Serological monitoring of vaccination against the major avian viral diseases in poultry breeding farms in Tunisia

Abstract

A sero-epidemiological study was conducted in six broiler breeding companies and four broiler breeding laying hen companies, covering most of the poultry breeding farms in Tunisia. The objective was to evaluate the effectiveness of the immune response following the application of vaccination protocols established by the owners and carried out against the viruses of Newcastle disease (NDV), infectious bronchitis (IBV) and infectious bursal disease (IBD). During eight visits per farm, questionnaires were completed and 2000 samples were taken. The samples were submitted to indirect ELISA using CIVTEST AVINDV, -IBV, and -IBD kits. For each date and each disease, the mean specific antibody titers and the coefficient of variation were calculated. These indicators revealed that the chicks were in good health, the kinetics of post-vaccination antibodies generally satisfactory, and the overall immune response sufficiently uniform. However, the vaccination protocol recommended by the National Commission for Avian Diseases was not always applied. This either caused a temporary drop in antibody levels resulting in a high risk of infection, or necessitated interventions resulting in economic losses because of vaccine-related costs. This work shows the need for farmers to have a database for the establishment of an immunoprophylaxis program adapted to the epidemiological conditions of these farms.