Explainer: What is Murray Valley Encephalitis Virus?

Explainer: What is Murray Valley Encephalitis Virus?

Western Australian health authorities recently issued warnings about Murray Valley encephalitis, a serious disease that can spread by the bite of an infected mosquito and cause inflammation of the brain.

Thankfully, no human cases have been reported this wet season. The virus that causes the disease was detected in chickens in the Kimberley region. These “sentinel chickens” act as an early warning system for potential disease outbreaks.

What is Murray Valley encephalitis virus?

Murray Valley encephalitis virus is named after the Murray Valley in southeastern Australia. The virus was first isolated from patients who died from encephalitis during an outbreak there in 1951.

The virus is a member of the Flavivirus family and is closely related to Japanese encephalitis virus, a major cause of encephalitis in Asia.

Murray Valley encephalitis virus is found in northern Australia circulating between mosquitoes, especially Culex annulirostris, and water birds. Occasionally the virus spreads to southern regions, as mosquitoes come into contact with infected birds that have migrated from northern regions.

How serious is the illness?

After being transmitted by an infected mosquito, the virus incubates for around two weeks.

Most people infected don’t develop symptoms. But, if you’re unlucky, you could develop symptoms ranging from fever and headache to paralysis, encephalitis and coma.

Around 40% of people who develop symptoms won’t fully recover and about 25% die. Generally, one ...

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