A virus that killed several Indian tigers in the past is back and has India scrambling to protect its dwindling tiger population after several big cats have been discovered to carry a virus common among canine but deadly to other carnivores, reported experts.

According to Rajesh Gopal of the National Tiger Conservation Authority, canine distemper virus left at least four tigers dead and several other animals throughout northern and eastern areas of India in 2013.

The discovery is bad news for wild tigers, already endangered due to illegal poaching and reducing habitat as India continues its breakneck developmental efforts to accommodate the staggering growth of its population. The economic development and population growth has resulted to an increased number of people and more dogs coming in contact with animals in the wild.

India has resolved to test every tiger carcass found for the deadly virus, Gopal reported, while authorities are also planning a massive vaccination campaign for dogs against canine distemper.

"We cannot vaccinate every dog, of course. But even 50 percent of dogs in the zones around sanctuaries would help," the official shared. He did not disclose details of the government's plans regarding the project. There is currently no known vaccine for big cats.

The cases found in various locations in India, however, suggests that canine distemper could have already reached the wild, officials explained, though they agree that further investigation is required.

"These are very disturbing finds," explained Indian Veterinary Research Institute's head scientist, Dr. A.K. Sharma. "The cases were quite distant from each other, and the latest was an area where there are no dogs. So it appears the virus is spreading."

The institute is currently heading the testing process for canine distemper.

After two cubs tested positive for the virus in a Bihar zoo in 2013, Dr. Sharma and his colleagues have discovered at least four more cases including a zoo lion in Darjeeling, a wild tiger in West Bengal, a red panda in the northeast state of Manipur and another wild tiger in the Dudhwa Tiger reserve located in Uttar Pradesh.