The pigs were believed to have been infected with the virus from pigs imported from Myanmar, veterinarians said.
Official sources confirmed the development but did not corroborate the death toll cited by the Pig Rearers' Association.
The sources said a meeting, convened by Aizawl District Deputy Commissioner Kannan Gopinathan and attended by officials of the state Animal Husbandry and Veterinary department and experts at the College of Veterinary Science and Animal Husbandry, decided that the Aizawl district administration would issue order prohibiting import of pigs and piglets from Myanmar.
Champhai District Veterinary Officer Dr Lalchungunga Pudaite told PTI over phone that though there is no vaccination and specific treatment for the PRRS, some of the infected pigs responded to antibiotics.