There’s been a lot of attention on mosquito-borne illnesses in recent weeks, after a Hampstead man died from eastern equine encephalitis, also known as Triple E. The rare but serious virus has also been detected in several animals – including multiple batches of mosquitoes – across the state.
Dr. Benjamin Chan, New Hampshire’s state epidemiologist, says it’s not uncommon for these viruses to peak every few years — and Triple E, in particular, is especially active this season.
As more reports of mosquito-borne illnesses pop up around the region, Chan and other health officials are warning people to be extra careful to protect themselves.
“We don't want to scare people,” Chan said. “We want people to go out and enjoy the remaining nice weather, but we want people to be aware that there is risk this season — and, we believe, elevated risk for these viruses — and people should take appropriate precautions to protect themselves against mosquito bites when they're outdoors.”
Read on for more information on how to assess the risks of these viruses and how to stay safe.
Guide to Mosquito-Borne Illnesses from New Hampshire health officials | Latest New Hampshire testing results | New Hampshire Arbovirus Risk Map
What’s the deal with these viruses?
Health officials are closely monitoring three main mosquito-borne illnesses this season: Triple E, West Nile Virus and Jamestown Canyon Virus. All three have been detected in local mosquito batches.
There are no vaccines or other specific antiviral treatments for these infections in humans, Chan said.
“Some people may have very mild symptoms that resolve on their own,” Chan said. “But what's concerning about these viruses is that they can and do cause very severe neurologic symptoms that can lead to infection in the brain, meningitis.”
The symptoms and severity of these illnesses vary, but Triple E can be especially dangerous.
According to the Centers for Disease Control and Prevention, “approximately a third of all people who develop severe eastern equine encephalitis die.” Even for those who recover, the infection is life-altering — causing “mild to severe intellectual disability, personality disorders, seizures, paralysis, and cranial nerve dysfunction,” according to the CDC.
How worried should the average person be about mosquito borne illnesses in New Hampshire right now?
No matter where you live in the state, you should be on alert.
“We're seeing a very active year in terms of mosquitoes that are testing positive, animals and people that are testing positive for these viruses,” Chan said, “not just in New Hampshire, but regionally.”
While most of the cases the state has announced so far have been concentrated in southern New Hampshire, Chan said “that's because that's where we have the mosquito surveillance.”
State health officials monitor data from a few different sources: patients who are tested by their doctors or other health providers, and mosquito testing in a limited number of towns, most of them located in the southern part of the state.
Related story: Manchester’s 'Mosquito Lady' spends her summer attracting the insect most of us try to avoid
What can people do to stay safe?
Some communities have been spraying to control mosquito populations, and more information on those efforts is available here. But Chan said everyone in New Hampshire should be taking extra steps to protect against mosquito bites.
“It's better to be safe than to take the risk this season that comes with mosquito bites,” Chan said.
There are several ways to do that.
Adjust your outdoor plans: Another way to avoid mosquito-borne illnesses is to avoid habitats that attract mosquitoes. Chan said spending time outside on a bright, sunny afternoon is likely less risky than hanging out in a swampy, tree-covered area. You can find more information on the different kinds of areas that can attract mosquitoes here.
Wear insect repellent: Pay attention to whether the repellent is specifically designed to repel mosquitoes. Make sure you’re applying it on exposed skin anytime you’re outside, Chan said, and reapplying if you’re outdoors for extended periods of time. The CDC cautions against using “non-EPA registered insect repellents, including some natural repellents.” You can find more information on how to choose an insect repellent here.
Cover exposed skin: Chan said wearing long-sleeved shirts and pants can also add a layer of protection, but it isn’t foolproof. “Thin, tight-fitting clothing is not necessarily 100% protection against mosquito bites, because mosquitoes can bite through thin layers of clothes,” he said.
Keep the outdoors, outdoors: Health officials also suggest using screens on windows or doors, and making sure those screens are free of holes. The CDC also recommends using air conditioning, if possible.
Get rid of standing water: Doing so can get rid of a prime environment for mosquitoes to lay eggs, according to the CDC. They suggest cleaning up any items that could hold standing water at least once a week, “such as tires, buckets, toys, pools, birdbaths, flowerpot saucers, or trash containers.”
But not all prevention methods are created equal, according to New Hampshire health officials.
“Vitamin B, ultrasonic devices, incense, and bug zappers have not been shown to be useful in preventing mosquito bites,” they say.
What symptoms should people watch out for?
Chan said people who contract a viral infection from a mosquito bite might develop “mild symptoms of fever, chills, muscle aches, joint aches,” and those could resolve on their own.
But he said people should immediately call their healthcare provider or go to the emergency room if they have any of the following symptoms after a mosquito bite:
- Severe headache
- Neck pain that makes it hard to move, which can be a sign of meningitis
- Signs of confusion or changes in someone’s mental state
- Seizures, which can signal a nervous system infection
How does testing work for these illnesses?
It’s a multi-step process.
“One of the first rules with disease investigation is to confirm the diagnosis,” Chan said. “And so there's a whole sequence of events that needs to happen before we can identify and confirm that somebody has a mosquito-transmitted disease.”
First, Chan said, someone has to seek medical attention for their symptoms. From there, a healthcare provider needs to be able to recognize the signs of a mosquito-borne illness and order preliminary testing. Those are often antibody-based tests, Chan said, and can give false positives or lack clarity around what kind of infection someone has.
From there, Chan said, a patient would go through another round of testing to confirm their infection, which can sometimes take weeks. It’s not the kind of routine testing usually done in local hospitals, he said, and it often requires sending the tests to outside laboratories.
“I know that that is oftentimes difficult for families who have loved ones that are ill and in the hospital or sick, waiting to know what is causing the symptoms,” Chan said. “But the reality is that diagnosing some of these types of infections takes time.”
That’s why people might hear reports about additional cases of these mosquito-borne illnesses in the media or elsewhere, before the state independently confirms those cases.
“Triple E and any of these mosquito diseases are reportable diseases, meaning that when somebody is identified with infection, it gets reported to public health so we can investigate,” Chan said. “Right now we only have the one person that has been diagnosed and confirmed to have Triple E.”
How is this affecting animals?
So far, Chan said the state has confirmed four cases of Triple E in horses, for whom infections can also be serious. But there are more precautions available for horses than humans.
“There is a veterinary vaccine for horses, and so horse owners that are out there should take note of this as well and be in touch with their veterinarian about whether to make sure that their horse is up to date on receiving the recommended vaccines,” Chan said.
