A MARTÍNEZ, HOST:
A Massachusetts town is closing its playing fields and parks at dusk to try and stop a nasty mosquito-borne disease from spreading.
MICHEL MARTIN, HOST:
It's called eastern equine encephalitis. Health officials in another town are so concerned, they're even encouraging people to stay home after 6 p.m.
MARTIN: It's called eastern equine encephalitis. Health officials in another town are so concerned, they're even encouraging people to stay home after 6 p.m.
MARTÍNEZ: NPR's Pien Huang joins us now to tell us more. So last week, we talked about parvovirus - sounded like a thing for dogs. This one has equine in the title, so I'm going to think horses.
PIEN HUANG, BYLINE: Yeah, A. This one affects both horses and people, and it's a very rare disease. Overall, the U.S. sees about a dozen human cases of it a year. But it is considered the most deadly mosquito-borne disease in North America. It's got a mortality rate between 30% and 50%, and that's why this recent case in Massachusetts has sparked a lot of concern.
MARTÍNEZ: All right, so tell us about that case.
HUANG: Yeah, so earlier this month in Massachusetts, health officials announced one case of eastern equine encephalitis. They call it Triple E. And this was in a man in his 80s in Worcester County, which is sort of in the south-central part of the state. It's the first human case that they've seen in four years, but also, this year, they've been detecting it in a lot of the mosquitoes they've tested. They found it also in another part of the state called Plymouth, near Cape Cod, and that case was actually in a horse.
MARTÍNEZ: All right, so that's why they're prompting - that's prompting Plymouth to double down on closing their fields and parks at dusk.
HUANG: Yeah, and to not even let athletic teams practice after that, because that's when the mosquitoes that are most likely to spread the virus are biting. I spoke with Catherine Brown about it. She's the state epidemiologist for Massachusetts.
CATHERINE BROWN: This is a recommendation nobody wants to hear kind of at the end of summer. I am entirely sympathetic to that, but it is part of this sort of layered prevention strategy that we have.
HUANG: Brown says that they've also been spraying insecticide in some neighborhoods. And there's no vaccines or treatments for it in humans, so health authorities are telling people to be extra vigilant about wearing good bug spray.
MARTÍNEZ: Yeah. So you mentioned that this virus can be fatal. What are the other risks, though, of catching it?
HUANG: So this virus attacks the central nervous system in mammals, so it can cause meningitis or brain swelling, and even those that do survive often have ongoing neurologic problems. And interestingly, A, humans and horses are actually considered dead-end hosts for this. So usually, there's not enough virus circulating in their blood to spread it on to other mosquitoes, and instead, the reservoir for this virus is actually in birds, which can spread the virus more broadly.
MARTÍNEZ: Is this just a thing in Massachusetts, or have they found it in other parts of the country?
HUANG: Well, so far this year, there have been two other human cases - one in Vermont, and one in New Jersey - but the virus has been found in mosquitoes or birds or other animals out in Michigan this year, down in Florida, Louisiana, South Carolina. These are all areas that tend to have freshwater hardwood swamps, which are places where the birds and mosquitoes that carry the virus tend to mix. I should also say that the virus' footprint has grown over the past 15 years. Brown told me that that's likely due, in some part, to climate change - you know, the warmer temperatures are making the mosquito season longer. Shifts in weather and seasonal patterns really affect when and where the birds are migrating.
MARTÍNEZ: So just to restate - if you're in that area, bug spray, and try and stay indoors after 6 p.m.
HUANG: Yes, that, and also dumping any standing water around you.
MARTÍNEZ: All right. NPR's Pien Huang, thank you very much.
HUANG: You're welcome. Transcript provided by NPR, Copyright NPR.
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