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West Nile Virus


Human West Nile virus infections have been reported in Douglas County. Prevention is key in reducing the spread of West Nile Virus. The following preventive actions are recommended by the U.S. Centers for Disease Control and Prevention (CDC) to reduce individual risk of mosquito-borne illness:

  • Apply an insect repellent containing DEET (N, N-diethyl-meta-toluamide) according to manufacturer’s directions. Repellents containing picaridin and oil of lemon eucalyptus also have some efficacy. However, DEET is the best-studied and most-effective repellent available. Try out different products to see which works best for you. Remember to reapply frequently as needed in heavily mosquito populated areas.

  • Avoid spending time outside when mosquitoes are most active, notably at dusk (the first two hours after sunset) and dawn.

  • Eliminate areas of standing water; including but not limited to bird baths, unmaintained swimming pools and sprinkler runoff, irrigation boxes, pots/buckets all of which support mosquito breeding. Please recheck your property after irrigation or rain storms.

  • Clean stock tanks as often as possible. They are a common breeding place if allowed to collect debris.

  • Make sure doors and windows have tight-fitting screens without tears or holes.

  • Wear pants and long-sleeved shirts, when outdoors.

How It Spreads

West Nile virus most often is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the virus to humans and other animals when they bite. West Nile virus is not spread through casual contact such as touching or kissing a person infected with the virus. 

Severity of Infection

According to the Centers for Disease Control and Prevention (CDC), most people infected with West Nile virus will not develop any type of illness or experience symptoms. It is estimated that 20% of the people who become infected will develop West Nile fever. Symptoms include fever, headache, tiredness, and body aches. 

Approximately one in 150 persons (less than 1%) infected with West Nile virus will develop a more severe form of the disease, West Nile encephalitis or meningitis. Symptoms of the more severe disease include severe headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis and death.


While there is no specific treatment for West Nile virus infection, people who have been exposed to mosquitoes and experience symptoms of the more severe illness are encouraged to contact their health care provider immediately.

Personal Mosquito Sprays

Here are some examples of personal sprays which are considered as effective as "deet".  


  • Repel - Lemon Eucalyptus 40% + p-menthane

  • Cutter Advanced - Picaridin 15%

  • Natrapel - Picaridin 20%


Equine West Nile Virus

Equine West Nile Virus has been reported in the Douglas County area. It is highly recommended that you consult with your veterinarian regarding vaccination for your horses for protection against illness.

Canine Heartworm

Canine heartworm occurs worldwide. It is caused by a filarial nematode transmitted by Aedes and some Culex mosquitoes that can infect domestic dogs, wild canines (e.g., foxes, coyotes, wolves), and cats. The tiny worms migrate through the body to the heart and cause thickening and inflammation of the heart, which can lead to difficulty in breathing, chronic cough, and vomiting, and can sometimes be fatal.  It is highly recommended in this area to contact your veterinarian and follow their recommendations for prevention of heartworm in your pets.

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