination. The infected group will receive an inocullum containing samples of BVDV-1, and are going to be maintened inside the isolator for 18 days. In this period, blood samples are going to be collected for viruneutralization test and RT-PCR, oral and rectal swabs samples will also be collected for PCR detection, and at the end of the 18 days period, the piglets are going to be euthanized and organs fragments will be collected for histopathology and RT-PCR, in a way that results will be enough to verify the BVDV-1 transmission among weaned piglets. (AU)