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First human cases of West Nile virus this season emerge in Larimer County, Delta County

Colorado has had cases of West Nile virus every year since 2002
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For the first time this season, four people have tested positive for the West Nile virus in Colorado.

The cases are out of Larimer County, Weld County and Delta County, according to the Colorado Department of Public Health and Environment (CDPHE).

The infected individuals from Larimer County and Delta County were recovering from the illnesses as of Friday morning. Weld County said its one of its patients was currently hospitalized with a serious neuroinvasive disease and the other was recovering at home from febrile illness.

Colorado has had cases of the West Nile virus every year since 2002, according to the CDPHE. In 2020, Colorado reported 35 human cases and one death. The cases are most often reported each year in August and September.

This year, mosquitoes in several Colorado counties have tested positive for the West Nile virus, including those found in Adams, Boulder, Delta, Denver, Larimer, and Weld counties. The virus is most commonly spread to a person via mosquito bite. It cannot be spread person to person.

Most people who become infected do not show symptoms, but about 20% of cases include flu-like symptoms. Fewer than 1% of infected people have a more serious reaction, according to the CDPHE.

People who are over the age of 60 and have certain medical conditions such as cancer, diabetes, hypertension and kidney disease, and people who have received organ transplants, are at greater risk for a serious illness, according to the CDPHE.

Dr. Jennifer House, deputy state epidemiologist and public health veterinarian, said residents and visitors can take simple precautions to protect themselves.

“Use an effective insect repellent, wear protective clothing, or stay indoors when mosquitoes are active, and mosquito-proof your home," House said.

Repellents that contain DEET, picaridin, IR3535, and some oil of lemon eucalyptus and para-menthane-diol products provide the best protection, CDPHE said.

To keep mosquitoes away from your home, drain or get rid of nearby standing water and use screens on windows and doors.