First West Nile virus case confirmed in Denver in 2024 – authorities urge caution

DENVER – Denver on Friday reported the first known human case of West Nile virus in a resident in 2024, while health officials urged residents to take precautions to avoid contracting the potentially deadly disease.

Officials with the Denver Department of Public Health and Environment (DDPHE) said in a news release that intervention specialists confirmed the first human case in a Denver resident, but did not provide further details about the case.

The Denver case is the 14th human case reported statewide this year. Additional cases have been reported in Arapahoe, Delta, Jefferson, Kit Carson, La Plata, Larimer, Mesa and Weld counties. Arapahoe County has the most cases of West Nile virus so far and was the first to report a human case this year, marking an early start to the West Nile virus season in Colorado.

Last year, 634 cases of West Nile virus were reported in nearly two-thirds of Colorado's counties – the highest number of cases in 20 years, according to state data. More than 50 people died and nearly 400 were hospitalized because of the disease.

While most people infected with West Nile virus do not show symptoms, some can become seriously ill and even die, according to the Colorado Department of Public Health and Environment (CDPHE). People age 60 and older and those with certain medical conditions are at higher risk of severe illness, officials said.

How to protect yourself and your family from the West Nile virus

Mosquitoes are most active at dawn and dusk, so health experts say the first line of defense against possible infection is to avoid activities during these times.

As mosquito season continues, health officials recommend the following steps to protect yourself and your family from West Nile virus:

• Prevent mosquitoes from laying their eggs in or near water on your property by:
  • Eliminate sources of standing water near your home by emptying, scrubbing, turning over, covering, or throwing away items that hold water, such as tires, buckets, planters, toys, wheelbarrows, pools, birdbaths, flower pots, or garbage containers once a week. All of these items can become breeding grounds for the mosquitoes that carry West Nile virus.
  • Look for water containers indoors and outdoors
  • Avoid watering on concrete or on the street, as puddles can form there, which can become a breeding ground for mosquito larvae.
  • When making landscaping decisions, consider ways to minimize overspray (from irrigation) onto roads and into gutters.
• Wear long pants, long-sleeved shirts and socks in areas where mosquitoes are active
• Use an insect repellent that contains DEET, picaridin, lemon eucalyptus oil, or paramenthanediol. The EPA has a database where you can search and find a repellent that works for you.

In addition to protecting your home from standing water around your house on a weekly basis, you can also do so by installing or repairing fly screens on windows and doors.

How to recognize an infection with the West Nile virus

Symptoms of West Nile virus infection appear two to 14 days after infection. 1 in 5 people experience fever, body aches, headache, vomiting, diarrhea, joint pain, weakness, and occasionally skin rashes and swollen nymph nodes.

While most people infected with West Nile virus do not experience symptoms, according to the DDPHE, about 1% of those infected may develop severe, sometimes fatal, neuroinvasive disease that can lead to encephalitis (inflammation of the brain) and/or meningitis (inflammation of the meninges), loss of vision, paralysis, coma, tremors, convulsions, and even death.

If you experience these symptoms, you should talk to your doctor, especially if a fever occurs after a mosquito bite, along with severe headache or confusion.

While there is no treatment, cure or vaccine to protect against West Nile virus, doctors can treat symptoms to help patients feel better and possibly recover faster, Denver health officials said.

In Colorado, most West Nile virus cases are diagnosed in August and September, but cases can be detected as early as May and as late as December. In general, mosquito season lasts from late April to mid-October, with the end usually signaled by the first frost in the fall.