West Nile Virus Cases Are Rising In Colorado; most cases in 5 years | Local news


Both West Nile virus infections and deaths have increased year over year, and there have been more cases than ever since 2016, according to data from the Colorado Department of Public Health and Environment.

To date, 139 Coloraders have contracted the mosquito-borne disease, which has resulted in six deaths. These numbers are up 297% and 500%, respectively, compared to 2020. In fact, this year’s reported cases are the third highest since 2010, according to the state Ministry of Health.

While COVID-19 has claimed 2,574 lives in Colorado since Oct. 7, and a relatively mild 2020-21 flu season claiming another six lives since Oct. 7, according to CDPHE data, West Nile numbers show there is one more potentially deadly viruses out there and experts say precautions must be taken.

But despite the surge in cases and deaths in West Nile, many health officials said it’s not uncommon for the numbers to fluctuate from year to year, stressing that preventive measures can reduce the likelihood of a contraction.

“It varies from year to year, and it varies geographically,” said Daniel Pastula, associate professor of neurology, medicine, and epidemiology at the University of Colorado School of Medicine and the Colorado School of Public Health. “Some years we don’t have cases, and some years we have a lot of cases.”

The virus was first discovered in a woman in the West Nile District of Uganda in 1937 and identified in birds in the Nile Delta region in 1953, according to the World Health Organization.

The mosquito-borne disease is known to cause fever and headache and, in severe cases, can lead to neuroinvasive disease or death. Still, 80% of those who contract the virus show no symptoms, Pastula said.

About one in 150 people who are bitten by an infected mosquito develop neuroinvasive diseases such as encephalitis, a brain infection, or meningitis. About 10 percent of severely infected people die from the disease, and those who survive may have long-term nervous system problems, according to the U.S. Centers for Disease Control and Prevention.

However, this year, 79 of the cases in Colorado – 57 percent – are categorized as neuroinvasive cases, which is the most since 2013. The greatest risk for severe cases are people over the age of 60 or those with immunosuppressive disorders CDPHE.

The virus resided in the Eastern Hemisphere for decades, but in 1999 it began to find its way across the Atlantic and into America.

Colorado’s first reported case was confirmed in 2002, and the following year the number of cases reached “epidemic levels,” 2,948 confirmed cases, state public health veterinarian Jennifer House said.

“We had what was called an epidemic year in 2003, and at that point pretty much everything in Colorado was naïve to the virus, so there was no immunity at all in our birds, horses, or humans,” House said. “It’s been present in the state since then, and we’ve seen more cases in people every year since our outbreak in 2003.”

Mosquitoes infect the potentially deadly virus from birds and transmit the disease to humans, horses and, in rare cases, pets. Although health professionals know how the insects infect and spread the disease, House said it was impossible to eradicate.

“We can’t eliminate it because it is transmitted by birds and birds migrate, so there is just no way we can eliminate the virus,” House said.

While the virus cannot be eradicated, health officials have come up with several ways to reduce the chances of infection, such as: B. by catching mosquitoes, tests and education.

For example, Larimer County, which reported 17% of the total reported cases in Colorado between 2003 and 2020, has set up over 100 mosquito traps across the county.

Larimer is one of five “hot-spot” counties where infection is most at risk. Boulder, Delta, Mesa, and Weld counties are the others, and the group has combined 53% of all cases in the state since 2003, according to the state.

Every June, Larimer County officials conduct surveillance, monitor mosquito traps and analyze trapped insects, said Kori Wilford, a spokeswoman for the Larimer County Department of Health.

“They’ll look at the mosquitoes and culex mosquitoes that carry West Nile virus and then start testing them and looking for an infection,” Wilford said.

Other methods used in Larimer County vary by county. Loveland regularly sprays from the air, while Fort Collins doesn’t spray until the mosquito count reaches a certain threshold.

Airborne spray, a popular mosquito control method, “minimizes mosquito nuisance and helps stop the spread of mosquito-borne diseases such as the West Nile,” said Wilford.

Other communities like Broomfield County will be entering into contracts with mosquito control agencies to carry out mitigation measures such as aerial spraying.

Spraying, testing and analyzing reduces the number of infected mosquitoes, but does not eradicate 100%. Health officials are also making public service announcements about the virus and have established the “Four D’s”:

  • Drainage: mosquitoes breed in the water. Drain standing water in your yard every week. Bird baths, clogged gutters, and children’s pools are common breeding grounds.
  • Clothing: Wear light, long-sleeved shirts and long pants outdoors. Spray clothing with insect repellent as mosquitoes can puncture clothing.
  • Defended: Apply insect repellent sparingly to exposed skin. Use an approved repellant as per the label. During the busy season, infected mosquitos can be found all over the Front Range, so use repellants where you live, work and relax.
  • Dawn and Dusk: The best way to avoid the West Nile virus is to prevent mosquito bites. Stay indoors, if possible during peak mosquito times – sunset to 1.5 hours after sunset appears to be the most active “feeding time” for the species that transmit the West Nile virus.

These rules should be followed from June through the first frost of the year, House said.

House said she anticipated the number of cases would continue to rise until the first frost.

And while officials know how the virus is spreading and some of the factors that contribute to a “bad year,” House said it was almost impossible to predict how each season will play out.

“There are a lot of factors involved, including the climate, the rain in early spring, stagnant water and then hot, dry summers, so it’s really very complicated,” said House.

Although 80% of those infected with the virus show no symptoms, people should still take the potentially deadly virus seriously, Pastula said.

“You can’t get West Nile unless you are bitten by a mosquito,” Pastula said. “Wear your insect repellent, avoid activities near mosquito areas at dusk and dawn, consider wearing longer pants or sleeves, consider permethrin on your clothing, and stay indoors when mosquitoes are active. “

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