West Nile Virus Illness

WNV is spread by the bite of an infected mosquito. While the virus has been spread through blood transfusions and organ transplants, it’s extremely rare. New tests are in place to prevent this rare type of transmission.

WNV cannot be spread through casual or intimate contact, such as touching or kissing a person with the virus.

Risks to Pets

WNV infections have been documented in many household pets, as well as larger domestic animals, such as horses. In general, household pets have not developed illness as regularly as humans have. However, horses have developed severe and life threatening complications when infected with WNV.

WNV testing can be provided by your primary health care provider or a community health center. Unfortunately, Boulder County Public Health does not currently have the ability to provide these testing services.

Testing Recommendations

WNV tests are available to health care providers to help diagnose patients that have symptoms. However, when these tests are used on people that do not have symptoms, there is an increased chance of having false or inaccurate results. Thus, being testing when there are no signs of illness may provide misleading results.

If you are experiencing symptoms consistent with WNV infection, including fever, extreme fatigue, head and body aches, skin rashes, and/or swollen lymph glands, you should consult with your health care provider for appropriate evaluation and testing.

As of now, the best treatment available for West Nile virus is prevention. No specific treatment is available at this time for West Nile virus. Individual symptoms, however, may be treated accordingly.

If you feel that you have been infected with West Nile virus, contact your health care provider. If you suffer any severe symptoms, such as unusually severe headaches, confusion, disorientation, or paralysis, seek medical attention immediately.

While WNV can strike even the healthiest of Boulder County residents, it can be easily prevented. Remember the 4 Ds:

• DEET – use DEET- enhanced insect repellant (a 2% soy-based product is also available).
• Dress – dress in long sleeves and pants.
• Dusk to Dawn – avoid the outdoors from dusk until dawn.
• Drain – drain standing water outside your home.

Learn more about WNV prevention.

Higher Elevations

There is some speculation that the mosquitoes primarily responsible for WNV transmission may not be present in large numbers at altitudes above 8,000 feet. However, until more is learned about the mosquito populations at higher altitudes, the best recommendation is to protect yourself at all altitudes.

Immunity

It is likely that infection will provide immunity against being re-infected later in life. However, the immunity may wane over time and precautions against mosquito exposures are always recommended (follow the 4D's).

In addition, there are two other mosquito-borne illnesses that have been seen in Colorado in the past; St. Louis Encephalitis and Western Equine Encephalitis. Because of these other viruses, public health officials continue to recommend following the 4D's, regardless of your WNV infection history. 

1 out of 5 people infected with WNV will suffer a debilitating illness that will often last longer than one week, and in some cases, more than three months. Symptoms typically develop  between 3 and 14 days after being bitten by an infected mosquito. Symptoms include:

• fever
• extreme fatigue
• head and body aches
• skin rashes
• swollen lymph glands

Severe symptoms include: 

• meningitis
• encephalitis
• loss of vision
• paralysis
• coma
• tremors
• convulsions