A VIRUS may be responsible for causing deformities in bats among the permanent colony at Cairns library in the city, a vet says.
The State Government and CSIRO are investigating why more than 100 newborn spectacled flying foxes with deformities such as cleft palates and twisted limbs have been found underneath trees near the library colony since the start of the year.
A James Cook University researcher studying the bats believed the cause may be related to chemical spraying or some other environmental stress.
Dallas McMillan, a veterinarian at the Cairns Vet Clinic, said some viral infections in animals could cause birth defects and abortion.
"When you get a big outbreak like that, often it is an infection or an environmental toxin," Dr McMillan said.
He suggested flying foxes eating poisonous weeds could also be the reason behind the deformities.
"If they have access to some weed that is poisonous - there are lots of weeds that can cause abnormalities in people and animals," Mr McMillan said.
Until the exact cause of the abnormalities was determined, Mr McMillan said it was important people did not touch or go near the flying foxes.
"These birth defects would often cause other health problems such as immunosuppression which makes bats more vulnerable to viral infections such as lyssa virus and hendra virus, which may increase the risk of infections in humans and other species," Mr McMillan said.
"Thus aborted, stillborn or deformed bats may pose a greater-than-normal risk of viral infection and be handled as possibly infectious."