Floods and heavy rains in Victoria have caused mosquito numbers to soar, prompting the state’s health authorities to issue an early warning.

The Department of Health said the weather had provided perfect breeding conditions for the insects, and as a result surveillance and control programs had been brought forward a month.

Seven flood-affected councils, including Mildura, Swan Hill, Gannawarra, Campaspe, Moira, Wodonga and Shepparton, have started spraying breeding sites, with experts predicting mosquitoes will be a serious problem in summer.

The health department said a full-time mosquito monitor was spraying parklands and areas with stagnant water in several council areas and the insects were being trapped to count their numbers.

Mosquitoes thrive in damp conditions and near bodies of water. Photo: Getty

It warned people to protect themselves from bites as mosquitoes can carry the Ross River and Barmah Forest viruses, which cause joint inflammation, pain and rashes.

In very rare cases, a mosquito can also carry the potentially deadly Murray Valley Encephalitis virus (MVE), that can cause the brain to swell.

The department said, however, the last human case of MVE was in 1974.

In Victoria last year there were 301 reported cases of Ross River virus and 11 cases of Barmah Forest.

Professor Charles Guest, Victoria’s chief health officer, said everyone should try to avoid being bitten.

“It’s important to look after small children and babies using mosquito repellents, mosquito nets, ensuring that those who can’t protect themselves are, as far as possible, protected against mosquito bites,” he said.

“If you have concerns about your health or otherwise of course talk to your doctor or call nurse on call which is 1300 606 024.”

Professor Guest said swarms of mosquitos were more common now than they had been in a dry summer.

“Mosquitos are thriving in the damp conditions and as it gets warmer there will be more of them,” he said.

The soaring mosquito population is already evident in Melbourne where one motorcycle rider said his helmet was covered in dead mosquitos in less than seven minutes as he was riding east of Edithvale.

He said at first he thought it was spitting rain when he heard the sound of the insects hitting the helmet.