A bat carrying the deadly lyssavirus bit a Hawthorn man trying to come to its aid last month, prompting authorities to put out a public health warning.

The man was bitten in April when he went to help the injured bat. Tests revealed the bat was carrying lyssavirus, a disease closely related to rabies which is 100 per cent fatal if not treated.

A flying fox at Healesville Wildlife Sanctuary is checked over for lyssavirus. Credit:Mark Wilson

An immediate two-week course of rabies vaccine stopped the man from falling sick. But it prompted Victoria’s deputy chief health officer Dr Brett Sutton to warn people that they should avoid touching bats.

“Australian bat lyssavirus is a rare but fatal disease which may be transmitted from bats to humans. Domestic pets may also be at risk,” Dr Sutton said in a warning issued on Thursday.