What mosquito-borne disease is hitting the US and how deadly is it?

The US is currently experiencing a surge in eastern equine encephalitis, a rare but extremely dangerous virus spread by mosquitoes.

In New Hampshire, one person has already died from the disease, while neighboring Massachusetts has imposed a partial curfew, closing parks and other public outdoor spaces between sunset and sunrise to reduce the risk of people being bitten by mosquitoes that carry the virus.

Here you will find everything you need to know about EEE.

What is Eastern Equine Encephalitis Virus?

Eastern equine encephalitis, better known as EEE or ‘Triple E’, is a virus that is transmitted to humans through the bite of an infected mosquito. The virus causes encephalitis and affects the functionality of the brain and nervous system.

EEE occurs naturally in certain birds and rodents in the United States – especially on the East Coast – and has also been found in Central and Latin America, Canada, and the Caribbean.

Mosquitoes become carriers of EEE after feeding on an infected bird or rodent. These mosquitoes can then transmit the virus to humans and other animals. It cannot be spread directly between humans, and neither humans nor horses circulate enough of the virus in their bodies to pass it back to mosquitoes.

The virus is most commonly found near freshwater marshes and lakes, where mosquitoes thrive. People who work outdoors in these areas are most at risk.

EEE was first identified in horses in the 1830s. Hence the name. EEE can affect both horses and humans with acute symptoms.

According to the Centers for Disease Control and Prevention (CDC), an average of 11 human cases of EEE are recorded each year in the US.

The largest recorded outbreak occurred in 2019, with 38 cases and 12 deaths in Massachusetts.

What are the symptoms?

According to the CDC, EEE has a very high mortality rate of at least 30 percent. This means that approximately one in three people who contract the disease will die.

Some people may be infected without showing symptoms, but due to a lack of surveillance and testing, data on this is limited.

Those most at risk are people over 60 and children under five, but the virus can affect people of all ages. Symptoms often begin with fever, chills, body aches, vomiting, diarrhea, and fatigue.

The infection can then develop into encephalitis (an inflammation of the brain) and meningitis (an inflammation of the membranes surrounding the brain and spinal cord).

Survivors of EEE may be left with lifelong mental and physical disabilities due to damage to the brain and central nervous system. Effects can range from behavioral changes and memory loss to paralysis and permanent brain damage.

Where have cases been reported?