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Japanese encephalitis virus and dengue virus found in Townsville

Two people with different serious mosquito-borne viruses are being treated in Townsville. DETAILS.

Dengue, Japanese encephalitis viruses detected in NQ

Two rare mosquito-borne viruses have been detected in Townsville, with the first locally acquired case of dengue virus since 2020 being treated.

Townsville Public Health Unit director Dr Steven Donohue has revealed a resident was also being treated at Townsville University Hospital for Japanese encephalitis virus (JEV), however experts believe it was caught outside of the region.

“Since the Eliminate Dengue project started almost 15 years ago … the disease has been almost non-existent,” he said.

“What we think is happening here is not 100 per cent of all our local dengue mosquitoes are covered with this bacteria.

“If we get a tourist come in with dengue virus in their blood, it could infect one of those mosquitoes, and through just bad luck it looks like it has infected one or possibly a couple of people in the North Ward.

“This is an elderly man, he’s recovering in the Townsville hospital.”

Every time a case is detected, the Public Health Unit investigate the source.

“Because this is now more than a week down the track, we are making sure there are no longer infective mosquitoes in that area in case there are some carrying the virus,” he said.

“We will go there and work with the locals to kill mosquitoes with their permission, that would involve exterior spraying and interior spraying.”

The unit often collects mosquitoes to study in affected areas.

Dr Donohue said it was just “bad luck” and said patients feel like they have “been run over by a truck”. He added that the patient should be home soon.

In 2020, two people were treated for dengue virus, and were the first to be treated for the disease since 2016. The two patients lived in Stuart and Condon.

The Aedes aegypti mosquito is originally from Africa but is now found in tropical regions across more than 120 countries. Picture: CSIRO
The Aedes aegypti mosquito is originally from Africa but is now found in tropical regions across more than 120 countries. Picture: CSIRO

Wolbachia bacteria was first introduced into Aedes aegypti mosquitoes in 2011 as part of a bid to eradicate dengue virus.

Since then, the disease has been almost non-existent.

“Dengue is a massive problem throughout the tropical world, there are hundreds of millions of cases every year,” Dr Donohue said.

“Most of the cases are pretty mild or even asymptomatic, but a big percentage of them case that quite severe disease with high virus, headaches, joint pains, rash, nausea, even pneumonia.

“In severe cases, particularly if this is your second or third infection with a different type of dengue strain, you can get shock, bleeding, and people can die.”

He added that there were not enough dengue-carrying mosquitoes in Townsville for an outbreak to “get off the ground”.

Mosquito bites on the arm
Mosquito bites on the arm

“Both cases (of dengue and JEV) are breakthrough cases and are not outbreaks,” Dr Donohue said.

“The cases are not linked. The chances of further cases in the community are low.”

JEV is a rare virus which came to Australia a few years ago and is related to Murray Valley and Kunjun viruses. It is spread through bush mosquitoes and leads to brain swelling with a sudden headache, high virus and disorientation.

“This is the first case of JEV that we have seen in Townsville and it is very unlikely the patient got the disease here as they had been holidaying in southern Queensland where the virus has been present,” Dr Donohue said.

The middle-aged man is in a stable condition.

Dr Donohue said that there have been a handful of cases of JEV in Victoria, NSW and previously in Queensland.

“He was camping during his exposure period down near Goondiwindi where we know that there’s virus activity, we’ve detected it in mosquitoes there,” he said.

“This is almost certainly a case imported into Townsville, that’s why we’re saying the risk is very low and we do not have an outbreak.”

A mosquito.
A mosquito.

Dr Donohue said before the Eliminate Dengue project, there would have been “dozens of cases every year”.

“Cairns was having occasional outbreaks of hundreds of dengue (cases) in the past before the Wolbachia coverage,” he said.

“Japanese encephalitis and dengue are short term illnesses, your body will clear the virus within a couple of weeks but it can do some damage,”

“There is a vaccine being used for people at high risk of Japanese encephalitis, people who work in piggeries, geographical areas where there’s a lot of known virus activity and laboratory and field workers who work with mosquitoes and those viruses.”

Dr Donohue said this was a reminder that mosquito-borne viruses were out there, with the most common Ross River virus and Barmah Forest virus.

He said people could help eliminate exposure to mosquito bites in and around the home.

“Mosquitoes breed in small quantities of water which can be found in items like tyres, buckets, toys or pot plant bases,” he said.

“Tip out the water and limit the chances of them breeding in your own backyard.”

He said to wear long, loose, light coloured clothing and cover your feed when outside or in the bush.

Dr Donohue said to use insect repellent with DEET or picaridin, as well as electric zappers or mosquito coils.

caitlan.charles@news.com.au

Originally published as Japanese encephalitis virus and dengue virus found in Townsville

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Original URL: https://www.thechronicle.com.au/news/townsville/japanese-encephalitis-virus-and-dengue-fever-found-in-townsville/news-story/63c6941f68ab3a9cd9457416cba5effc