BOULDER COUNTY, Colo. — A second Colorado resident has contracted West Nile Virus (WNV), Boulder County Public Health (BCPH) confirmed.
BCPH said the Boulder resident in their 70s, who has been hospitalized with meningitis, reported being bit by multiple mosquitoes while spending extensive time gardening in their backyard.
The virus is transmitted to humans from the bite of an infected mosquito. While most infections are mild, more serious infections can cause inflammation of the brain and/or meningitis, loss of vision, paralysis, coma, tremors, convulsions and death, said BCPH.
> Video above: Becky Ditchfield says she doesn't want her grandma to be remembered just as a West Nile statistic.
Colorado's health department reported the state's first case of West Nile Virus this year on Aug. 14.
The Colorado Department of Public Health and Environment (CDPHE) said that case was in a person who lives in Delta County.
Mosquitoes collected from three sites in Weld County tested positive for the virus, according to the Weld County Health Department (WCHD).
They were collected Aug. 3 and Aug. 10 from the Johnstown, Milliken and Platteville areas as part of the county's West Nile Virus surveillance program.
The first instance of the virus this year in Weld County was found in traps on the east side of the Town of Berthoud during the week of July 27. The identification of infected mosquitoes was slightly delayed, as the state lab was also meeting the demands of COVID-19 testing.
“Finding WNV-positive mosquitoes is no surprise for this time of year, with the hotter temperatures we’ve had in July and August,” said Dan Joseph, director of the Environmental Health Services Division. “We are also seeing above average number of Culex mosquitoes (the mosquitoes known to transmit WNV) for the first time this summer.”
Mosquitoes in Superior, Louisville and Longmont have also tested positive for the virus.
BCPH confirmed on Aug. 18 that the positive mosquito pools came from traps near Coal Creek Golf Course and Coal Creek Trail in Louisville, Original Town in Superior, and Izaak Walton Park and St. Vrain Greenway in Longmont.
The vector index, which describes the relative risk of West Nile Virus transmission, is 0.21 for Zone 3 (Superior and Louisville combined) and 0.20 for Zone 2 (Longmont). Emergency spraying may be recommended when the vector index reaches 0.75 or higher, according to BCPH.
“Even though it can be inconvenient, taking steps to protect ourselves and loved ones is the best thing we can all do to prevent becoming very ill,” said Marshall Lipps, Boulder County Public Health environmental health specialist. “Our recent high temperatures and standing water have created the ideal environment for mosquitos to breed."
Weekly mosquito testing for the virus began statewide in June, CDPHE said. Counties or municipalities trap adult mosquitoes, and labs test them, providing an estimate of the number that are infected. The results help pinpoint the risk to humans in the area. This year, West Nile virus-positive mosquitoes have been found in Larimer, Delta and Weld counties.
CDPHE said not all counties and municipalities test mosquitoes, so it’s important for all Coloradans to take steps to protect themselves throughout the summer.
Most human West Nile Virus cases are reported in August and September. Colorado had 122 reported human cases in 2019, including eight deaths.
Most people who are infected don’t have symptoms, CDPHE said. About 20% of infected people have flu-like symptoms, and fewer than 1% develop a serious, potentially deadly illness. People over age 60 and those with certain medical conditions are at greater risk of serious illness. See a health care provider if you develop severe headaches or confusion.
To protect yourself:
- Use insect repellents when you go outdoors. Repellents containing DEET, picaridin, IR3535, and some oil of lemon eucalyptus, and para-menthane-diol products provide the best protection. Follow label instructions.
- Limit outdoor activities at dusk and dawn, when mosquitoes that carry West Nile Virus are most active.
- Wear protective clothing (long pants, long-sleeved shirts and socks) in areas where mosquitoes are active. Spray clothes with insect repellent for extra protection.
To mosquito-proof your home:
- Drain standing water around your house often. Empty water from tires, cans, flowerpots, clogged gutters, rain barrels, birdbaths, toys, and puddles.
- Install or repair screens on windows and doors.
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