West Nile Virus in Fort Collins

mosquito west nile virus
Source: NBC


For the first time this year, the West Nile virus has been detected in Fort Collins. Mosquitoes infected with the virus have been found in southeast in northeast Fort Collins, which was announced Tuesday by city officials. There still hasn’t been any logged cases of humans with the virus this season. The detection of the infected mosquitoes still isn’t enough to start mosquito spraying.

In order to keep yourself safe from the virus, here’s what you should know about the infected mosquitoes and mosquito spraying in Larimer County.


1. Fort Collins has higher standards than other municipalities for spraying.

In order for the spraying of to occur, the measurement of the infected mosquiteos has to reach the vector index of 0.75 in one of the four city zones. The current index is only 0.2 and the city will not begin spraying until two human cases are confirmed within one week.

Other cities in Northern Colorado, however, will spray based on a lower vector index or on the number of mosquitoes alone. Timnath plans to spray this week while Loveland has already sprayed several times in the past month.

2. There have been no human cases of West Nile virus confirmed in Larimer County in 2017.

The West Nile virus usually begins showing in late June and tends to last through the first freeze. Human infections peak in September because the infections can take a few weeks to confirm. Larimer County has been ranked as one of the top counties in the nation for West Nile Virus. The county recorded 14 cases last season with Weld County just behind with 12 cases.

There has only been one human case confirmed and publicly announced with West Nile virus in Jefferson County. As of June 30, the unidentified resident was recovering at home.

3. Sign up for spray notifications.

Stay up-to-date on spraying by signing up for notifications from the county and city of Fort Collins. Larimer County has to step in last year to spray in the city when they didn’t meet the thresholds.

You can sign up for the spray notifications at fcgov.com/westnile/wnv-subscribe.php for Fort Collins and larimer.org/subscriptions.cfm for all of Larimer County.

Avoid the Bite

  • Stagnant water is a breeding ground for mosquitoes; drain all stagnant water from your backyard/neighborhood. If applicable, cover and seal any rain barrels.
  • While outside, dress in long sleeves and pants. Also consider using insect repellent on your clothing for safety.
  • If using insect repellent, make sure it is at least 10% DEET
  • Mosquitoes are most active during dusk and dawn. Try staying inside during this period of time.