First brain, spinal infection case of West Nile virus Identified in Weld County

GREELEY, Colo. - Health officials in Weld County have identified four human cases of West Nile virus infection this season.

The victims' ages range from 15 to 81, officials said Friday.  Three of the cases involve West Nile fever but the fourth has been identified as West Nile neuroinvasive disease.

"West Nile neuroinvasive disease is the most serious type of infection, affecting the brain and spinal cord," said Dr. Mark Wallace, Executive Director for the Weld County Health Department.  "The milder viral infection is West Nile fever, in which people experience flu-like symptoms. However, the majority of people who contract West Nile will be asymptomatic, which means they show no symptoms."

According to the county public health department, only a very small number of infected individuals will show the serious symptoms associated with the neuroinvasive disease. Residents who are 65 years old and older are at higher risk for complications, but everyone is at risk for infection, they said.

Health officials recommend the following measures to reduce mosquitoes near homes:

-Drain standing water outside the home, such as water found in pails, old tires, trash cans, and pots.  Use a Mosquito Dunk (larvicide) if you have standing water you cannot drain.
- Avoid over-watering landscapes and yards, because mosquitoes can breed in very small amounts of stagnant water.

Recommendations to prevent mosquito bites include:

- Apply an effective mosquito repellent to exposed skin and clothing.
- Avoid the outdoors from dusk until dawn, when mosquitoes are most active.

Health department monitoring of mosquitoes began in early June through a network of mosquito traps set by Colorado Mosquito Control.  

The Culex mosquito, known to spread West Nile virus, is tested to determine the risk of disease to humans. Currently, mosquito traps in the Johnstown, Milliken and Greeley areas show the highest infection rates for West Nile virus.

There are no medications to treat or vaccines to prevent West Nile infection. Fortunately, most people infected with the virus have no symptoms. About 1 in 5 people who are infected will develop a fever with other symptoms. Less than 1 percent of infected people develop a serious, sometimes fatal, neurologic illness.

If someone develops symptoms, they should contact their health care provider immediately. For more information on West Nile virus and mosquito repellents, visit

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