Dr. Janie Carpenter - Information about the West Nile Virus

The West Nile Virus (WNV) was originally isolated (discovered) in Africa (specifically Uganda) in the 1930's. This virus spreads from one animal to another by mosquitoes (like canine heart worms). In areas of Africa where the virus is endemic (present for a long time and considered "natural" or not a disease threat), 70% of people actually are seropositive (Developed antibodies to the virus as a result of exposure) and show very few clinical signs. The incubation period (the time of exposure until clinical signs) is typical of most viral infections and averages 6 days.

The virus was discovered in the northeastern United States in 1999. By 2001, 27 states had identified the WNV in birds. Birds, especially migrating varieties, play a major role in spreading this virus across the country. Clinical illness, after exposure to the virus, occurs mainly in horses, primates (i.e. humans, monkeys) and certain birds (especially crows, blue jays, raptors).

Dogs and cats do not appear to become ill after exposure. Horses show primarily neurological signs (signs related to brain and spinal cord disease). Birds generally show no clinical signs and recover quickly, except for the crows, blue jays and raptors who develop neurological signs. Humans generally show flu-like illness and recover. Only up to 15% of infected people develop the more severe forms of the disease.

The best way to avoid the WNV is to avoid being bitten by mosquitoes. Use insect repellant on yourself and your family. Do not use the repellant on your dog or cat. Depending on the repellant, these can be toxic to pets and since the WNV is not a disease threat to the dog and cat, do not risk the chance of a severe reaction (to the repellant) in your pet.

Other ways to avoid mosquitoes are to be sure there is no standing water in containers or ditches in your yard (to prevent mosquitoes from multiplying), use fans when outside to circulate the air (mosquitoes are not strong fliers) and avoid the 1 to 2 hours around dawn and dusk when mosquitoes like to feed (the 'buffet" times).

The golden rule for now is to use mosquito repellant when you plan to be outdoors.
- Dr. Janie Carpenter

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