For the first time this year, the West Nile virus has been detected in Massachusetts. On June 13th, the Massachusetts Department of Public Health confirmed that a mosquito sample collected in Shrewsbury tested positive for the virus.
The West Nile virus is mostly found in the central and southern parts of the country, but it can be found anywhere mosquitoes are active. While most people infected with the virus remain asymptomatic, others can develop mild to moderate flu-like symptoms, and in more severe cases, even death.
Dr. Catherine Brown, the state epidemiologist and state public health veterinarian at the Massachusetts Department of Public Health, joined GBH’s All Things Considered guest host Henry Santoro to discuss the virus and how to stay protected. What follows is a lightly edited transcript.
Henry Santoro: Last year, the virus was detected in late June. Here we are, mid-June. Is this something to be worried about, being detected early?
Dr. Catherine Brown: I guess the way I’ve been talking about this is that we’re still within sort of the range of a normal first detection, right? It’s a little bit earlier than we’ve seen in some years, but not wildly unseasonal, right? I mean, if we found our first detection kind of back in April, I would start worrying about things. But at this point, you know, I think we still need to call this kind of average for a starting time.
Santoro: If one mosquito is found with West Nile, does that mean that there are thousands more that have it as well?
Dr. Brown: Always, right? I mean, one of the tricks to doing surveillance for West Nile virus is that, you know, you set these traps and you collect hundreds to thousands of mosquitoes, right, but you can only test some of them. You test a sample of them, but if we find one sample that’s positive, it definitely means that there are others out there that also have the virus.
Santoro: So, you just need one to tip you off, and then you know that it’s here.
Dr. Brown: Yes, absolutely. But I will say it’s really important for us to continue to do this mosquito surveillance throughout the season, right? Because if we test at the beginning of the season and we get one sample that’s positive, but then in four or six weeks we get 10 samples that are positive, that’s really meaningful and it helps us understand how risk increases throughout a season.
Santoro: What are the telltale signs of someone having the virus, and are there serious outcomes if they don’t seek medical attention fast enough?
Dr. Brown: The symptoms for West Nile virus generally include fever, headache, chills, kind of fatigue, you know, fairly nonspecific to be honest. There is no specific treatment for West Nile virus, it’s not like you get antibiotics or anything like that. So, really what’s important is for people who develop very severe persistent headaches, or a stiff neck associated with these other symptoms, it’s really important that they seek medical care. The healthcare provider can provide supportive care, especially if someone needs to be hospitalized. But again, there’s no specific treatment to combat West Nile virus.
Santoro: How worried should Bostonians be about possibly coming down with this virus?
Dr. Brown: I never advise kind of fear, right? That, to me, that’s not the right approach and particularly not this early in the season. Our mosquito-borne diseases here, West Nile virus, it occurs every single year and we see cases every single day but the numbers remain relatively small. Last year was actually a little bit of a big year for us where we had, I believe, 18 human cases of West Nile virus. And that’s a substantial number, so usually it’s less than that. What I’m advising is that people pay attention to the information that we put out during the season so that they can understand when risk gets higher and also learn what they can do to help protect themselves.
Santoro: And so people should probably try to stay indoors right around dusk? And then is it true that the virus or the mosquitoes go away at first frost?
Dr. Brown: Yes, but that’s gonna, it’s gonna take a little while for us to get to the first frost.
Santoro: It’s 101 degrees out right now.
Dr. Brown: Yeah, my phone says it feels like a hundred and seven. I think we have a ways to go. It’s going to get worse before it gets better. But again, just a reminder, this is not a common disease. It’s not like COVID or the flu, where we get hundreds to thousands of people who are infected. And just a reminder to folks that using mosquito repellent and covering up — when it’s not 101 degrees outside —are easy things that people can do to help reduce the chances of getting bitten by a mosquito.
Santoro: Last year, we saw EEE, Eastern Equine Encephalitis. Is there any possibility that that could raise its ugly head this year as well?
Dr. Brown: Absolutely. The fact that we had cases last year, there were four human cases, is actually somewhat predictive of us having additional activity this year. It’s not a perfect predictor, so don’t come back to me later if we don’t have any. But I think at this point in the year, we are anticipating that there will be some EEE activity. Again, we rely on our mosquito surveillance system to really help us understand how risk evolves throughout the mosquito season, and we haven’t had our first detection yet. But again, it’s something for people really to be aware of and to follow the information that we put out during the season so they can kind of track what’s happening.
Santoro: Are the best ways to get Triple E pretty much the same as preventing West Nile?
Dr. Brown: Yeah, that’s the good news — preventing mosquito bites, it’s really the same set of recommendations. So again, using a mosquito repellent that has an EPA registered active ingredient when it’s not super hot and you can use long sleeves to reduce exposed skin, that’s another tool.
Santoro: Does EEE spread fast?
Dr. Brown: The factors that are involved in spreading either of the mosquito-borne diseases are complicated and multi-factorial. So, it involves mosquito populations, it involves infected birds, it involves how much rainfall we have, it involves heat. The answer is that triple-E can spread quickly, you know, can increase the number of mosquitoes that are infected. But it doesn’t have to. It really depends on the specific circumstances that occur during a particular season. And again, sorry to sound like a broken record, but it’s one of the reasons that mosquito surveillance is so important.
