Sero-prevalence of peste des petits ruminants virus-specific antibodies in Sudanese sheep and goats before and after vaccination

Abstract

Abstract Peste des petits ruminants virus (PPRV) antibodies were studied in Sudanese sheep and goats (n = 855) before and after vaccination with a locally produced Nigeria 75/1 vaccine using a commercial competitive ELISA (cELISA) kit (IDvet Grabels). Animals were kept healthy under field conditions, in four states; Blue Nile (n = 250), North Kordofan (n = 189), South Darfur (n = 225) and the Northern State (n = 191). Before vaccination, sero-prevalence of PPRV antibodies was 54.6% (53.2%-56% 95% CI); high (64.8%-76.4% 95% CI) in South Eastern Sudan (Blue Nile), medium (50.5%-61.9% 95% CI) in Western Sudan (North Kordofan and South Darfur) and low (28.6%-35.2% 95% C.I) in Northern Sudan (Northern State). In high-risk areas (high sero-prevalence), Blue Nile (70.4%) and North Kordofan (57.7%), middle age groups (7–12 and 13–18 months) were identified as high-risk age. Middle age groups showed lower sero-prevalence than preceding (3–6 months) and subsequent (> 18 months) age groups while the risk of exposure increased with age. Current and previous findings suggested a transmission pathway of PPRV involving the South Eastern border (Blue Nile) and neighbouring Central Sudan to North Kordofan. One month after vaccination 88.4% (343/388) of sero-negative animals were sero-converted suggesting the efficacy of the locally produced Nigeria 75/1 vaccine. Had only the high- risk age group (7–18 months) was vaccinated, the overall population immunity (OPI) in high-risk areas (Blue Nile and North Kordofan) would have surpassed the threshold of 70% indicated for blocking PPRV transmission. However, lower vaccination coverage is expected in wider vaccination programme. findings justified targeting PPR control in Sudan, primarily, by vaccination of high-risk age groups in high-risk areas.