Mozzies may be carrying Japanese encephalitis this summer. Here’s what you need to know if you spend time outdoors

According to reports, he is a Victorian man in critical condition in hospital after contracting Japanese encephalitis from a mosquito bite.

This message appears after both cases Victoria AND New South Wales has issued public health alerts in recent weeks warning about the virus.

So what is Japanese encephalitis and how can you protect yourself and your family if you live, work or vacation in mosquito-prone areas this summer?

Mosquito-borne diseases in Australia

Compared to other parts of the world, Australia has traditionally had a very low risk of potentially life-threatening mosquito-borne diseases.

There is no widespread dengue, yellow fever or malaria. But there are still many viruses out there local mosquitoes may spread.

There are approximately 5,000 cases of mosquito-borne disease reported in Australia each year. The immense majority of them are due to Ross River virus. The disease caused by this virus is not fatalalthough it can be seriously debilitating.

A disease caused by two other pathogens, Japanese encephalitis virus i Murray Valley Encephalitis virus, are much rarer but potentially deadly.

The symptoms of human diseases caused by these two viruses are similar.

Most people infected show no symptoms. In subtle cases, fever, headache and vomiting may occur. In more stern cases, stiff neck, confusion, drowsiness and seizures may occur. Stern disease can cause lifelong neurological complications, and in some cases the disease is life-threatening.

There is no specific treatment for any of these diseases, although there is a vaccine Japanese encephalitis which may be appropriate for some high-risk people (more on this later).

Impact of weather patterns

Murray Valley encephalitis virus has been known in Australia for many decades. Following a significant outbreak in the Murray Darling Basin in 1974, overall disease activity increased limited to northern Australia.

Outbreaks in southeastern Australia often accompany flooding caused by La Niña weather patterns. Floods create perfect conditions for mosquitoes as well water birds which are the breeding ground for the virus.

Japanese encephalitis virus it is closely related to Murray Valley encephalitis virus. Mosquitoes Catch both viruses by biting waterfowl. However, the Japanese encephalitis virus has only recently become common in Australia.

After hefty rains from La Niña in 2020, this is a requirement lasted for three yearsThe Murray Valley Encephalitis virus is back and Japanese encephalitis virus arrived for the first time.

The Japanese encephalitis virus was first discovered in southeastern Australia summer 2021–22and a sharp increase in the population of mosquitoes and water birds that followed the flood contributed to its spread.

It was already in the area 80 cases of illness caused by these two viruses combined in the last four years. This includes seven deaths from Japanese encephalitis By Queensland, New South Wales, South Australia and Victoria.

Additional encephalitis deaths have been reported in the Murray Valley in recent years – two per person Western Australia and Northern Territory.

Summer 2023-24 hot and dry summer conditions have returnedthe number of mosquitoes decreased, and a number of cases the number of diseases caused by Japanese encephalitis virus and Murray Valley encephalitis has decreased.

Now Both viruses appear to have made a comeback. So what’s going on?

What’s different this summer?

This summer, the Japanese encephalitis virus was detected in the country mosquitoes and wild pigs in Novel South Wales. The virus was also detected in environmental supervision in northern Victoria and we know at least one person has been touched There.

Meanwhile, Murray Valley encephalitis virus has been detected in flocks of sentinel chickens health authorities to investigate the increased risk of mosquito-borne diseases – v New South Wales and in the Kimberley region Western Australia.

It is unusual to see the activity of these viruses when conditions are relatively dehydrated and mosquito numbers are relatively low.

Some areas of Australia may have experienced this floodbut many parts of the country were warm and dehydrated. This is bad news for mosquitoes.

There is no evidence that mosquito numbers are rising dramatically, as they did when La Niña brought flooding to the Murray-Darling Basin.

There is also no evidence of increased activity of waterbirds. In fact, their number has decreased in recent years.

So why are Japanese encephalitis virus and Murray Valley encephalitis virus becoming vigorous again when conditions seem less favorable?

Despite A’s predictions a rare return of La Niña in midsummerThere is still speculation about what this means for temperature and precipitation. We may not see flooding, but there will likely still be enough water for mosquitoes to exist.

In the case of the Japanese encephalitis virus, this may be it wild pigs play a more crucial role in its spread. We know the numbers are growing and in drier conditions perhaps mosquitoes and feral pigs, and other wild animalsthey gather together where they can find bodies of water.

After the unexpected emergence of the virus, it appears that the Japanese encephalitis virus is here to stay. However, how the virus interacts with local mosquitoes and wildlife under increasing, unpredictable climatic conditions requires further study.

How to reduce your risk this summer?

Public Health Alerts in Victoria AND New South Wales focus particularly on specific regions in northern Victoria and around Griffith and Narromine in Novel South Wales, where the virus has been detected.

If you live or work in an area at risk of Japanese encephalitis, seek advice from your local health authority to check if you are eligible for vaccination. Residents of certain local government areas in affected regions in both states are now eligible for the free vaccine.

However, there is no vaccine available for Murray Valley encephalitis and Ross River viruses.

Wherever you live, preventing mosquito bites is crucial. Utilize insect repellent outdoors, especially at dawn and dusk when mosquitoes are most vigorous, or at any time of day if you are in bush or wetlands where mosquito numbers may be high.

You can get more protection by also covering up with a long-sleeved shirt, long pants, and closed shoes.