So far this summer, mosquitoes in each of the five boroughs have tested positive for West Nile Virus. While no human cases of the virus have been reported in New York City, one case was found in upstate New York.
Should we be worried? Yes, and no.
“While we encourage New Yorkers to enjoy the outdoors, we also want them to take sensible precautions against mosquitoes and avoid potential serious illness, such as West Nile Virus and Eastern Equine Encephalitis,” New York State Health Commissioner Dr. James McDonald said in a recent press release. “Infected mosquitoes look just like regular mosquitoes and can be found in outdoor areas across the state.”
To help us keep safe, we spoke with Dr. Sharon Nachman, the division chief for pediatric infectious disease at Stony Brook Children’s Hospital, where she sees patients and conducts clinical research. Epicenter NYC spoke with Dr. Nachman about mosquito-borne illnesses — including dengue, West Nile virus, and malaria — and what New Yorkers should know as peak mosquito season continues. Edited excerpts below.
Epicenter NYC: What should we do to reduce the risk of mosquito-born illness?
Dr. Nachman: First thing to think about is: Are there mosquitoes on your property? Do you have standing water? When I’m in Queens and other parts of New York, I look around. Are there flower pots that have pools of water in them, or other things that are just sitting there in the backyard collecting water? That’s where the mosquitoes will breed.
If you do have standing water, you are at increased risk for more mosquitoes in your backyard. So a quick check, walk around and dump out the water will really be important.
The second thing is mosquitoes feed the most at dusk and dawn. Most of us are not outside at dawn — well, perhaps in Central Park, the runners are. But at dusk, that’s very common.
A lot of people are outside attending barbecues and parties, walking and hanging out. If you are one of those people, it would be a good idea to use mosquito repellent. We prefer to use a DEET-containing spray. We don’t like to spray it on children’s arms and legs. We spray it on their clothing. That’s a great mosquito deterrent. Adults — we worry less about them absorbing DEET on their skin, so maybe you can use it on your skin.
People always talk about citronella, etc. Unfortunately, most of those don’t seem to work very well.
Epicenter NYC: The difference in applying DEET for children versus adults — is that because children’s skin is more sensitive to absorb?
Dr. Nachman: They tend to absorb more. Their body surface area is quite different than with adults, and we worry about how much they are absorbing. An occasional amount on their skin — not so much of an issue. But children are outside much more than adults. So for that reason, I like to use the DEET on their clothing, not their skin.
Epicenter NYC: What are some early symptoms for both dengue and West Nile virus?
Dr. Nachman: Unfortunately, a lot of the early symptoms mimic other viruses. You and I could have said this in winter with the flu: “I have a headache, some fever, my arms and legs hurt.” Now it’s summer: “I have a headache, fever, my arms and legs hurt.” It really depends on how quickly you’re getting better or not, and what else is going on.
We tell families: If the child is not able to keep fluids down or not drinking, that’s a reason to come to the hospital. If they’re able to eat and drink, and all they have is fever but otherwise they’re hanging out, you’re probably okay. But if they’re not eating and drinking, those are the kids and adults we want to get seen.
On the adult side: if you have a severe headache, light bothers your eyes, you have a stiff neck and can’t bend it — those are symptoms that need to be seen.
Epicenter NYC: How do you best seek treatment after getting a mosquito bite?
Dr. Nachman: Some children and adults have a very big response to a mosquito bite. Their arm swells up, it’s red, hot and tender. It’s important to tell someone that it started as a mosquito bite and was scratching and itching, because otherwise, when you come in, someone may think it’s cellulitis. The treatment is quite different.
Be smart about giving your history when you go to the doctor. Tell them everything. Don’t edit what you tell the physician — they need it all to make the right diagnosis. We’re seeing the routine mosquito-borne infections, but we’re also seeing some cases of West Nile. As you can imagine, in children it’s often just a flu-like illness. It’s in the adult population that we seem to see more severe consequences from West Nile.
The incubation is two days to about a week or so. Do you remember which mosquito bite you got a week ago? I certainly don’t. But when you come into the emergency room, it’s important to remind people that, yes, I did get lots of mosquito bites and here are my symptoms now. Unfortunately, similar to dengue, we do not have any medication that will make the West Nile virus better. We can’t treat it.
But if you are sick, the supportive measures we do with dengue are pretty much the same supportive measures we do with West Nile. So if you are feeling sick, it’s important to get seen. We certainly can test for these mosquito-borne infections and we can help maintain you while you’re getting better. But it is summer. Families are traveling all over — including Florida, Puerto Rico, the Dominican Republic, Brazil — and they’re certainly coming back with their dengue.
Epicenter NYC: For those at higher risk, like older adults or immunocompromised individuals — who are at higher risk of more severe symptoms — has your guidance changed with the presence of West Nile virus?
