The health authorities in Malaysia say they may have wrongly identified the cause of the deaths of sixty-two people who were believed to have been killed by a virus transmitted to humans from infected pigs.

Scientists originally thought that all the deaths had been caused by the virus, Japanese encephalitus, which is transmitted from pigs by mosquitoes.

In response they killed eighty-thousand pigs in an attempt to contain the problem.

But now they have discovered that only eighteen of the victims died from that virus.

It's thought that a new, as yet unidentified virus, is responsible for the other deaths.