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June, 2003
West Nile Virus Season: What to do?
Sunday Times-Sentinel: Health & Fitness
West Nile Virus season: What to do?
BY Coleen MurphySmith, R.S.
Gallia County Health Dept
The mosquito season
is upon us and West Nile Virus is a growing concern each year. What
was once a disease unknown in the United States has become a part of
our lives during warm weather. What is it all about? What do you need
to know? What is being done? What can you do?
West Nile Virus is a type of virus called a flavivirus that is transmitted through
the bite of an infected mosquito. WNV is not spread person-to-person, or through
contact with birds. It can cause a form of encephalitis in mammals. Predominantly:
humans, birds, and horses. It is common in Africa, West Asia, Eastern Europe, and
the Middle East. It was identified in New York City in 1999 and has spread rapidly
since then. At the end of 2002 West Nile Virus was found to some degree in the entire
contiguous United States except Arizona, Nevada, Oregon, and Utah.
The Centers for Disease Control in Atlanta, Georgia reports that Ohio had 441 human
cases of West Nile Virus illness and 31 deaths in 2002. It is probable that many more
people were infected but showed mild or no symptoms of the disease. Only 20 percent of
people will become ill. Fewer will develop encephalitis or meningitis as a result of
infection. Treatment is supportive only. There is no magic pill. The real key is
prevention.
Mosquito control comes in many forms. Probably the one that most people think of is
the Gallia County Health Department's mosquito spraying program. You may have heard
or seen our pesticide operators in trucks out in the evenings during mosquito season.
We use an ultra-low volume cold mist sprayer. This type of machine uses very small
amounts of a low toxicity pesticide and spreads it out over large areas. In short,
we use the smallest amount of the safest pesticide that has proven to be effective
in our area. This kills the mosquitoes on contact, but is non-residual. That is to
say, it kills the mosquitoes quickly and breaks down quickly so that humans, animals,
and the environment are less likely to be harmed by it. We also treat some bodies of
stagnant water with long-lasting briquettes and pellets. Again, we try to choose the
products that are the most effective and the least likely to harm people, animals, or
the environment.
There are other mosquito control measures that everyone can institute... no licensing
required! Mosquitoes breed in stagnant water, even small amounts can produce thousands
of mosquitoes. Look around your yard for areas where stagnant water lies and eliminate
them. Flower pots, low spots, cans, tires, birdbaths, animal water dishes, toys, wading
pools, and sand boxes. The list is endless. Eliminate these items or their water-holding
ability. Dump excess water out of plants, fill in low spots or holes the dog has dug,
change water in bird baths and animal water dishes every day, cover pools and sandboxes,
dispose of tires or store them in water proof areas. Make sure roof gutters drain properly.
Remind and help your neighbors to eliminate breeding sites. If mosquitoes have nowhere to
breed, well, you won't see many mosquitoes! Don't help them multiply!
Plan activities and yard work before dusk, which is when mosquitoes are most likely to be
biting. If you must be out after dark, wear light-colored clothing that covers you well,
and use DEET-containing insect repellents.
Mosquitoes in this area transmit diseases other than West Nile Virus. St. Louis Encephalitis
and La Crosse Encephalitis, for example. These diseases have been more common than WNV in the
past, but the symptoms are the same. Only laboratory tests can determine the difference. The
same vigilance in mosquito population control and avoidance has been very important in lessening
the occurrence of these diseases. The point is, there are multiple reasons to combat the mosquito
population. Working together, the public and health agencies can have an impact.
For more information, contact the Environmental section of the Gallia County Health Department
at 441-2018.
Mosquito Trivia
How many species of mosquitoes are there?
About 2700.
How fast can a mosquito fly?
Approximately 1 to 1.5 miles per hour.
How far do some mosquitoes fly?
Salt Marsh mosquitoes migrate 75 to 100 miles.
How much does a mosquito weigh?
About 2 to 2.5 milligrams.
How much blood does a mosquito drink per bite?
About 5 millionths of a liter.
How many are resistant to at least one insecticide?
More than 50.
How do mosquitoes find new hosts?
By sight (they observe movement).
By detecting infra-red radiation emitted by warm bodies.
By chemical signs (they are attracted by carbon dioxide and lactic acid, among other chemicals).
How far away can a mosquito smell a potential host?
20 to 35 meters.
What does mosquito saliva and rat poison have in common?
They both contain anti-coagulants: chemicals that prevent blood from clogging.
- Coleen Murphy Smith, R.S.
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