West Nile Virus

West Nile virus is a reportable disease in Oklahoma.  West Nile virus was first identified in the United States in the New York City area during the Summer of 1999. Previously, this mosquito-borne virus had only been found in parts of Africa, Asia, Europe and the Middle East. The introduction of this foreign virus was recognized by deaths of thousands of birds (particularly crows and jays) and an epidemic of encephalitis in people and horses. Over the next few years, the virus rapidly expanded its geographic range. Since national surveillance for this disease began in 1999, there have been a total of 28,961 human cases with 1,130 deaths reported to the Centers for Disease Control and Prevention (CDC) by 46 states through the ArboNet system.

From 7 years of experience tracking West Nile virus in Oklahoma, we have learned that the West Nile virus season consists of the months of May to November. Persons are at greatest risk of exposure to infected mosquitoes from July through October in our state. Persons of any age can develop symptoms of disease after being bitten by an infected mosquito, but those over the age of 50 are at greater risk of developing serious illness of the nervous system.  During Oklahoma's 7 year experience with West Nile virus, 318 confirmed cases of human disease have been reported; many cases required lengthy hospital stays and 20 Oklahomans have died from this virus.

The Oklahoma State Department of Health advises use of insect repellants-- particularly those containing DEET, picaridin, oil of lemon eucalyptus [p-menthane 3,8-diol (PMD) or IR 3535] -- when enjoying outdoor activities like gardening, yard work, camping, or other leisure activities. The type of mosquitoes that transmit West Nile virus are most active during evening and early morning hours, so it is most important to take mosquito bite precautions during that time of the day. It is also recommended to drain or treat standing water around your home with a mosquito larvacide to reduce mosquito breeding sites.

West Nile virus Fact Sheets and Information:
West Nile Virus Fact Sheet (53k.pdf)
   Virus del Nilo Occidental Hoja Informativa (48k.pdf)
West Nile Virus Questions and Answers
Pet Owner Questions and Answers
Insect Repellent Use and Safety
Wild Bird Testing
Mosquito Protection Fact Sheet (109k.pdf)
Mosquito Repellent Fact Sheet (66k.pdf)
Mosquitoborne Disease Prevention Tips

West Nile virus Healthcare Provider Resources:
Physician Instructions for Testing

West NIle virus Surveillance Data and Statistics:
Current Weekly West Nile Virus Surveillance Report (32k.pdf)
West Nile Virus 2008 Surveillance Summary (30k.pdf)
West Nile Virus Cases by Month, 2008 (11k.pdf)
West Nile Virus Cases by Year, 2004-2008 (11k.pdf)
West Nile Virus Cases by Week of Onset, 2007-2008 (15k.pdf)
West Nile Virus Cases and Deaths by Year, 2002-2008 (7k.pdf)
West Nile Virus Incidence Rate by Year, 2004-2008 (11k.pdf)
Map of Human, Equine and Mosquito WNV Activity, 2008 (29k.pdf)

External West Nile virus Resources:
CDC West Nile Virus Page
Kid'sHealth West Nile Virus Info
CDC - West Nile Virus Blood Transfusion Questions & Answers
CDC - Arboviral Encephalitides
USDA - West Nile Info
The National Pesticide Information Center - West Nile Virus
National Biological Information Infrastructure
OSU Entomology Department
EPA Mosquito Control
American College of Physicians West Nile Virus Education Resource
National USGS West Nile Activity Map