How to protect yourself from Sydney's new disease worry

As if the coronavirus weren't enough to worry about, there's a new modern plague on the horizon.

After a rainy few weeks and a spell of warm weather, Sydney's mosquito population has exploded, and the spread of Ross River virus along with it.

The city is in the middle of the biggest spike of cases in almost three decades, prompting a warning from medical experts.

Dr Cameron Webb from NSW Health Pathology speaks to 9News tonight about how to protect yourself from infection.

"We've seen an explosion in mosquito populations," he said.

Conditions are especially bad on the Northern Beaches, around Georges River, Parramatta River and the Hawkesbury. Just last month, 434 cases of the virus were recorded in NSW – more than five times the amount documented last April, making it the state's highest number of infections in almost 30 years. Symptoms include a rash, fever, aching joints and fatigue.

"It's quite clear the government needs to increase their spraying program to get this virus under control," Shadow Health Minister Ryan Park said.

To avoid being bitten, the advice is to roll down your sleeves and ramp up the repellent.

"If people are outdoors at dawn or at dusk when mosquitoes are most active, they should put on a tropical insect repellent," Dr Webb said.