With all the current events this year about animal-related diseases and their affect on humans, be thankful this fall that you have only heard a little bit about the West Nile Virus. If we had a hurricane or more rainfall this summer and fall, the mosquito population would probably have resulted in your knowing a lot more about this virus than you do right now. That is because mosquitoes play a major role in how the disease is spread.

West Nile Virus has been increasingly found this year in North Carolina and the eastern half of the United States. It is spreading. Each week, it seems, new reports are released. Wild birds like crows and blue jays have been found dead with the virus. Chickens are regularly put out across the state in cages and then blood tested to see if they get the disease from mosquitoes. This month, a couple of chickens did test positive for the West Nile Virus. This indicates further spread of the disease. A few North Carolina horses have also gotten the virus from mosquitoes.

The threat to humans in the United States first arrived in New York City in the summer of 1999. Nine of 83 people known to be infected with the West Nile Virus died. Several birds and horses were also infected. The virus moved down the coast and inland so now about half the states has had at least one case of the virus.

Both birds and mosquitoes are needed to spread the virus. Birds hold the virus, and when bitten by a mosquito, the insect gives the virus to other birds, animals, or humans. Many different mammals have been found to be possibly infected, but horses are the most common. About one-third of the 25 New York horses known to be infected with the West Nile Virus died.

If even noticed, the virus most commonly causes mild flu-like symptoms that can be confused with many different types of infections. More severe symptoms are related to encephalitis (swelling of the brain). Infected animals and people may have tremors and other nervous system-type symptoms. Less than one percent of humans bitten by infected mosquitoes will become seriously ill. The young and the old are most susceptible.

Less than one percent of the mosquito population is infected and can transmit the West Nile Virus. Mostly wild birds carry and harbor the disease. In a wet and bad year for mosquitoes, the virus could be more easily spread. An infected bird does not naturally infect another bird, horse, human, or other mammal. The mosquitoes take the virus from an infected bird to another animal. An infected horse or human does not infect another horse or human.

Since mosquitoes play such an important part in the spread of the West Nile Virus, we should do all we can to reduce the mosquito population. Standing water and breeding sites for mosquitoes should be eliminated. We should also use personal insect repellants.

There is an unknown potential to affect livestock and poultry. A conditional license was issued this summer for a horse vaccine. Each state has to approve the vaccination.

Wild birds are thought to have brought the virus to New York over two years ago. The virus is known to have been around Asia, Africa, and the Mediterranean region since the 1930s.

To monitor the spread of the virus, the public is asked to report dead birds, especially crows and blue jays. Odd-acting or recently dead birds can be reported to the North Carolina Public Health Pest Management Section at 1-877-790-1747 or by E-mail at NCWNV@NCmail.net. More reporting information is at the North Carolina Department of Environment and Natural Resources website:

For other information on the West Nile Virus and mosquitoes visit the following websites:

E-mail address: James_Cochran@ncsu.edu

Mailing Address:
P. O. Box 2280
Lumberton, NC 28359-2280

Phone: 910-671-3276
Fax: 910-671-6278

Date Created 10/26/01
Last Updated 1/28/04