People are being warned not to handle injured or heat-stressed bats because their scratches and bites may pass on a deadly virus to humans.

NSW Health's warning about the Lyssavirus follows reports that large numbers of bats have died in the recent hot weather and bushfires.

It's concerned that people may pick up and attempt to rescue bats that are injured, heat-stressed or tangled in fence wire.

The department says there have been two reports of bat bites in the Nowra area where bushfires have been burning.

Dr Jeremy McAnulty, Director of Health Protection NSW, said on Friday that Lyssavirus was rare and only transmitted through bites and scratches.

"Many people are bitten every year and people should assume that all bats and flying foxes are infectious, regardless of whether the animal looks sick or not."

Dr McAnulty said a Lyssavirus infection could result in a rabies-like illness which if not treated may be fatal.

People bitten or scratched by bats should thoroughly clean the wound, apply antiseptic and seek urgent medical advice, he said.

People should also call the Emergency Animal Disease Hotline on 1800 675 888 for advice.

Dr McAnulty said only people who have been fully vaccinated against rabies, use protective equipment and have been trained in bat handling should handle bats.