West Nile Virus & EEE
According to the Centers for Disease Control and Prevention, as of Aug. 21, 47 states have reported West Nile virus infections in people, birds or mosquitoes, with 1,118 of those cases diagnosed in humans, resulting in 41 deaths.
Sharone Green, MD, infectious disease specialist at UMass Memorial Medical Center, answers your questions about West Nile virus (WNV) prevention, symptoms, treatment and more!
Physician
Sharone Green, MD
Q:
What is Eastern equine encephalitis (EEE) and what are the symptoms? Are they different than the symptoms of West Nile virus? Can they also go undetected similar to West Nile virus?
A:
The symptoms of Eastern equine encephalitis (EEE) are similar to those seen with West Nile virus. Both can go undetected. Symptoms come on abruptly and include fever, headache, muscle and joint aches.
In addition, enlarged lymph nodes or a rash on the chest, abdomen or back may be seen with West Nile virus. Encephalitis, which can be characterized by confusion, sleepiness, coma, convulsions or tremors, may develop. Such symptoms should prompt you to seek medical care.
Q:
Why is West Nile virus all of a sudden being detected in so many states, cities/towns? I feel like it is everywhere and I don’t know whether to be worried or to continue on with my day to day life? Can you please provide some insight on this?
A:
This is a good question that I am sure researchers will work hard to answer. At the moment, the reason(s) for the sudden increase in the number of West Nile virus cases in the US is unclear (1590 human cases to date with 65 deaths reported to CDC as of Aug. 28, 2012). One theory is that the especially warm winter has allowed a greater number of infected mosquitoes to survive than usual.
The hot summer in many regions with scattered rainfall here and there can lead to stagnant pools of water, which are the preferred breeding grounds for the Culex mosquitoes that spread West Nile virus. We can’t change the weather, but minimizing standing water near your house (changing water in the bird bath, turning over the kiddie pool after draining it, and removing other items that collect water in the yard) is another way to reduce mosquito exposure.
Q:
Is there a higher risk of kids contracting EEE or West Nile virus? or both? is there a product that protects them from both at once? How often should repellent be reapplied to provide maximum protection?
A:
West Nile virus is much more prevalent than EEE. However, EEE tends to be a much more debilitating disease than is West Nile virus, with a much higher mortality rate, primarily in children. The mosquito that transmits EEE lives in more swampy regions; hence it tends to be detected more frequently in Southern Massachusetts and Cape Cod.
The good news is that the same insect repellents will protect from both of these mosquito species. The timing for reapplication of mosquito protection depends on the type as well as the concentration of the repellent in the product, but can range from 1 to 5 hours. For more information see CDC: West Nile virus
Q:
Would you suggest keeping kids indoors after dusk? With the sun going down earlier and earlier, I don’t know whether this puts the kids at higher risk and more exposure to mosquitoes…
Q:
I read that Lemon Eucalyptus was a natural alternative to DEET. Is there any brand you can recommend if so?
A:
Oil of Lemon Eucalyptus, also known as p-menthane 3,8-diol (PMD), is an Environmental Protection Agency approved, plant-based insect repellent. However, it is considered to be less effective than other chemical-based insect repellents. As a result, this repellent needs to be reapplied frequently in order to be effective.
Brands of repellents vary in their efficacy, based upon the concentration of repellant, temperature, perspiration and water exposure.
Q:
I heard someone talking about pellets or disks of some sort that they put in areas that accumulate water like tarp covers and other areas outdoors? Is this something you suggest if we are concerned about the large number of mosquitoes in our area? (We reside in Westborough, which is one of the towns where mosquito sample detected WNV.)
A:
The pellets or disks that you mention are probably what are known as larvicides. Mosquitoes lay their eggs in water. After hatching they are known as larva (worm-like creatures that swim in the water). Larvae will mature into adult mosquitoes.
The CDC recommends that people drain water collecting areas to reduce breeding sites as the first line of defense. You may find that local hardware stores carry a product called Mosquito Dunks, which contains the bacteria Bacillus thuringiensis israelensis (BTI). If you opt to use these, be sure to carefully follow the instructions as improper use can lead to eye irritation.
