In the year to date, there has been 175 cases in the Hunter New England region, up from 33 in 2016.

In the Peel Cluster, there has been 42 reports, compared to just seven last year.

NSW Health Environmental Health Branch director Ben Scalley said the mosquito-carried virus cases were higher than usual this year in inland parts of the state.

“Conditions are now prime for breeding along the coast, where we expect the risk to increase,” Dr Scalley said.

“It is possible that mosquitoes west of the mountains will be carrying the even more serious viruses such as Kunjin and Murray Valley encephalitis.

“Protect yourself by wearing clothing that covers your arms and legs and by applying repellent to exposed skin, particularly at dusk and dawn and when outdoors.”

Ross River and Barmah Forest virus infections can cause unpleasant symptoms including tiredness, rash, fever and sore and swollen joints.