Evaluation of immune response of small ruminant flocks to ovine Pasteurellosis and Peste Des Petits Ruminants vaccines in North Shewa, Ethiopia

The present study was conducted to evaluate the flock immune response of small ruminants to ovine pasteurellosis Bio type A and Peste des petits ruminants (PPR) vaccines and to determine their effects on the morbidity and mortality of animals due to ovine pasteurellosis and PPR from October 2017 to November 2019 in selected districts of the north Shewa Zone, Ethiopia. A total of 553 serum samples were collected and examined by using the Competitive Enzyme-Linked Immunosorbent Assay and an indirect haemagglutination inhibition test for PPR and ovine pasteurellosis antibodies, respectively. Based on the results, the number of animals with an antibody titer of 1:10 after 28 days and six months of vaccinations of P. multocida Biotype A was 161 (93.1%) and 152 (81.7%), respectively. Also, the positive antibody level (i.e., percent of colour inhibition PI > 50) after 28 days and 12 months of PPRV vaccinations was 82 (86.3%) and 69 (69.7%), respectively. There was a statistical difference (p < 0.001) between the antibody levels after 28 days and six months of vaccination against ovine pasteurellosis and after 28 days and 12 months of vaccination (p <0.01) for PPRV vaccines. During three consecutive years of intervention, out of a total of 2350 study animals, 500 cases (21.3%) showed respiratory signs, out of which 45 (1.9%) died. The PPR and ovine pasteurellosis vaccines applied in the field were effective in developing antibodies above the threshold herd immunity level of 80% and 70% respectively.Periodic vaccination against ovine pasteurellosis and PPR according to the epidemiology of the diseases results in a significant reduction in morbidity and mortality of small ruminants. Therefore, the current ongoing efforts to control ovine pasteurellosis and PPR of small ruminants through vaccination should be encouraged and strict sero-surveillance and monitoring of these diseases should be done side by side