Q:
The flu is more dangerous than West Nile, why do we need to spray neuro toxins to attempt to prevent a mild illness?
A:
As there is no specific treatment or vaccine directed against West Nile virus, the only means to protect from this potentially serious illness is avoidance of mosquitoes which can transmit the disease to humans.
Although only 20% or West Nile virus-infected individuals develop symptoms, severe illness due to West Nile virus (meningitis, encephalitis, polio-like syndrome) occurs in 1 in 150 infected individuals. So-called neuroinvasive disease leads to death in ~20% of individuals and may lead to long-term or permanent neurologic symptoms.
Q:
Is there a shot that is given or will be given that protects against all these mosquito sicknesses? I feel like its all we hear about on the news and I want to do whatever i can to protect my kids.
A:
Unfortunately, there are no vaccines licensed for human use against West Nile virus or EEE. There are 4 different West Nile virus vaccines that have been licensed for use in horses. Unfortunately, a study by CDC in 2006 reported that a West Nile virus vaccine would not be cost-effective.
The reason for this is because an efficacy trial (to determine if the vaccine protects against West Nile virus) would need to be extremely large. Because of the sporadic nature of West Nile virus, it would also be difficult to predict the appropriate location for such a trial. For now, the best way to protect your kids is mosquito prevention.
Q:
Is there testing that I can request from my doctor at my annual exam if I want to be tested for West Nile and other viruses carried by mosquitoes? Is this something that would ever be offered at employee health or walk in clinics similar to flu season? I live in a wooded area and they have detected west nile in my town. I have many mosquitoes bites and some the size of blueberries and did have a bout of queasiness last week which is making me paranoid that i have something now.
A:
Testing for West Nile virus, or other viruses carried by mosquitoes, is reserved for diagnostic purposes only. As such, Employee Health or walk in clinics would not perform a screening test for West Nile virus. Since you say that you have many mosquito bites, the best thing for you to do moving forward would be to follow some of the suggestions for mosquito prevention.
As far as your symptoms, only 20% of people infected with West Nile fever develop any symptoms at all. Most people experience a flu-like syndrome known as West Nile fever that typically resolves in a week or two. It is difficult to say what this bout of queasiness was, but if you find that you have persistent symptoms that are bothering you, I would contact your healthcare provider.
Q:
We have a pool at home, does that attract more mosquitoes to our yard than if we didn’t have a pool? My second question is - can West Nile virus be spread without a mosquito bite such as being in a pool where someone who contracted West Nile virus swam after getting a mosquito bite?
A:
Mosquitoes will not breed in chlorinated water. However, if you have a kiddie pool that you fill with untreated water, then this can certainly serve as a mosquito breeding ground. Mosquitoes can lay eggs and hatch in a week, so it is important to drain such pools after each use and to store upside down so that stagnant water does not collect.
In answer to your second question, West Nile virus is not normally transmitted from person to person, so being in a pool or even being in a room with an infected person should not put you at risk. The low level of virus in the blood makes it impossible for an infected person to transmit West Nile virus back to a mosquito.
There have been rare occurrences of person-to-person transmission of West Nile virus via blood transfusion, organ transplantation and even more rarely to infants via an infected mother’s breast milk. Humans are not a part of the normal life cycle of West Nile virus (birds and mosquitoes are the normal hosts).
Q:
If I felt sick the day after I got mosquito bites in three places is that cause for concern? what do I do if I think i have symptoms? what treatment is given?
A:
The typical incubation period (time from the mosquito bite to onset of symptoms) for West Nile virus is 7-10 days. It is therefore unlikely that this illness was related to these particular insect bites. The symptoms of West Nile virus have been outlined above. If you feel that your symptoms are severe (persistent fever, inability to keep down fluids, severe headache, mental confusion or other neurologic symptoms), you should seek your healthcare provider. There is no specific treatment for West Nile virus, but supportive care (e.g. intravenous fluids) might be necessary in more severe cases.
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