A Mosquito Virus is Killing People. Here's What You Need to Know.
Today is the last day of summer, but don't store away your bug spray quite yet. According to new reports, at least seven people have died from Eastern Equine Encephalitis, a rare but potentially fatal virus spread by mosquitoes.
Deaths have been reported in Connecticut and Massachusetts, and EEE has been reported by 27 people in six states—including 10 in Massachusetts and eight in Michigan. These numbers are incredibly high, considering that an average of just seven human cases of EEE are reported annually.
Here is everything you need to know about the latest arbovirus sweeping the east.
What is EEE?
According to the Centers for Disease Control, EEE is a rare cause of brain infections (encephalitis) spread to people by infected mosquitoes. The virus itself is often referred to as EEEV.
EEE is carried by birds. If a mosquito bites an infected bird, it can then transmit the virus to other animals or humans. The first E refers to the region where most cases of EEE are transmitted, the Eastern United States, more specifically in Atlantic or Gulf Coast states, per the Centers for Disease Control. The "equine" in the second E obviously refers to horses, as Matthew Mintz, MD, FACP, explains to Eat This, Not That! Health that they are more commonly infected with it. The third E, encephalitis, means infection of the brain.
Unlike Zika or influenza, which can be spread from person to person, EEE tends to stay in a specific geographic area where the infected mosquitos are located.
People over age 50 and under 15 seem to be at greatest risk for developing severe disease when infected with EEEV. Cases occur primarily from late spring until early fall, but in subtropical areas (such as the Gulf States) they can occur in winter.
The fatality rate is 30 percent, however, many survivors are left with ongoing neurological problems, including mild to severe brain damage. "When the brain is infected, it can swell and cause all sorts of problems including seizures and coma," Dr. Mintz explains.
Why is it such a bad year for EEE?
In the last couple of decades, EEE has become more widespread throughout the Northeast, according to Massachusetts state epidemiologist Catherine Brown. "Historically, Massachusetts has by far the most EEE activity. But Vermont, New Hampshire and Maine have only had EEE in the last 15 years or so. It had never been identified there before," Brown told Boston NPR station Wbur. "It's easy to say this could be a potential impact of climate change."
She explains that EEE outbreaks are usually triggered by a combination of two things: a new strain of the virus being introduced to the region from Florida and wetter-than-usual conditions over the last year. These two combined factors could be responsible for the surge in cases reported this year.
"Having a new strain of the virus from Florida tends to kick off a new [EEE] cycle. I can't prove it yet, but I anticipate that we are going to discover this is a newly introduced viral strain," she says. "And there was a lot of rain last fall and this spring. That means you will have larger mosquito populations."
"Most cases occur in July through September," Tom Skinner of the CDC tells Eat This, Not That! Health. "The virus circulates between mosquitoes and birds in freshwater hardwood swamps. It can then be transmitted to humans and horses, which are dead-end hosts. In the southeastern United States, cycles involving several species of mosquitoes and wading birds, along with reptiles, might play a role in maintaining viral transmission during the winter months."
What are the symptoms of EEE?
Even if you are infected with EEEV, the chances of developing EEE is extremely rare. Of humans who are infected with EEEV, only about four to five percent will result in the actual infection.
According to the CDC, it takes four to 10 days after the bite of an infected mosquito to develop symptoms: "Severe cases of EEEV infection (EEE, involving encephalitis, an inflammation of the brain) begin with the sudden onset of headache, high fever, chills, and vomiting. Then, it can progress into disorientation, seizures, and coma."
If you or a family member is showing any symptoms, contact your healthcare provider immediately. They can conduct blood and spinal fluid tests in order to diagnosis.
How is EEE treated?
Unfortunately, there is no specific treatment for it. Antibiotics are not effective against viruses and no anti-viral drugs have been found effective in treating it. Patients are usually hospitalized and treated by supportive therapy, including respiratory support, IV fluids and prevention of other infections.
Tips on preventing EEEV
As with any other mosquito-spreading virus, the best way to protect yourself is by preventing mosquito bites in the first place. The CDC offers the following tips:
- Use insect repellent containing DEET, picaridin, IR3535 or oil of lemon eucalyptus on exposed skin and/or clothing. The repellent/insecticide permethrin can be used on clothing to protect through several washes. Always follow the directions on the package.
- Wear long sleeves and pants when weather permits.
- Have secure, intact screens on windows and doors to keep mosquitoes out.
- Eliminate mosquito breeding sites by emptying standing water from flower pots, buckets, barrels, another containers. Drill holes in tire swings so water drains out. Keep children's wading pools empty and on their sides when they aren't being used.
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