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West Nile virus confirmed in Utah resident; Officials encourage mosquito bite prevention

Posted at 9:09 AM, Sep 02, 2022
and last updated 2022-09-02 19:34:27-04

SALT LAKE CITY — Officials are encouraging Utahns to protect themselves from mosquito bites after the first human case of West Nile virus was confirmed in the state for 2022.

The infected person is a male between the ages of 65 and 84 and is a resident of the Weber-Morgan Health district, the Utah Department of Health and Human Services said.

He was hospitalized with a severe case and is now recovering.

In addition to the first man, two other human cases are being investigated for West Nile Virus in Weber and Uintah counties.

The human case comes about a month after health officials detected the virus in mosquito pools throughout Utah. State officials say as of Thursday, 73 positive mosquito pools have been identified in Davis, Salt Lake, Tooele and Uintah counties.

In 2021, 28 human cases of West Nile Virus were reported in Utah and three people died.

“We expect we’ll unfortunately continue to see human cases get reported and confirmed through about November,” said Rettler. “Usually the human cases, we’ll get a little bit later. Since the mosquitoes wrap up around November, we might see human cases to the end of November.”

Rettler adds that about 70 to 80 percent of people don’t develop symptoms of West Nile and won’t even know they have it. About 20 percent might have flu-like symptoms and may not even need to be hospitalized. And less than one percent could develop neuroinvasive West Nile, which means the virus infects the brain or spine.

“We’ve been actually very fortunate this year in that we’re not seeing a lot of positive virus activity within our mosquito specimens,” said Ary Faraji, the executive director and entomologist for the Salt Lake City Mosquito Abatement District.

Faraji’s team searches for and studies mosquitoes in the area and works to control the spread by mostly targeting water bodies with breeding mosquitoes and kill the larva before they grow into adults.

“So we are routinely collecting mosquitos, we are in numerating them to see how many species are present, at what location at what point in time, and then most importantly, we try to determine their species composition and then we also test them for the presence of pathogens to intervene with appropriate control measures,” said Faraji.

The Health Department says they found the first mosquitoes carrying West Nile virus a month before the first human case, which is pretty standard, but the positivity rates are not cause for alarm yet.

“As far as virus activity, for one reason or another, it’s been at a minimum within our mosquito populations, which is quite perplexing for us, but it’s not out of the ordinary because this process of virus transmission and mosquito activity is so dynamic, and nobody knows what's going to happen from season to the next,” added Faraji.

Some areas are more prone to having mosquitoes that can spread the West Nile virus.

“We know that the areas that are the hottest spots this year and have historically been the hottest spots are in Salt Lake and Davis. Uinta is seeing a little bit higher of the year, so those are the areas that there's the most West Nile activity, really high mosquito activity as well,” added Rettler.

“Naturally, these pathogens are maintained between mosquitoes and birds, that’s the natural cycle. But Culex Tarsalis is on a bridge vector — that’s a mosquito that loves to bite birds, but also loves to bite mammals including us as humans,” said Faraji. “So we’re extremely concerned about that type of mosquito because it can feed on a bird, pick up a pathogen, and for its next meal, it may be feeding on a human host or equine host.”

Officials encourage Utahns to protect themselves against mosquito bites by using insect repellent, limit outdoor time from dusk to dawn - which is when mosquitoes are most active and wear protective clothing like long pants and socks.

To limit mosquito presence around the home, experts say to limit standing water that is outside including water from pet dishes, flower pots, ponds, buckets, tarps and tires.