Mosquito warning for Sydneysiders

Health authorities have warned people fishing and camping along Sydney's Georges River to cover up after mosquitoes carrying Ross River and Barmah Forest viruses were found in riverside suburbs.

NSW Health said the infected mosquitoes had been found in suburbs including Alfords Point, Illawong, Lugarno and Bankstown, while chickens infected with Kunjin virus had been found in Griffith and Forbes.

NSW Director of Communicable Diseases Vicky Sheppeard said the next few weeks will offer ideal breeding conditions for the mosquitoes which carry diseases such as Ross River virus, Barmah Forest virus, Kunjin virus and Murray Valley encephalitis virus.

"These infections can cause symptoms including tiredness, rash, fever and sore and swollen joints," Dr Sheppeard said on Friday.

"The symptoms usually resolve after several days but some people may experience these symptoms for weeks or even months.

"Infection with Kunjin or Murray Valley Encephalitis can also cause more severe effects such as encephalitis."

She said cases of mosquito-borne infections usually rose in autumn.