The warning comes after the first Ross River virus case of the season was detected in Griffith on Monday.

According to Murrumbidgee Local Health District mosquito surveillance senior environmental health officer Tony Burns, it is better to be safe than sorry this Easter.

"Ross River is there, and we do see Murray Valley encephalitis virus that came back last year after being away for 12 or so years," he said.

The Murray Valley encephalitis virus is one that could have posed a problem had the weather conditions swayed towards being wet over the weekend.

Mr Burns said the re-emergence of the virus is likely due to a combination of things, including wetter weather conditions across the region.

It, as well as Japanese encephalitis virus, can be serious if contracted by humans and both viruses are definitely in the region.

"Japanese encephalitis virus has been around as well," Mr Burns said.

"Encephalitis viruses can be very serious."

While Mr Burns said they have had two cases of Japanese encephalitis in the Riverina this season, they have not been human cases.

As autumn continues, Mr Burns said it was important residents didn't assume mosquitoes would be gone along with summer.

Mr Burns said mosquitoes would indeed be out in numbers for several weeks to come, and there was no spotting an infected mosquito, so the best bet was to be prepared.

"People need to know these viruses are out there in the right circumstances, the right conditions, they can re-emerge," he said.

"Mosquito numbers have dropped off a little bit with summer being over. the ski season has finished just in the last few days from the trapping and the sentinel surveillance that we do, but it's still important.

"There are mosquitoes around, they will be around over Easter and the weather's going to be good, so people will be outside, so we want them to take home that message of using repellent, covering up, using light, long loose fitting clothing and just taking appropriate precautions."

Mr Burns said hot spots would be in the region's west where there was water lying around.

"Out around Leeton and Griffith, there's always a lot of water there because of the farming, so their numbers are high and they will remain high for a little while," he said.

"People going to those areas should definitely take precautions."

Mr Burns said there were more than 400 species of mosquito and the Riverina typically saw six of them.

Viruses can cause unpleasant symptoms including tiredness, a rash, fever, and sore and swollen joints, and more serious infections can result in long-term disability and even death.