Field and molecular epidemiology of Peste des Petits Ruminants in Pakistan

Peste des Petits Ruminants (PPR) is a highly fatal and economically devastating disease of sheep and goats. Present study was designed to have an insight into the epidemiology of PPR under field conditions in the country using molecular tools. A total of eighty-four (n = 84) PPR outbreaks were investigated during the study (2010 to 2013). The highest number of outbreaks was reported from Punjab province (n = 38) followed by Sindh (n = 21) and Khyber Pakhtunkhwa (KPK, n = 10). In 48 out of 84 outbreaks, disease occurred in goats only while 18 outbreaks affected sheep only and the remaining occurred in mixed herds. A total of 6221 animals were affected in these outbreaks. Sheep were less severely affected in comparison with goats. The morbidity, mortality and case fatality rate were 26.79%, 10.83% and 40.41% in sheep in comparison with 34.90%, 16.34% and 46.82% in goats, respectively. Overall, disease affected all three age groups of sheep and goats but the younger animals were more severely affected with a morbidity rate of 37.19%. The mortality and case fatality rates were also higher in young which were 46.86% and 17.39%, respectively. Yearly data of outbreaks was suggestive that a cyclic as well as seasonal pattern of disease occurred. The results of the phylogenetic tree indicated that all Pakistani PPRV strains, regardless of the gene used either F or N, clustered in lineage IV which is the most prominent and prevalent lineage of Asia. The distribution of Pakistani strains of PPRV was more dispersed as the isolate collected from Taxilla was clustered slightly distinct compared to rest of the isolates collected from Pakistan. Our findings are indicative of PPR endemic state of the country.