As summer approaches and warmer weather approaches, Dr Heather Flores, director of research at the Institute of Vector-borne Diseases at Monash University, said floodwaters and torrential rain in Victoria would revitalize mosquito eggs until they hatch after a dormant winter.
Flores warned of the possibility of clouds of blood-sucking flying insects.
A flooded road in Echuca.attributed to him:Steve Huntley / Riverview Herald
Flores, who oversees the institute, which brings together some of the country’s top scientists to tackle the growing risk of infection transmitted by mosquito bites, said.
Professor Ari Hoffman, head of environmental genetics at the University of Melbourne, said the expected onslaught of torrential rain and stormy conditions in the warmer months would feed the mosquitoes.
While mosquitoes are a problem every Australian summer, the emergence of traumatic Japanese encephalitis has changed the nature of mosquito-borne diseases. The outbreak in pigs led to dozens of infections and five deaths earlier this year.
Flores said Victorians are at increased risk of Japanese encephalitis because the disease can spread among mosquitoes, birds and pigs as well as humans.
A woman carries her luggage through flood waters in South Shepparton.attributed to him:Jason South
“There are a lot of potential hosts that could basically keep this virus circulating in the population and potentially remain unknown to us,” she said.
Historically extreme weather has contributed to an increase in the number of mosquito-borne viruses, most notably an outbreak of encephalitis virus in the Murray Valley in the 1970s. Above-average rainfall also led to Ross River virus outbreaks in northern New South Wales and southeast Queensland in 2014-2015.
The floods in Victoria in 2017 were also closely associated with the largest outbreak of Ross River virus, causing a nearly fivefold increase in the number of infections.
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Record-breaking rainfall and warm temperatures are also thought to have been important factors in JE gaining a foothold in Australia.
The virus, which first arrived in Australia earlier this year, has been genetically linked to fatal cases on the Tiwi Islands and Papua New Guinea. Scientists believe it was carried to the Australian mainland by migratory waterfowl – or mosquitoes blown up by monsoon rains.
Globally, Japanese encephalitis is common among waterfowl, pigs, and humans, and kills about 17,000 people annually. But before last summer, it had never been discovered south of Cape York.
Experts say the deadly disease came to Australia due to a warming climate, and is now here to stay, as vaccines will soon be distributed to people living in high-risk areas, including the Murray River.
Less than 1 percent of those infected develop clinical disease, but among those infected, the virus can be fatal as it travels to the spinal cord and brain.
The massive summer rains in La Nina also provided a breeding ground for Culex mosquitoes, the species highly suspected of being the main vector of Japanese encephalitis.
It’s almost impossible to predict how many mosquitoes Victoria expects this summer, Flores said, because the population boom depends on rainfall and the amount of standing water left. Adult mosquitoes generally live only about three weeks.
The Victorian Department of Health warned on Monday that mosquito numbers were on the rise, and asked people in flooded areas to remove standing water from around their homes to stop breeding.
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People in flooded areas are being urged to wear long, loose-fitting clothing if possible, amid warnings that mosquitoes may bite through tight clothing. Heavy-duty mosquito repellents and the use of nets or insect screens are also recommended.
MacKenzie said Japanese encephalitis has an additional threat of an infected person traveling across the country, carrying the virus with them, and inadvertently causing an outbreak when bitten by another mosquito, which could then transmit the virus to humans or other animals.
Symptoms of Japanese encephalitis include fever, headache, muscle aches, and fatigue. Some people may also develop a rash. While the virus is not considered fatal, in rare cases a person can have symptoms for more than a year.
“It’s very important for people to be vigilant,” Hoffman said. “That’s really the key here – do everything you can to reduce mosquito breeding sites.”
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Originally published at Melbourne News Vine
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