Second Human West Nile Case Confirmed in Washoe County

Threat levels for WNV decreasing with freezing temperatures approaching

October 9, 2019. Reno, Nev. – A second Washoe County resident has tested positive for West Nile Virus (WNV) for 2019, but threat levels are decreasing due to colder weather.

The person infected with WNV went hiking near the meadows of Mt. Rose in mid-August and developed severe symptoms on Sept. 9, 2019. It is suspected that a mosquito carrying WNV may have infected the person during this hike. The person sought medical care within days of developing symptoms and is expected to fully recover.

“The two confirmed cases of residents infected by WNV in 2019 are a reminder of the importance of taking preventive measures to protect against mosquitoes,” Washoe County District Health Officer Kevin Dick said. “Most cases of WNV go undiagnosed. The two confirmed cases are indicative of a significantly larger number of undiagnosed cases that probably have occurred in the community.”

Health District officials urge caution when recreating in areas with mosquitoes, especially during morning and evening hours. Research, however, shows that consecutive nights of freezing temperatures will decimate mosquito larvae, and with decreasing temperatures the ability of mosquitoes to transmit WNV decreases as well. While we are near the end of mosquito season, residents are reminded of the importance of preventive measures when mosquitos are present.

Prevention tips include:

• Wear proper clothing and repellent if going outdoors in the early mornings and evenings
• Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET or other repellents that have been proven by the EPA to be safe and effective. DEET can be used safely on infants 2 months of age and older
• Make sure doors and windows have tight-fitting screens to keep mosquitoes out
• Clear standing water from around homes, including small puddles, pools, planters, as well as plant saucers and pet bowls
• Vaccinate horses for WNV
• Additional prevention tips are available on the CDC Prevent Mosquito Bites webpage

The first human case of WNV occurred Sept. 17, though mosquito samples from Rosewood Lakes and Hidden Valley tested positive in July.

The Health District performed five helicopter larviciding applications in Washoe County in 2019 and conducts other measures to protect the public.

More information on WNV and the Health District’s Vector-Borne Disease Prevention Program can be found here or by calling 775-326-2434.

The Washoe County Health District has jurisdiction over all public health matters in Reno, Sparks, and Washoe County through the policy-making Washoe County District Board of Health. The District consists of five divisions: Administrative Health Services, Air Quality Management, Community and Clinical Health Services, Environmental Health Services and Epidemiology & Public Health Preparedness. To learn more, visit https://www.washoecounty.us/health/