Epidemiology of peste des petits ruminants in small ruminants of Punjab

Abstract

Among viral diseases , Peste des Petits Ruminants (PPR) is one of the main transboundary small ruminant diseases. PPR is an acute disease, highly contagious with clinical signs of high grade fever, occulonasal discharge, necrotizing and erosive stomatitis, intestinal mucosal damage and pneumonia, with morbidity and mortality rate 100 and 90% respectively. Present study was designed to conduct seroepidemiological study of PPR virus in sheep and goat in the Punjab province. A total of 800 serum samples were collected from selected areas from sheep (n=400) and goat (n=400) from population of the selected areas. In the five districts including Faisalabad, Attock, Dera Ghazi Khan, Bhakkar, Kasur were sampled and the samples were divided proportionately based on population size of the respective districts. Results showed that disease frequency was higher during winter days and maximum seroprevalence was detected in December, followed by May and September the trend was observed to decline in the month of July. Different risk factors affecting prevalence of PPR were investigated by the help of Participatory epidemiological investigations. Further, with the help of molecular epidemiology and by using PPRV specific F gene the molecular nature of the virus was analyzed. Moreover, the efficacy and protective ability of PPR vaccines under field conditions were evaluated in sheep and goats. The first part of the study focused upon investigating the epidemiological parameters and its association with the PPR disease in Pakistan. The second part of my study focused to detect the anti-PPRV antibodies in sheep and goat population in Pakistan. The serum samples were subjected to c-ELISA to detect antibodies directed against the nucleoprotein of the Peste des Petits Ruminants (PPR) virus The overall seroprevalence calculated on the basis of c-ELISA was found to be 61 % in sheep and 44% in goats although no significant difference was found between these two species. In the third phase specimen samples (Lymph nodes, Spleen, Nasal swabs) were collected by attending different out breaks in the selected districts, these samples were evaluated by RT-PCR. Sequencing and phylogentic analysis of the samples were performed. Prevalence of PPR virus detected by RT-PCR was 62.8 and 63.9% in sheep and goat, respectively. In present study difference between sheep and goat prevalence is non-significant. In the F gene phylogenetic relationship the sequence in study clustered with sequence pattern from Pak 09 with accession no. (FN996973.1), Bhutan 10 (FR667649.1) and Bangladesh 2000 (FR667556.1), branching pattern. In the present study maximum predilection site of the virus was found in lymph node (100%) followed by spleen (100%) and nasal swab (62.85%) from sheep. The goats of eastern Punjab districts showed maximum detection (100%) followed by southern Punjab district (88.88%). In the final phase of the study, antibody titre of sheep and goats were evaluated by using technique of indirect haemagglutination (IHA). Two vaccines were used in the trial containing Nigerian 75/1 strain used for commercial purpose vaccination in the country. A non-significant difference was present between two vaccine responses in present trial and both vaccines were equally effective. In conclusion the PPR prevalence ratio is increasing in sheep and goat population of Punjab. The F gene of PPRV can be used for the detection of PPR disease and lymph node is the prime organ for virus detection in sheep and goat.