West Nile Virus and Insect Borne Diseases

WebMD Live Events Transcript

West Nile virus is making its way from coast to coast. And Lyme disease and Rocky Mountain spotted fever are still out there. We talked about insect-borne illnesses: precautions, insect control, symptoms, and more with our "diseases in the news" expert, Georges Benjamin, MD, and Virginia Caine, MD, on July 27, 2004.

The opinions expressed herein are the guests' alone and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.

MODERATOR:
Welcome, doctors. It is great to have two public health experts with such a depth of knowledge about infectious disease with us today. Let's start off with questions about West Nile disease.

MEMBER QUESTION:
West Nile was confirmed in our neighborhood this summer, so the local municipality is sending out the sprayer trucks. Are the chances of getting West Nile so great that we have to breathe this pesticide? What else is it killing besides the mosquitoes? What about my dogs who spend a lot of time outside?

CAINE:
Most of the mosquito trucks spray a biodegradable product so that the chemical agent usually dissolves within 30 minutes. But if you have allergies or certain respiratory disorders, we usually like to give a 24-hour notice, so you can make sure all your doors and windows are shut and can try not to be out in that air within the 24 hours after spraying in the outside environment.

BENJAMIN:
Also, many communities use a variety of mosquito-control efforts, so in addition to the spraying there are other methods. The most effective thing is getting rid of standing water.

CAINE:
Such as no abandoned tires.

BENJAMIN:
Secondly, there are larvacides. These are things you can put in water, so if you have a pool or fish pond they get rid of the baby mosquitoes. But getting rid of standing water is a very important thing people can do. You will be amazed where you can find standing water:

  • Wading pools
  • Pots and planters around the yard
  • If you have a swing that has an indentation in the swing, and that swing is not used very often, it can hold water after rainfall
  • Gutters that are backed up
  • Toys or tools that are left in the yard
CAINE:
We ask anybody who has a wading pool to change the water on a weekly basis, if they can't get rid of it on a daily basis. Birdbaths should be cleaned too, as well.

MEMBER QUESTION:
Are mosquitoes only a risk at dawn and dusk? Is that the only time they are out (do they sleep during the day)?

CAINE:
You're at the highest risk from mosquitoes from dusk to dawn. That's their time for feeding, so your chances are higher of getting bit, but mosquitoes can bite you any time of the day.

BENJAMIN:
Also, when West Nile first entered the U.S., the type of mosquito that was infected tended to be more active in the dusk and the dawn; however, in some parts of the country we're beginning to see mosquitoes that are infected that bite at any time. So the recommendation about dusk and dawn is still valid, but people, if they're going out camping or out picnicking or outdoors, should always protect themselves from mosquitoes.

CAINE:
People should think about using protective clothing and also using a propellant spray containing DEET. The DEET should not be sprayed on a person's skin, but on the clothing items.

BENJAMIN:
You should read the product insert very carefully and talk with your doctor about using DEET with young children. There are some cautions about using DEET with young children.

"In some parts of the country we're beginning to see mosquitoes that are infected that bite at any time. So the recommendation about dusk and dawn is still valid, but people should always protect themselves from mosquitoes."


MEMBER QUESTION:
What is the name of the virus that causes West Nile disease (etiological agent(s))? What is the incidence of West Nile virus found in the Washington metropolitan area? Has anyone or any institution cultured the agent?

CAINE:
The virus can be isolated from the blood of three-fourths of patients on the first day. I think it's primarily a serologic test.

BENJAMIN:
Yes, they can identify the virus, but that's not the important issue. The important issue is of the people who get infected, nearly 20% get West Nile fever. Of those who get ill, less than 1% gets the severe form of disease. The more we know about this disease the more we're discovering more people have been infected, but the good news is the vast majority of people don't get ill.

I'm not aware of reports in the Washington, DC, area this season. We certainly know it's in Washington, DC. The first case in the region was in Baltimore, Md., nearly three years ago. It has been detected in Maryland, the District of Columbia, and Virginia. It should be expected that the disease will return, maybe later this summer.

MEMBER QUESTION:
What are the symptoms of the West Nile virus?

CAINE:
Usually anywhere from one to six days after being bitten a patient can present with:

  • Fever
  • A severe frontal headache
  • Muscle aches or myalgia
  • A cough
  • Swollen lymph glands around their neck
For those patients who are sicker, they may also note a skin rash on the trunk of their body, and if it's severe, they develop an encephalitis picture where they have:
  • High fever
  • Neck stiffness
  • Stupor
  • Disorientation
  • Coma
  • Convulsions
  • Muscle weakness, possibly even paralysis
BENJAMIN:
Just to add on to remind the audience, the more serious symptoms are very rare, but obviously serious when they occur, and the symptom combination of fever and headache and confusion should always encourage someone right away to go to the doctor.

