Mosquito-borne illnesses are back in the news. 4 ways to protect yourself.
It’s a bad year for mosquito-borne illnesses: Mosquitoes carrying Eastern equine encephalitis have prompted people in Massachusetts to stay indoors at night. Dr. Anthony Fauci was recently hospitalized with West Nile virus, while one New Hampshire man was fighting for his life after testing positive for three mosquito-borne illnesses, including both EEE and West Nile. More than 20 travelers have returned to the U.S. from Cuba with Oropouche, or "sloth fever." And record numbers of dengue fever cases are spreading globally, including in Puerto Rico and other parts of the U.S. Experts say the surge in human diseases spread by the insects is due, in part, to climate change. But that doesn’t mean you’re powerless against the bugs and the infections they carry.
Find out more about the diseases that mosquitoes are spreading and why — and how to stay safe from their potentially infectious bites.
What illnesses are mosquitoes spreading in the U.S.?
Mosquitoes carry multiple diseases that they can spread to humans, according to the World Health Organization. Some of these primarily affect other countries — especially those in the global south — but several are pressing issues in the U.S. That’s especially true this summer. Some making headlines in the U.S. this year include:
• West Nile virus is the most common mosquito-borne illness in the U.S. It can cause fever, headaches, body aches, vomiting, diarrhea and a rash, according to the Centers for Disease Control and Prevention.
Most people bitten by a West Nile-carrying mosquito never develop symptoms. People over 60 and those with underlying health conditions including diabetes are at a greater risk of getting severely ill and requiring hospitalization. Last month, Fauci spent nearly a week being treated in-hospital for the virus, though he’s now recovering at home, a spokesperson told the Washington Post. Fauci is one of 659 people in the U.S. infected with West Nile virus this year, according to the CDC. Of those, 452 people have had infections that progressed to affect their spinal cords or brains. If the disease reaches this stage, survivors can suffer long-term fatigue and other neurological issues.
• Eastern equine encephalitis (EEE) is caused by a virus that infects animals including horses (hence the name) and birds, primarily in eastern U.S. states. Mosquitoes that bite these infected animals and then bite humans can transmit the virus to us.
EEE causes flu-like symptoms, including fever, body aches and, most importantly, headache. The headache (and sometimes neck ache) that comes with the infection is a sign of the third “E”: encephalitis, or brain swelling. Some people may also develop confusion or can even fall into a coma, Dr. Daniel Kuritzkes, chief of the infectious diseases division at Brigham and Women’s Hospital, tells Yahoo Life. He adds that the disease is perhaps the most concerning mosquito-borne illness in the U.S., because about a third of infected people die, and many who recover have long-term neurological issues, according to the CDC.
“Fortunately, it’s a rare infection,” says Kuritzkes. “Some seasons we [in Massachusetts] might have just one or no cases; others, a dozen or half a dozen. But the problem is that it’s a highly lethal infection.” So far this year, 10 cases have been reported in the U.S. One individual in New Hampshire has died of EEE, officials there said on Aug. 27, while the September death of a New York resident prompted Gov. Kathy Hochul to declare EEE an imminent public threat. There are no effective vaccines or antivirals to treat EEE, so doctors can only provide supportive care, Kuritzkes adds.
• Dengue fever is a virus carried by mosquitoes that live primarily in tropical and subtropical areas, according to the World Health Organization. The disease is most prevalent in South America, Central America, Southeast Asia and in the Caribbean and Pacific islands. It’s also a major issue in Puerto Rico, which declared a state of emergency over the disease this year. The CDC also issued a warning about dengue amid an unusually high number of infections (almost all of which were related to travel) this spring and summer.
Like West Nile, symptoms of dengue fever include a high fever, headache, body aches, nausea and a rash. Up to 400 million people are infected with dengue annually, and there are no specific treatments or vaccines (though rest, fluids and acetaminophen help), the CDC says. However, most cases are asymptomatic and it’s rarely lethal, according to the WHO.
• Oropouche virus, aka "sloth fever," is transmitted by tiny biting flies called midges, and some types of mosquitoes can carry the virus too. The virus primarily spreads among animals including birds, rodents, monkeys and sloths. Humans can get Oropouche from the bites of mosquitoes that previously bit infected animals. The virus commonly causes fever, headache, joint aches and a rash. Less commonly, people can develop neurological symptoms, including eye pain, dizziness or light sensitivity, but the disease is rarely fatal, according to the CDC.
Oropouche virus isn't present in U.S. animals, so mosquitoes here aren't spreading it. But the CDC issued a warning in August that doctors should be on the lookout for possible infections in travelers, after more than 21 cases of the virus in travelers coming back from Cuba were reported to officials.
Why are mosquito-borne illnesses on the rise?
Experts blame three main factors: warmer weather, wetter climates and the ever-expanding human habitat. Mosquito-borne infections “are emerging or reemerging due to a confluence of climate change and urbanization and the ones we’re seeing now are only a start,” Dr. Peter Hotez, co-director of the Texas Children’s Hospital Center for Vaccine Development and dean of the National School of Tropical Medicine at Baylor College of Medicine, tells Yahoo Life.
Mosquitoes breed in warm, still water. So the more it rains and the higher the temperatures climb, the more the bugs see a population boom. And with more development (and travel) near the marshes and swamps mosquitoes prefer, people are bound to get bit.
That’s why Kuritzkes suspects EEE is back in Massachusetts following the state’s particularly wet spring and summer. For dengue, on the other hand, he thinks that immunity rates have fallen cyclically, leaving more people vulnerable to infection this year than last.
4 ways to protect yourself
Drain any standing water. For example, don’t let water collect in unused flowerpots, pools or pool covers, and change birdbath water frequently. Those items provide a perfect place for mosquitoes to breed.
Dawn or dusk? Don’t go out. That’s what Massachusetts health officials asked people in 10 communities to do (the state is also spraying pesticide to try to kill the infectious pests). The types of mosquitoes that are most likely to transmit EEE in the region are most active during sunrise and sunset.
Dress in long pants and sleeves. If you have to be outside amid mosquito season (from late spring to early fall), covering up as much as possible can protect you from the bites of potentially infected mosquitoes. Legs may be particularly vulnerable to dengue-carrying mosquitoes, which “are very skittish and adept at hovering around people, looking for the perfect opportunity to land and take a quick bite,” Chad Huff, a public information officer with the Florida Keys Mosquito Control District, previously told Yahoo Life. “Often, they choose to gravitate towards the lower legs and ankles where they are less likely to draw attention or a slap.” So you might want to take extra care to cover and protect your lower body.
DEET yourself. Make sure to spray yourself with mosquito repellent when you’re going outside, advises Kuritzkes. Take particular care to spray any exposed skin not covered up with the long pants and sleeves, ideally with a repellent containing the safe and highly effective chemical DEET, he adds.
This article was originally published on Aug. 26 and has been updated.
