Epidemiology of porcine reproductive and respiratory syndrome (PRRS) outbreak in India

Porcine reproductive and respiratory syndrome (PRRS) is recognized as an economically important swine disease worldwide. India has reported the first outbreak of PRRS in pig populations of Mizoram stateto OIE (World Organization for Animal Health) on 26^thJune, 2013. The outbreak was observed in an epizootic form in pig population of Mizoram and caused huge loss to the pig farmers. The disease was observed to affect all age groups including the pregnant sows with morbidity rate 44.01% - 80.29% and mortality rate 14.51% - 66.11%. However, the most severe acute respiratory disease with highest morbidity and mortality rate was recorded in preweaned piglets. Severe pathological lesions like hemorrhagic interstitial pneumonia, hemorrhagic lymphadenitis with lymphoid depletion, vasculitis and interstitial nephritis were observed in pigs of all age groups and reproductive failure in pregnant sows.Post outbreak serosurveillance revealed 28.26% seropositivity. Sequence and phylogenetic analysis of ORF-7 gene from field samples during the outbreak established the belonging of PRRSV in genotype II and revealed 99% sequence identity with the Chinese isolates characterized as highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV).