How to avoid mosquito-borne West Nile virus, EEE

[00:00:00] Host Amber Smith: Upstate Medical University in Syracuse, New York invites you to be "The Informed Patient" with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith. A pair of mosquito-borne diseases have been in the news lately. So I'm turning to Upstate molecular biologist, professor Saravanan Thangamani, to tell us about these mosquitoes and explain how they transmit West Nile virus and Eastern Equine Encephalitis. Welcome back to "The Informed Patient," Dr. Thangamani.

[00:00:33] Saravanan Thangamani, PhD: I'm happy to return back.

[00:00:34] Host Amber Smith: People have died from diseases transmitted by these mosquitoes, so it's pretty serious. What do we need to know about Triple E and West Nile virus?

[00:00:44] Saravanan Thangamani, PhD: Well, mosquito-borne diseases are actually a major problem for the Northeastern United States, specifically the West Nile Virus, and we call it Triple EV, or Eastern Equine Encephalitis Virus. As the name suggests, it primarily infects equine or horse, but humans are accidental host. And if we get that virus infection, it can lead to fatal consequences.

West Nile virus was originally introduced to the United States in 1999. It was originally discovered in the New York Bronx Zoo, then eventually exploded throughout the United States. Now it is in the news because lately more and more infections of West Nile virus are being reported in the United States, and we are seeing mosquito positives. Pools of mosquitoes are positive for West Nile virus.

Largely it causes asymptomatic infection in humans. I would say 80% of the humans who get mosquito bites that carries the West Nile virus do not develop any symptoms. However, one in five will develop acute febrile illnesses, and one in 150 people actually get into serious symptoms of neurological infection, such as the infection of the central nervous system, such as encephalitis or meningitis. So that's where it becomes really problematic, particularly in a population greater than 50 years old, because that's where your immune system starts to slow down. Immune systems start to respond slowly. And that's when the virus actually causes heavy damage to public health, is that people who are over 60 years of age or at the greater risk of West Nile virus infection.

So this is a mild disease, as I said, is asymptomatic in majority of the cases. However, if it infects the central nervous system, it can lead to fatal, or severe health consequences, primarily infecting the spinal cord and brain.

[00:02:38] Host Amber Smith: Now are we talking about, is it the same mosquito that carries EEE and West Nile virus, or are they different?

[00:02:44] Saravanan Thangamani, PhD: No. So those are two different mosquitoes. So West Nile virus is primarily transmitted by a mosquito, in the genre, Culex mosquitoes. There can be Culex quinquefasciatus, or Culex pipiens, and Culex tarsalis. They all can actually transmit West Nile virus. Those are primarily bird feeding mosquitoes. Again, I'm telling that humans are accidental hosts. This particular mosquito, they prefer to feed on birds. And then humans become accidental hosts because we try to -- human behavior, right? -- we try to live closer to the woods, we try to venture into the woods, trekking and other things. So that puts us closer proximity to these mosquitoes that prefer to feed on birds.

The triple E virus, on the other hand, is transmitted by another mosquito species called Culiseta melanura, so it's a completely different mosquito than the one that transmits West Nile virus.

[00:03:40] Host Amber Smith: Are both of these mosquitoes potentially in Central New York?

[00:03:44] Saravanan Thangamani, PhD: Yes, we do have both in our area. And Culex mosquitoes are present throughout the United States, and Culiseta mosquitoes are especially present in the Northeastern and the South, I would say some parts of Florida, but definitely in higher densities in Northeastern United States.

[00:04:04] Host Amber Smith: It seems like we're hearing about this more. Are there more mosquitoes, and are they more of a threat to us now than they were in the past?

[00:04:12] Saravanan Thangamani, PhD: I would say yes. And it's primarily due to human behavior and climate change. And, you know, these are the dominant mosquitoes that are of human health importance in the northeast United States.

However, we know there are other mosquitoes like aedes aegypti and aedes albopictus that transmit viruses that cause diseases such as Dengue virus, Zika virus and Chikungunya. But they are not present in Central New York, at least to our knowledge. As of today, they are not present in Central New York, but if you go to tri-State area, or New Jersey and other places, you will see those mosquitoes.

[00:04:48] Host Amber Smith: Well, I want to ask you a little more specifically about both West Nile and Triple E, but once a person is infected with either of those, are they infectious to other people?

[00:04:59] Saravanan Thangamani, PhD: No. So these viruses are transmitted to humans only through mosquito bites, not through any other means. So there is no human-to-human transmission in this case. So it is purely through mosquito bites. So you have to have a mosquito bite, provided the mosquito carries a good amount of virus in it, that it injects to the human to cause a disease.

[00:05:23] Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith. I'm talking with Professor Saravanan Thangamani. He's a microbiologist and immunologist, and his laboratory focuses on the biology and ecology of virus transmission.

Dr. Anthony Fauci disclosed that he was hospitalized with West Nile Virus for a week recently, and he said he'd never felt sicker in his life. Does this mean he was bitten by an infected mosquito that was carrying West Nile. Is that the only way he could have gotten it?

Yes. I've been reading in the news -- however, these days I don't know how much I can trust the news media -- apparently there was a report that he got bitten by mosquitoes in his backyard. So it's obviously he got bitten by a West Nile virus positive mosquito. And he's in the higher risk group, which means that, as I said earlier, people over 60 years of age are at the greater risk of getting infected or getting a productive infection, right? So I think, in my opinion, he's one of those very few human cases where he got probably inflammation to the central nervous system or infection to the central nervous system. Is there a test to determine that he was bitten by West Nile, or how is West Nile diagnosed?

[00:06:37] Saravanan Thangamani, PhD: So, laboratory testing, like any other disease condition is through either the blood or the spinal fluid. And most of the virus infection to the central nervous system are diagnosed through spinal tap fluid. So basically they take their spinal fluid, and then they look for either the antibodies or the viral nucleic acids. You go to the doctor, only when you are acutely ill, right? You don't go at the early stage. So these viruses, they actually move away from the blood very quickly, and they infect the target organs. Which means that if you are not going within the first five, six days after a mosquito bite, your blood is of no value. I mean, you can't detect the virus in it. But if you want to look for the actual viral signatures, like actual virus or viral nucle acid, spinal taps are the good samples to do because the virus infects the central nervous system, which means that we will be able to isolate the virus or identify the virus in the spinal fluids.

[00:07:33] Host Amber Smith: How is it treated?

[00:07:35] Saravanan Thangamani, PhD: At this time we don't have a vaccine, so it's more of a supportive therapy and antiviral therapy, depending on different clinicians, you know, they might use different antiviral therapies. But there is no FDA-approved treatment for West Nile virus, at least as of today.

[00:07:52] Host Amber Smith: And at least one community where EEE has been found has been asking residents to stay indoors at dusk to reduce the risk of mosquito bites. Is this a smart strategy?

[00:08:05] Saravanan Thangamani, PhD: I don't think so. I mean, it's my personal opinion. So this doesn't represent Upstate's opinion. This is my personal opinion.

You know, people need to be aware of mosquito bite prevention as well. So wear long sleeves, wear light color clothes and applying certain repellent before you get out in the outdoor activity. And then, if we store stagnant water, like a water in a pan, we should actually flip them upside down. If you have a stagnant water lying in our garden somewhere, or flower pots or bird feeders, those are the places the mosquitoes will come and lay eggs. So if we can try to avoid those kind of mosquito habitats, we can actually go out and have a good lifestyle without us getting worried and locked us in.

And I think that I do not agree with the strategy, because there are many ways how we can prevent getting tick bites.

[00:08:53] Host Amber Smith: What about swimming pools? Now that's chlorinated water. Does that attract mosquitoes like plain water would?

[00:09:00] Saravanan Thangamani, PhD: No, they wouldn't because it's, as you said, it's chlorinated. You know, it essentially kills the... Even if the mosquito come and lay the eggs, the larvae will die. Even if the larva hatches, the larva will die. So basically there is no way those water will actually aid larva growth.

That's why even if you got bird feeders, you can actually buy bricks that you can put in your bird feeder that can actually kill the larvae, but it's not harmful to the birds. So you can buy those things. You can still have bird feeders, like water for the birds in your backyard, at the same time, not aid mosquito growth and perpetuation as well. So there are different ways how we can control your backyard for mosquito growth. Educating the public is very important because we can't scare from every single pathogen or a disease, then we cannot enjoy our life.

[00:09:51] Host Amber Smith: You mentioned wearing light colored clothing. What difference does that make?

[00:09:55] Saravanan Thangamani, PhD: Dark colored clothing tends to attract mosquitoes. So wearing light color, you don't have, mosquitoes doesn't land on you. And again, there are research that people are doing that why someone is more attractive to mosquito bites than others. There's a lot of theory going on. It is our body microbiome and, you know, every person's body emits different odors that attracts the mosquitoes to different levels. And also the body heat is also an attractant for the mosquitoes as well. So there are different reasons why a mosquito is attracted to a particular human, but wearing light color clothing, it actually, you are not a attracted to the mosquitoes, generally.

[00:10:37] Host Amber Smith: Now, you mentioned that most people who contract West Nile virus don't have any symptoms. Is that the case with triple E, or do you have symptoms when you develop that?

[00:10:47] Saravanan Thangamani, PhD: Well, triple E is almost the same. You know, during the acute phase you don't actually get any symptoms. So most of these arbovirus, or the viruses transmitted mosquitoes or the ticks, in the early stage, you don't see any symptoms.

But, similar to the West Nile, triple E also cause similar symptoms because these are encephalitic viruses. They cause encephalitis in humans, but triple E is very rare.But it's fatal. So 30% of the people who shows productive infection can actually succumb to the disease.

When we talk about the West Nile virus, one in 150 people are actually showing productive central nervous system infection.

But here, 30% of the people who actually are exposed to the virus can develop severe encephalitis. So its case fatality is very high here.

But in terms of symptoms, they're all the same. The behavioral changes will happen, drowsiness will happen, seizures will happen, severe headaches will be noticed. But if you connect those symptoms together with, "hey, I'm living in an endemic area that are known to have this particular mosquitoes," then the clinician will put these puzzles together: "OK, now I need to look for this person. Let's take this final tap and I'll look for it." So this epidemiological information is very, very important for the clinicians.

So the constant surveillance, like our county, Onondaga County, is doing constant surveillance for these mosquitoes. So that actually helps the clinicians to know what is happening in our own back yard.

[00:12:19] Host Amber Smith: So if you know that you've been bitten by a mosquito, is there any way to tell from the bite whether something was transmitted?

[00:12:27] Saravanan Thangamani, PhD: Yes, you can tell. You can actually take a punch biopsy from the site of mosquito bite, and then you can look for some viral signatures there. But it depends on how quickly after a mosquito bite they come. Because the virus are pretty good in actually establishing infection in the skin and then disseminates to the target organs. Within a day or two, they will disseminate.

But you know, I don't think that our medical practice will allow us to take a punch biopsy and then look for the virus. They would rather take a blood or spinal tap. Yes, they are a little invasive, but it's better than having a (punch biopsy) scar for your life.

[00:13:02] Host Amber Smith: So if someone gets bitten by a mosquito, they need to wait for a few days to see if they become ill?

[00:13:10] Saravanan Thangamani, PhD: Yes. Mosquitoes feed on humans just for a few minutes, right? So you can't actually capture them and send it to a lab for testing. So if you feel like you got exposed to mosquito bites, a good number of mosquito bites, I would be advising them to look out for any symptoms of acute febrile illness. Are you getting fever? Are you getting tired? Are you getting headache? Are you getting lethargic? Those are the symptoms that you are sick.

That sickness could be directly related to a mosquito bite, whether it is West Nile or EEE V, you are now getting sick post tick bite. So it is always important to go to the healthcare provider as early as possible. As early as you actually notice those acute febrile illness. And then the healthcare provider, based on the epidemiological information, can decide what to do for it.

Because the good thing is that the blood and the spinal type are required for both West Nile and EEE V. So they can actually look for both the virus signatures in these samples and then find out is it West Nile or Triple E V? But one thing I must tell is that there is no treatment, right? Only supportive therapies available at this time, antiviral therapy, depending on the healthcare provider might give, but again, only supportive therapy is available at this time.

[00:14:27] Host Amber Smith: Well, this has been very informative. Thank you for making time for this, Dr. Thangamani.

[00:14:33] Saravanan Thangamani, PhD: Thank you for having me.

[00:14:35] Host Amber Smith: My guest has been Dr. Saravanan Thangamani. He's a professor of microbiology and immunology at Upstate. And the Thangamani Lab focuses on biology and ecology of virus transmission. "The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe. Find our archive of previous episodes at upstate.edu/informed. If you enjoyed this episode, please tell a friend to listen too. And you can rate and review "The Informed Patient" podcast on Spotify, Apple podcasts, YouTube, or wherever you tune in. This is your host, Amber Smith, thanking you for listening.