Mosquitoes belonging to the genus Culex are believed to play the most important role in the transmission of Japanese encephalitis virus. Credit: Cameron Webb/New South Wales Health Pathology

Mosquitoes are a problem every summer. But the recent arrival of the mosquito-borne Japanese encephalitis virus in eastern Australia is causing more serious problems.

There is hundreds of different species of mosquitoes in Australia, but only about a dozen pose a threat to public health. The activity of these mosquitoes varies from season to season with differences in rainfall and temperature.

Climate change and extreme wet weather can increase the number of mosquitoes and bring additional threats.

So how can we reduce our risk of contracting mosquito-borne diseases, including Japanese encephalitis?

First, some ointment basics

Mosquitoes need stagnant water to complete their life cycle. Immature mosquitoes hatch from eggs and complete their development underwater until they pupate before emerging as adult mosquitoes.

Female mosquitoes need blood before laying eggs. They seek blood from a wide variety of animals and, in addition to sucking blood, can pick up the virus. This virus can then be passed on to another animal or human when they need another blood supply.

Mozzies make you sick by injecting a cocktail of saliva and virus when they bite you. “Mozzie spit” can leave you with an itchy, red bump as well as a dose of a potentially fatal disease.

What diseases can mosquitoes carry?

Australia has always struggled with mosquito-borne diseases. Ross River virus is contagious thousands of people every year. Seems like extreme weather events an increase in the number of cases around our cities and growing coastal communities.

Murray Valley Encephalitis Virus is incredibly rare but can be fatal. There were significant outbreaks closely related to flooding throughout the Murray-Darling Basin region.

Mosquito-borne diseases are not only a threat to humans. Horses can get hurt severe symptoms after infection with Ross river virus or Kunjin virus.

There are also concerns about Ephemeral bovine fever and skin tumor in cattle.

Even in our backyard, our dogs can get hurt parasites spread by mosquito bites.

What about the Japanese encephalitis virus?

The discovery of the mosquito-borne Japanese encephalitis virus changed the landscape of mosquito-borne diseases in Australia last summer.

The disease may be mild, with common symptoms of fever, joint pain, and rash. In severe cases, people also experience headaches, neck stiffness, confusion, seizures, and sometimes coma and death. Less than 1% of those infected will develop a severe brain infection, encephalitis, which can be fatal.

Japanese encephalitis virus causes serious health problems Southeast Asia and the Western Pacific. The virus circulates between mosquitoes and waterfowl but pigs can be hosts too.

The virus was first detected in v commercial pig farms where reproductive losses were observed and in March Australia declared it an “infectious disease of national concern”.

The virus has been detected in humans, pigs (both in commercial pig farms and wild populations) and mosquitoes in South Australia, Victoria, New South Wales, Queensland and the Northern Territory. Were 40 cases of human diseaseincluding six deaths.

A a recent study of five regional communities in southern New South Wales suggests nearly 9% of population population was exposed to the virus last summer.

What can happen this summer?

Another wet summer awaits us thanks to a the third season in a row under the influence of La Niña. The flood is mine already started.

More rain doesn’t just mean more mosquitoes: it also means better breeding conditions for waterfowl. More water, more birds and more mosquitoes sets the stage for potentially more Japanese encephalitis and other mosquito-borne diseases.

Mosquito species are of greatest concern Culex annulirostris. This mosquito is most likely the cause of transmission of the virus among animals as well distribution to the population.

This species is closely associated with freshwater habitats. With severe flooding in many regions, there will be plenty of suitable habitat over the coming summer.

So, how can we reduce the risk?

Meanwhile, authorities are looking for ways to control the mosquito population, such as spraying insecticides especially around piggeries and other high-risk locations, insecticides alone will not eliminate the risk of Japanese encephalitis virus infection this season. Other strategies are required.

A a safe and effective vaccine is available and authorities develop strategies to provide for “at-risk” communities and individuals access to it.

But worldwide, there simply isn’t enough vaccine to vaccinate everyone at risk in Australia.

Surveillance will provide early warning of increased risks. There will be power track and test mosquito populations for the presence of the virus, as well as various animal surveillance networks. If detected, authorities can respond strategically through increased surveillance, control, or education programs.

Many of the ways we reduce mosquito bites during summer months to allow us to enjoy our time outdoors, be it in the bush backyard, also protect against mosquitoes that carry these viruses.

Wide sleeves with long sleeves, long pants, and closed-toe shoes will create a barrier to mosquito bites.

Application of topical insect repellents, especially formulations containing diethyltoluamide, picaridin or oil of lemon eucalyptus, will ensure safe and effective long-lasting protection against mosquito bites.

Preventing mosquito bites is the best way to protect yourself and your family from mosquito-borne diseases.


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Citation: Recent arrival of mosquito-borne Japanese encephalitis virus in eastern Australia (2022, October 7) Retrieved October 7, 2022, from https://medicalxpress.com/news/2022-10-mosquito-borne-japanese-encephalitis -virus-eastern .html

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