A deadly mosquito borne disease known as Eastern equine encephalitis, also known as EEE or triple E, has some communities in Massachusetts on high alert. This is the first outbreak of EEE the state has seen in four years. State officials started spraying in parts of Worcester and Plymouth earlier this week in an attempt to fight the spread. So far, one Worcester man in his 80s has contracted the disease and is currently receiving treatment. And sadly, a 41-year-old New Hampshire man has died after contracting the virus.
Massachusetts State Commissioner of Public Health Dr. Robbie Goldstein joined GBH’s All Things Considered host Arun Rath to talk about the virus and how to stay safe. What follows is a lightly edited transcript.
Arun Rath: So we’ve been hearing about the triple E virus. Can you tell us what the virus is like, what it means to to get this virus? Potentially.
Dr. Robbie Goldstein: Eastern equine encephalitis, or triple E, as we’re referring to it, is a rare disease, but it’s a serious disease, and it is one that is carried by mosquitoes. And those mosquitoes, depending on the species of mosquitoes, have the ability to infect birds and mammals. And when we see the virus in the types of mosquitoes that can infect mammals, including humans, the risk to humans increases. It remains rare, but the risk definitely increases.
The virus itself gets into the body through the bite of the mosquito, and the virus goes to the central nervous system, to the brain and the space around the brain. And it can cause what’s called a meningoencephalitis, or inflammation of the brain and all of the fluid that’s around the brain. Because of that, people can have pretty significant symptoms when they get infected. We can see people who have the normal symptoms of encephalitis or meningitis, so fevers and headaches. But this virus itself can progress and result in altered mental status, fatigue, coma and up to 50% of those who get infected can actually have such significant symptoms that it leads to death for those that don’t die. They are oftentimes left with permanent neurologic disabilities because of how much inflammation happens in the brain.
It’s a very rare disease. It is not in every mosquito and certainly not transmitted with every mosquito bite. But because it is so serious, we take an increase in the risk incredibly seriously at the Department of Public Health.
Rath: And if someone is infected, is that fever the first symptom and how soon after a bite, would one experience it?
Goldstein: What we know right now about the virus is that the incubation period is around four to 10 days. And I give you such a broad range there because it’s really hard to know when someone might have been exposed to a mosquito that had the infection. It may be that people are out hiking in the woods every single day, or it may be that they’re out around dusk or dawn multiple days in a row. And so it’s hard to know exactly when that bite happened. But we think somewhere around four to 10 days after the bite and after transmission of the virus, people will start to develop symptoms and everyone’s presentation can be different. And that presentation varies based on how old someone may be, how many underlying medical conditions they have that can contribute to whether they might present first with fever and some fatigue, or if they may rapidly progress to some of the more serious symptoms like a coma or significant neurologic disabilities.
Rath: Now, in terms of risk level, I want to point people to, there’s an actual risk map on the Massachusetts government website where you can see the relative risk levels for EEE. Could you break that down, though, for us? We can see and say like around Plymouth or Worcester counties, there is an elevated risk level — in most of the state the risk level is rated as remote. What does all that translate to into what we should do? And know?
Goldstein: The Department of Public Health does monitoring of mosquitoes all throughout the summer. And we have a pretty robust program where we work with folks locally and our colleagues at the Massachusetts Department of Agriculture Resources, to bring in mosquitoes to our state lab and test them for the presence of eastern equine encephalitis, as well as West Nile virus. And when we get those data back, we can then translate that into risk within a community. So certainly in communities where there are no mosquitoes that are being identified with triple E the risk is incredibly low. We feel that people are not really at risk when they’re outside over the summer, at acquiring EEE. As we begin to collect more and more mosquitoes, we’ll start to see the virus, perhaps first in the mosquito species that only infect birds, that will increase the risk a little bit, because obviously it’s just a sample, and there might be other mosquitoes that could infect mammals that have the virus, but we’re not seeing them yet. As we begin to see the virus in the mosquitoes that infect mammals, the risk increases further. And then certainly when we have human disease individuals who are infected, we know that the risk is significantly higher. And so we use our map to help people understand what we’re seeing in our laboratory and how that translates to their personal risk.
Rath: And for people who are in the high risk areas. What are the best practices?
Goldstein: You know, we ask people to take a lot of different precautions, whatever makes the most sense for them. We want people to use personal prevention strategies. Those might include things like a mosquito repellent that has an EPA registered ingredient in it that is active against mosquitoes. That will help decrease the risk of mosquito bites. We also think that folks who are spending more time outside in areas of high risk should use long sleeves and long pants to cover their skin to reduce exposure. We also think that there are important things that people can do in their own backyards. They can get rid of standing water. They can make sure that there aren’t puddles that are forming. This helps to reduce the overall mosquito population, though. I’ll point out that a lot of those mosquitoes in people’s backyards are mostly the types of mosquitoes that spread West Nile Virus and not EEE.
Rath: Having mentioned that, could you tell people about about West Nile as well and distinguish that?
Goldstein: So West Nile virus is also a virus that can get into the brain and the area around the brain. It causes a different type of encephalitis or meningoencephalitis. It is less serious of a disease than EEE, meaning most people who get West Nile virus may have a few days of fatigue and maybe some fevers. They may feel unwell, but they usually recover. It’s those people who are at the extremes of age, so they’re really young and they’re really old, and people who are immunocompromised have a weakened immune system for some reason. That can have a pretty significant presentation of West Nile virus.
Rath: And there’s a risk map for that online as well.
Goldstein: There is.
Rath: Do we have a sense of why there is an uptick of cases, why there were, you know, four relatively quiet, or three relatively quiet years ?And now we’re seeing cases again.
Goldstein: Triple E does not happen, or at least EEE disease in humans does not happen every year in Massachusetts. The virus really tends to follow a cyclical nature, where we see about two to three years of pretty intense activity, followed by several years of pretty quiet activity. The last outbreak we had in Massachusetts was 2019 to 2020, and we had 17 human cases and seven human deaths during that time period. But since 2020, we haven’t seen human cases in Massachusetts. So we’ve sort of expected this year, possibly for more cases to present, because we are coming out of a four year period of quiescence.