CAINE:
Less than 1% of persons infected with the West Nile virus will develop severe illness.

BENJAMIN:
That means having more than the fever.

MODERATOR:
What is standard treatment for an infection of West Nile virus in those who develop symptoms?

BENJAMIN:
Again, supportive care. For people who simply have a fever, muscle aches, and don't feel well, that means rest, fluids, ibuprofen, Tylenol for the fever, or another antifever medication, and the symptoms usually go away in a few days.

Should someone have the more serious version and require a doctor's care or being put into the hospital, it's supportive therapy with intravenous fluids, medications to control the fever, and in some of the severest cases, if the brain or respiratory systems are involved, the doctors have to use more sophisticated techniques to get the person over this. Most of these individuals do recover with supportive care.

"The more serious symptoms are very rare, but obviously serious when they occur, and the symptom combination of fever and headache and confusion should always encourage someone right away to go to the doctor."

MEMBER QUESTION:
In June 2002, a friend of mine had a severe case of West Nile virus and developed viral encephalitis and viral meningitis. He continues to suffer from severe fatigue, lack of sustained energy, stiffness in knees, stiffness in neck, and a decided change in gait. As he often says, "After West Nile, I seem to have gone to h... in a hand basket." Is his condition a common post-West Nile condition, and how long can he expect to have the pain, etc.?

BENJAMIN:
This is a recognized complication of West Nile virus of the severe form. I cannot tell you what his clinical course will be. We don't know enough about the disease. It's not common, but it does occur in its most severe form. It's a caution and wake-up call to us to control mosquitoes in and around our community. I'm sorry for what happened to your friend.

MEMBER QUESTION:
What is the mortality rate among those patients who have the most severe symptoms?

CAINE:
The overall case mortality rate ranges from 3% to 15%, and it's highest among the elderly.

BENJAMIN:
That's amongst those people who have the most severe, which is less than 1%.

CAINE:
For those without the most severe, the case mortality rate ranges probably closer to 3%. It's almost never fatal.

BENJAMIN:
I've heard that people who have had polio should be very careful of West Nile because it's another horned-cell virus like meningitis. It would be harder on us? Is this info correct? We should be extremely careful?

BENJAMIN:
I think the issue is that people who have had previous neurological disease caused by virus may have some sensitivity when they get a new viral disease that affects the brain, and they may be more sensitive to that. I don't know if that's true or not, but I think the concern that I would have, of course, is again people should protect themselves from mosquitoes, because we know that while the vast majority of mosquitoes don't carry disease, it's a simple prevention we can take, and why take the risk?
MEMBER QUESTION:
What is the role of birds in spreading the disease? I keep hearing about birds in reports about West Nile but don't quite understand their role in all of this.

BENJAMIN:
The issue is that the mosquito that is infected often bites other animals, then those animals get infected and other mosquitoes bite that infected animal and infects other mosquitoes. You get into a cycle where the mosquito that is infected bites a bird, some of those birds get very sick and die, but before they do so they are bitten by other mosquitoes who then get infected, and it's a cyclic pattern.

What happens for people is that we're intermediaries; we get in the way. An uninfected mosquito bites an infected bird, gets infected, and then bites a person and infects that person. This is a side event to the cycle of the mosquito biting the bird and other mosquitoes biting the bird. The same thing happens with horses.

MODERATOR:
When you get infected do you develop immunity to future infections of West Nile?

CAINE:
We think it is assumed immunity will be lifelong; however, it is possible that the immunity may wane in later years.

MODERATOR:
Are there other diseases that can be spread by mosquito bites in North America?

BENJAMIN:
Sure. The most famous, of course, are malaria and yellow fever, although they are not very common on our continent. We have had some resurgence of the mild form of malaria. Three years ago in the Washington metropolitan region we had a couple cases of malaria, presumably from mosquitoes in the region. Worldwide, malaria still is one of the leading killers. The good news is it's not common in the U.S., and even better news is the same prevention methods for West Nile virus are effective for all mosquito diseases, so getting rid of standing water, avoiding high-biting times of dusk and dawn, fixing the screens of your home so the mosquitoes can't get in, and using appropriate clothing are all effective.

"Ninety percent of people with Lyme disease get sort of an expanding circular red rash, and the trademark is you may have a partial central clearing inside the rash."

MODERATOR:
All the more reason to follow the prevention methods you both have recommended. Now let's take a look at tick-borne diseases. What's happening with Lyme disease this year in terms of prevalence?