Dr. Nachman: We don’t want to lock up all those individuals and tell them they can’t hang out outside, but we want to tell them: use the repellents — they definitely work. And be smart. If you’ve been outside and you have symptoms, get seen. Call your doctor and let them know what your symptoms are. It could be unrelated and treatable for another reason, but knowing is half the battle. Particularly if you have severe symptoms, don’t sit around and wait. Talk to your doctor. With the advent of telemedicine, it’s easier to get someone to talk to you and get direction.
Epicenter NYC: How would you say local health agencies are handling mosquito control this season? I haven’t heard anything about any mosquito spraying events yet.
Dr. Nachman: They do talk about spraying. We often don’t hear about smaller sprayings. The Departments of Health also look at how many patients are infected and their zip code. If they’re seeing a high-risk zip code, that’s where they’ll direct their spraying. They can’t spray all of New York, or all Queens. But if they are seeing a particular hot spot, that’s where they’ll go. That’s what they’ve done in the past, and it certainly helped.
They’ve done a good job with mosquito control in the past. It’s up to everyone who sees patients to test for those viruses, because that’s how the state will know: “Oh, we are seeing more West Nile in this zip code or that zip code,” and here’s where we should spray.
Epicenter NYC: Could someone be infected with both West Nile virus and another mosquito-borne disease like dengue?
Dr. Nachman: That’s very rare. We see both illnesses at the same time, but could it happen? Of course. If you’re in New York, most likely you will have West Nile. If you’re traveling, most likely, you’ll have dengue. What’s interesting about Long Island populations is that after 1999, when we had our first events of West Nile, most of the population is now immune. So while we worry about it, the risk is actually quite a bit lower because so many of us have seen the virus. Occasionally you get someone whose immune response is non-existent, and for them it’s a new infection. But the vast majority have probably had a mild case and didn’t know it.
Epicenter NYC: Last year, you mentioned dengue cases were increasing mainly due to more travel, more testing. Is that still the case?
Dr. Nachman: We are certainly noticing that they’re happening more frequently. Certainly we are definitely seeing dengue in the families that are returning from the Southern Hemisphere — Dominican Republic, Florida, Puerto Rico, et cetera. I think it’s because families know that we’re thinking about dengue, and when they come back from vacation and have high fevers and they’re feeling poorly — or the kids are feeling poorly — they’re coming to the emergency room.
And in fact, we are testing them for dengue and finding positives. Remember, dengue testing is a straightforward blood test. It’s not a medical mystery. We know how to test for it, we know how to order the test, and it comes back relatively quickly. So we’re able to identify those children and the adults with dengue.
Dr. Nachman: We are seeing a few cases of malaria as well. Families are traveling to mosquito areas that do carry malaria. The important thing is to talk to your child’s pediatrician or talk to your doctor, and if you’re going out of the country, we’re going to check where you’re going. If you go into an area that does have malaria, it’s really important to remember that we can give you prophylaxis so that you will not come back with your malaria.
Epicenter NYC: What’s the best way to check whether you’re traveling somewhere that may have malaria?
Dr. Nachman: The CDC has an open-access webpage where you can type in where you’re going and you’ll see, with a drop-down menu, what are the diseases we worry about and what are their preventive measures. It’s really straightforward.
Epicenter NYC: You’ve stressed that climate change was expanding the mosquito range, but that dengue still isn’t spreading locally — most cases are travel-related. Can you speak to how climate change is affecting mosquito range?
Dr. Nachman: It’s a very slow-moving target. People don’t notice climate change in small increments. If a volcano erupted, we’d all notice. But it’s those little changes we don’t notice. I think more about the storms. People say, “Oh, it’s a once-in-a-hundred-year storm.” But if we’re having two that summer, that’s two too many. All those weather events contribute to mosquito pools being pushed further north. While we’re not seeing native dengue here — meaning mosquitoes in New York carrying dengue — will that time come? I worry about that, as do other physicians.
Epicenter NYC: Are there any indicators other mosquito-borne viruses could become more widespread here in New York in the future?
Dr. Nachman: Certainly. We do worry that dengue and chikungunya — which is another virus those mosquitoes carry — those mosquito pools will travel up the coast and perhaps eventually wind up here in New York. It may take a few years, and a lot of it has to do with global warming: where the mosquitoes are, where the food is, and how far they can travel.
Remember, mosquitoes can fly for about a mile, so it’s not like they’re just staying on your block. Every year: a mile, a mile, a mile — soon they are coming up the highways up to New York. Is it going to happen instantly? No.
The things that we can do about it include getting rid of the mosquito pools, the standing water, using mosquito repellent, and being smart about where we are. We all worry about the change in temperatures in our environment, making it easier for mosquitoes to travel longer distances for longer months.
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