Prevalence and distribution of peste des petits ruminants virus infection in small ruminants in India

Peste des petits ruminants (PPR) is an acute febrile viral disease of goats and sheep characterised by mucopurulent nasal and ocular discharges, necrotising and erosive stomatitis, enteritis and pneumonia. The disease is endemic in India and causes large economic losses each year due to the high rates of mortality and morbidity in infected sheep and goats. The present study reports observations from 58 laboratory confirmed outbreaks of PPR and provides details of the prevalence of antibodies to PPR virus (PPRV) in 4,407 serum samples of small ruminants. Most of the clinical specimens used for the study originated from the northern and central parts of India. Serum samples used for the detection of antibodies to PPRV were derived from a greater number of regions within the country, however, these samples may not be a true representation of the target population (unvaccinated sheep and goats over 3 months old). Indigenously developed monoclonal antibody-based diagnostic kits were used for the detection of PPRV antigen (sandwich enzyme-linked immunosorbent assay [ELISA]) and antibody (competitive ELISA). Findings suggested that the disease outbreaks were more severe in goats than sheep and that the frequency of disease outbreaks was greater between the months of March and June (51.7%) as compared to other periods of the year. Based on the screening of the 4,407 sera samples, the antibody prevalence of PPRV in small ruminants in India was 33% (95% confidence interval: 32.3% to 33.7%). The prevalence of antibodies to PPRV was noted to differ between species (i.e. sheep versus goats), age groups and geographical regions. A greater proportion of the sheep (36.3%) versus the goat (32.4%) population was infected with PPRV. The distribution and prevalence of antibodies to PPRV among various age groups of animals indicated that goats were exposed at an earlier age than the sheep, suggesting that goats may be more susceptible to infection with PPRV. A greater number of positive cases were observed in the southern and southwestern part of the country (30%-60%) as compared to northern India (10%-30%). These findings may be correlated with variations in the sheep and goat husbandry practices within different geographic regions, the topography of different states and the socio-economic status of individual Indian farmers.