BENJAMIN:
We still see Lyme disease; it's probably the most common tick borne disease in the U.S. Lyme disease was first named for Lyme, Conn., and it resulted in its worst form, a form of arthritis and other organ damage. But it is a disease that can be treated. The best treatment, of course, is prevention, and that involves avoiding tick bites, or if one is bitten by a tick, removing that tick from your skin.

What ticks tend to do is bite and burrow under the skin, so for people who are in areas of the country where ticks are common they should look on their skin or ask someone else to look at their back and neck, and look for the ticks. The good news is you can see them; the bad news is they're very, very small.

There are simple ways to effectively remove them: Take a little bit of fingernail polish or a little oil on a Q-Tip and put that on the back of the tick. The tick will back out. I don't encourage people to put kerosene on their skin, but that has also been recommended. Don't smash it, because smashing it pushes the venom into your body. So what you try to do is try to grab the head and pull it out with some tweezers or flip it out with a sterile needle.

CAINE:
Some people have used a lighted match brought close to the tick, but don't burn yourself! We want to remind people that a tick should never be removed with exposed fingers, because a tick crushed between fingers may give you the disease.

It takes at least one to four weeks after the tick bite for the symptoms to appear. Ninety percent of people with Lyme disease get sort of an expanding circular red rash, and the trademark is you may have a partial central clearing inside the rash.

A lot of people will complain of feeling tired, a lot of lethargy, but later about 15% of these patients weeks later go on to present with a neurological problem such as meningitis. Or as long as two years later they can develop the frank arthritis that Dr. Benjamin was talking about earlier. MODERATOR:
In what part of the country does Lyme disease occur most frequently?

BENJAMIN:
I think where there's a high risk of ticks, particularly in the Northeast, from the Carolinas up north.

CAINE:
Ninety percent of reported cases come from Connecticut, Maryland, Massachusetts, New Jersey, New York, Pennsylvania, Minnesota, and Wisconsin.

BENJAMIN:
We need to point out there is an antibiotic treatment. Tetracycline is often used, and also penicillin, as an effective treatment. Talk with your doctor about it if you're concerned about it.

MEMBER QUESTION:
There's a treatment, but is there prevention besides not getting bit?

BENJAMIN:
I'm not aware DEET works for ticks.

CAINE:
Not that I'm aware of.

BENJAMIN:
Check the package insert. It's over the counter.

"A lot of us are concerned about the various infectious diseases around, but if anyone has any questions they should go to the web site for the health department for their state."

MODERATOR:
Another tick-borne disease is Rocky Mountain spotted fever. Can you tell us a bit about it?

BENJAMIN:
It's a disease that got its name because it was first seen in the Rocky Mountains. Interestingly it, like Lyme disease, is seen in the same areas, primarily in the Northeast, but also down to Georgia and Tennessee. It has been diagnosed in Canada and Brazil, so it's pretty widely seen.

It has similar physical symptoms to Lyme disease, in that people often get fever and headache and rash. The difference is if they're going to get the rash it's usually early. After seven days they're going to get sick, on average, unlike Lyme disease (which is usually a week or two later), anywhere from one week to four weeks later after the bite.

They also can get a rash, bit it's a different kind of rash. It usually starts on the wrist and ankles, moves to the palm and soles of the hands and feet, and then goes to the main body. It can also be treated with an antibiotic. Tetracycline is the drug of first choice.

CAINE:
The main symptoms for Rocky Mountain spotted fever are a sudden onset of a headache and photophobia -- the light bothers your eyes and you may complain of pain when moving your eyes. An interesting finding about the rash you develop starting out pink; it can turn dark red or purple.

MODERATOR:
So anyone who is out hunting, camping, or hiking anywhere in the U.S. or Canada should follow precautions -- use of insect repellant appropriately, wear appropriate clothing, and inspect for tick bites.

BENJAMIN:
That's correct. Let me add another important point: A lot of us are concerned about the various infectious diseases around, but if anyone has any questions they should go to the web site for the health department for their state. There's usually lots of information about these diseases on the web sites.

In addition, there is the U.S. Centers for Disease Control web site, which is at www.cdc.gov, and there are many books out there about infectious diseases. The Communicable Disease Manual is put out by the American Public Health Association. If one goes to www.apha.org, our web site, you can purchase that book if you're interested in infectious disease. That's just one of many references out there. There are many free references you can get through your local state departments of health.

MEMBER QUESTION:
Are tick-borne diseases on the rise? If so, is it because of the growth of the deer population?

BENJAMIN:
We are certainly diagnosing more diseases, but that may be due partly to the fact that we're getting better at identifying people with the disease and partly to people being more aware of their risks.

MODERATOR:
Our thanks to Georges Benjamin, MD, executive director of the American Public Health Association, and Virginia Caine, MD, director of the Marion County Health Department for the city of Indianapolis, for sharing their expertise with us today.

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