WEST NILE VIRUS

From Dr. David Kersting, DVM

One of five viruses in the United States that attacks and damages nerve cells in the brain, spinal cord and peripheral nerves. Similar viruses are the St. Louis Encephalitic Virus, Eastern Equine Encephalitis and Western Equine Encephalitis Viruses. These five viruses are usually described as causing meningitis and encephalitis or inflammation of the brain and surrounding membranes. These viruses are passed from one individual to another by a mosquito bite. The mosquito must bite an infected individual, drawing blood and virus into the mosquito's body and then the mosquito injects the virus into the next individual it bites. The West Nile Virus has been known to the world since 1937 but entered the United States through New York in 1999. First, birds began to die of the virus in large numbers. As the virus population increased, mosquitoes not only passed the virus from one bird to the next, but also from birds to people and other mammals.

Eighty percent of people who are exposed to the virus mount a successful immune response, killing the virus, and do not develop symptoms. The remaining twenty percent develop mild symptoms in 3 to 15 days of fever, headache, body aches, skin rash and swollen lymph nodes. The individuals most at risk are people with low immune systems such as the elderly. With a compromised immune system, "flu-like" symptoms progress into muscle weakness, stiff neck, stupor, disorientation, tremors, convulsions, paralysis, coma and death. In previous years, across the world, similar illnesses also occurred in birds and mammals (including the horse). Now in the U.S., this strain of virus is causing much more illness and death in birds, especially crows, blue jays and raptors. Symptoms develop in a higher percentage of birds one to seven days after being bitten. A bird develops depression, weakness, circling, ataxia, change in posture and vision problems and frequently death.

Statistics include:

1999 - twelve people develop symptoms and seven die.

2000 - eighteen people develop symptoms and one dies.

4000 birds from 12 states die.

New York City - 176 birds die.

- 129 are crows

- 1 macaw found dead in Central Park

- 1 cockatiel in a 6th floor apartment dies. The cage mate never developed symptoms. Both birds have not left the apartment in over one year.

- 2 cockatiels found dead outdoors in the state of New York.

- 1 cockatiel found dead outdoors in New Jersey.

2001 - The virus has been identified in 23 states including St. Louis, Missouri.

There is no medication to kill the virus. Treatment is to support the patient's body until their own immune system kills the virus. There is no vaccine available for birds or people. A vaccine has been issued to use in horses under a one-year conditional license. Recommendations are to stay calm and keep pet birds indoors at dawn and dusk when mosquitoes are active. Check the integrity of all screens. Use mosquito netting to keep mosquitoes out. Use insect repellent and wear shoes, socks, long pants and long sleeved shirts. Eliminate breeding areas for mosquitoes. Please call us with any questions. We believe this is a very low risk disease for our pet birds and us. For current information go to www.nwhc.usgs.gov/