Nobody likes mosquitoes — not only are they stinging pests, but they also carry a host of diseases.
And the recent deluge of rain has provided them perfect breeding conditions, with heavy rainfall triggering dormant eggs to hatch and swarm flooded regions.
A “very high” number of mosquitoes are concentrated in Sydney’s western suburbs, including Parramatta, and in the Georges River at Bankstown and Illawong, according to a recent report, cited by AAP.
Large numbers have also been recorded on the coast at Port Macquarie and on the Queensland border, but those living in inland areas can breath a sigh of relief because populations are believed to be quite low.
Speaking to AAP, medical entomologist Cameron Webb of NSW Health Pathology, said Australia is home to dozens of different kinds of mosquitoes.
The most concerning are the aedes vigilax and culex annulisrostris mosquitoes which can carry diseases such as Ross River Virus.
Only female mosquitoes bite as they need the nutrients in blood for their larvae. But if one bites a wallaby or kangaroo infected with the virus, it can transfer the illness to its next human victim.
Ross River isn’t fatal but it can cause a fever, severe joint pain, swelling and fatigue lasting for weeks to months.
Mosquitoes also carry several other diseases — some more deadly than others — like Murray Valley Encephalitis or Kunjin Virus, which is a rare but potentially fatal disease.
This can happen in northern parts of Queensland, the Northern Territory and Western Australia, particularly during the wet season.
The virus is transmitted by mosquitoes from water birds such as herons.
Dengue fever — more common in Asian nations — is also possible in far north Queensland.
Symptoms of Dengue fever include a sudden high fever, severe headaches, pain behind the eyes and fatigue.
Thankfully, Dr Webb said an increase in mosquito numbers doesn’t always correlate to a climb in infections, but he warned climate change could also boost numbers.
“It’s difficult to predict, but on balance more mosquitoes are likely, as there’s an extension of the season into spring and into autumn,” he told AAP.
And wiping them out isn’t easy. Even when bushfires destroyed one of Dr Webb’s mosquito monitoring stations last month, he returned a few days later to find that the mosquitoes had returned.
“They moved back in very quickly so we know the eggs must have survived the fires,” he explained.
By lying dormant in the soil, it was likely they were protected from the intense heat.
“They’re pretty hardy, they survive through winters and drought as eggs, and as soon as those areas flood, they hatch.”
But bushfires have wiped out most of the mosquitoes’ food sources, which could have long-term effects.
“It could be that as the surviving animals move nearer to people where there’s food, the mosquitoes may follow,” he said.
Dr Webb added that this could lead to more opportunities for diseases to be transferred.
“We just don’t know, we’ve never had an extreme event like this before,” he said.