What is Eastern Encephalomyelitis? Two Mosquito Researchers Explain What’s Behind the Latest Outbreaks

Health authorities in the United States are issuing warnings and closing public parks due to a occasional but potentially deadly mosquito-borne disease.

This week, a resident of the US state of Fresh Hampshire he died after being hospitalized for Eastern encephalomyelitis. Cases have also been detected in other states.

But what is eastern equine encephalitis? How does it spread? What do horses, as the name suggests, have to do with it? And is it a problem for Australia?

What is Eastern Encephalomyelitis?

Eastern encephalomyelitis It is caused by a virus that is usually found only in parts of eastern America, Central America Down Canada.

Eastern encephalomyelitis virus causes neurological disease, specifically encephalitis (inflammation and swelling of the brain), and is transmitted to humans by mosquito bite. Symptoms can be serious and potentially fatal.

But most people bitten by a mosquito carrying the virus will not have symptoms. Those who do develop the disease have symptoms that include headache, stiff neck, disorientation, seizures, and coma.

About one third Patients with severe symptoms die, and many of those who survive suffer from chronic neurological problems.

It’s not just humans who are at risk from the virus. Horses are too susceptible and, like humans, they can also contract deadly encephalitis when bitten by an infected mosquito.

The virus was discovered after the outbreak of the epidemic fatal disease in horses in the Fresh England region of the USA in 1831, hence the reference to a horse disease in the name.

Wild, farmed and captive birds can also be infected with the virus and some species develop disease. In fact, birds are key to how the virus spreads.

How is Eastern encephalomyelitis virus spread?

Birds – especially passerinea group that includes robins, starlings, thrushes and blue jays – are the main hosts of the virus.

These birds produce high enough levels of the virus that allow it to infect biting mosquitoes and maintain what is called the “transmission cycle.”

Mosquitoes that feed on birds in forested wetlands, especially Melanour slideallow the virus to circulate among birds. But this mosquito rarely bites humans, so it is not as essential for human disease outbreaks.

Mosquitoes feed on both birds and mammals which transmit the virus to humans and horses. These include Capricorns, Coquilettydia AND Culex mosquitoes. But once infected, humans and horses do not spread the virus. That’s because they do not produce high enough levels of the virus to infect mosquitoes.

How can we limit the spread?

There are no specific treatments for Eastern encephalomyelitis virus infection, or any licensed vaccines for utilize in humans. There is a vaccine registered for veterinary use to prevent viral infections in horses.

The main strategies to limit human exposure to the virus are personal protective equipment and mosquito control.

Epidemics can have a significant impact on communities, not only because of the disease itself, but also because of the measures implemented to limit its transmission.

Recent outbreaks have led to the cancellation of outdoor events. Concerns have also been raised about the widespread utilize of aerial “fogging” to kill mosquitoes, as the chemicals commonly used are not specific to mosquitoes and may pose a risk to other insects.

Some cities have closed park areas evening and asked residents not to leave their homes at night.

Why did the epidemic break out now?

The virus circulates throughout the year in tropical regions. like FloridaIn the northeastern part of the USA, the virus has more sporadic activityHere it is usually introduced by migratory birds and is busy during the warmer months when the mosquito population is high.

This virus has been known for many decades and has had many outbreaks in North America. One of the last major outbreaks It was in 2019 in several northeastern states of the USA, when 38 human cases (including 12 deaths).

There is evidence that the virus is spreading to fresh regions of North America. However, given the sporadic nature of the epidemic, it is hard to predict when it will occur.

Many factors could influence future disease outbreaks and the spread of the virus to fresh regions, including climate, environmental factors, mosquito and wildlife activity, and, importantly, humans.

As human contact with mosquitoes that can carry the virus from infected birds increases, the risk to public health increases.

It is possible that human activity near mosquito and bird habitats, including urban encroachment on forested wetlands, increases the risk.

That is why it is so essential for health services to monitor mosquito and virus activity. provide early warning risk of human disease.

Is there a risk to Australia?

There is no evidence that eastern encephalomyelitis virus occurs in Australia and there is no immediate risk of its introduction into this country.

One sec Slide mosquitoes are located in AustraliaTheir role in local viral epidemics in humans and animals is not well understood.

But dozens of different mosquitoes are involved in this process. spread of alphaviruses in Australia. This group includes the eastern encephalomyelitis viruses, as well as those that occur in Australia, namely Ross River AND Barmah Forest viruses.

It can be assumed that some of these mosquitoes can transmit the virus, but this has not yet been tested in laboratory experiments.

There is very little information on how local passerine birds may play a role in establishing virus transmission cycles in Australia. There is also no information on whether native Australian vertebrates, such as marsupials, would respond to infection.

Considering all available evidence, the risk of the virus spreading to Australia and causing an epidemic is most likely very low.

Are travellers at risk?

The risk of being bitten by a mosquito carrying eastern encephalomyelitis virus is extremely low. However, anyone visiting eastern regions of North America, including the United States and Canada, where the virus may be present, should take precautions to avoid being bitten by mosquitoes.

Follow guidance from local health authorities. And take steps to avoid areas (especially wooded wetlands) and times when mosquitoes are busy (usually at dawn and dusk). Wear loose clothing with long sleeves and utilize repellents containing diethyltoluamide (commonly known as DEET), picaridin, or oil of lemon eucalyptus.

These precautions will also protect you from contracting other mosquito-borne viruses you might encounter there, such as: West Nile Virus.