Invasive mosquito found in Washington County could carry new viruses

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What do mosquitoes have in common with all that saliva you’ve been coughing up in your COVID-19 test vial? Not a lot. But they are both analyzed for the presence of viruses by the same type of machine, called RT-PCR for reverse transcription-polymerase chain reaction.

This machine is a recent addition to the public health arsenal at Southwest Mosquito and Mosquito Control District (SMACD) and could be useful in response to the alarming discovery in late August of a new type of mosquito invading the Springdale area.

Aedes aegypti is a species of daytime biting mosquito that usually appears in urban areas and can breed quickly in small containers of standing water. It is black with distinctive white stripes. Commonly known as the ‘yellow fever mosquito’, this species is also known to carry the viruses that cause tropical fevers, including Zika, Dengue and Chikungunya, although none of them have yet been. detected in Washington County.

Weeding the garden, adding birdhouses, removing standing water, and using fans and citronella candles are just a few of the eco-friendly ways to keep mosquitoes at bay this season.

The risk is low, but the consequences could be high

The risk of these new viruses appearing in the human population of southwest Utah as a result of this mosquito invasion is, according to Sean Amodt, district administrator at SMACD, quite low. For residents and visitors to Washington County who contract illnesses like Zika, Aedes aegypti should be allowed to breed in a large population and then also pick up and spread these tropical fever viruses by biting already infected humans, possibly travelers from areas where these diseases are prevalent.

But, although the likelihood of a local Zika outbreak is low, the health consequences of these viruses taking hold in the community could be high. Zika, for example, is known to cause joint pain and headaches in adults and brain abnormalities in babies if mothers are infected during pregnancy. Dengue fever can cause headaches, vomiting, muscle aches and rashes, while yellow fever – now rare in North America thanks to the development of a vaccine against it over 80 years ago – devastated human communities and caused hundreds of thousands of deaths in the past.

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In this desert environment, it’s easy to ignore the potential health risks posed by insects that are more commonly associated with humid climates and require bodies of water to reproduce. But deadly mosquito-borne diseases have been an issue for former residents of southwestern Utah that was not resolved until the breeding habitat was managed.

“When the pioneers first arrived here, there were epidemics of malaria until they drained the swamps where the temple is now located,” Amodt said. malaria.

Malaria is transmitted by a kind of mosquito, Anopheles, which Amodt says is still present in the area but is not currently known to be a carrier of the disease. West Nile virus is another more contemporary concern in the region and is transmitted by mosquitoes of the genus Culex.

West Nile human cases surface every summer in southern California, Arizona and the Las Vegas area, making St. George a likely next target, Amodt said. Whenever there is an outbreak nearby, his team receives an increase in calls about biting mosquitoes, which sometimes leads them to find and deal with unexpected newcomers like Aedes aegypti.

A tray of Aedes dorsalis and Culex tarsalis mosquitoes is shown collected in the Salt Lake City Mosquito Control District on Tuesday, July 19, 2016, near Salt Lake City.  Utah health officials are investigating a single case of Zika found in a person caring for a relative who had an unusually high level of the virus in their blood.  It remains a mystery exactly how the disease was transmitted, although the person has since recovered.  (AP Photo / Rick Bowmer)

Intercept the invasion

Amodt wants to stay one step ahead of any potential problems by limiting the local spread of the Aedes aegypti mosquito. Earlier this month, he spoke at a public health advisory meeting where he alerted Springdale residents to the discovery of this species, asked for their help in locating other invaded areas and asked public health officials to keep an eye out for symptoms of tropical fever appearing at local hospitals.

“Traditionally, this whole area of ​​Zion Canyon was quite the habitat of mosquitoes and mosquito control has helped to subside a bit. I hope we can continue on this path, ”Amodt told those gathered for the meeting.

The goal is mosquito control rather than eradication, he explained, because eradication is very difficult and mosquitoes perform certain ecological functions, such as being an important food source for birds and other wildlife. .

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Residents who encounter a biting mosquito during the day in an urban area that fits the description of Aedes aegypti are asked to call the SMACD at 435-627-0076.

Amodt and his team will then visit the area, turn over any containers with unnecessary water and trap the mosquitoes. They will return any mosquitoes collected to the lab for identification and, if they are not among Washington County’s 21 natural species, the SMACD team will return to administer the treatment. Treatment can include adding a bacterial product to water containers that cannot be emptied or spraying with an insecticide mist, usually at night to avoid harming beneficial insects like bees and butterflies.

Related story from 2018 by the author:Global warming infectious Trojan horse: animals moving north may bring new diseases

If a mosquito species known to carry harmful viruses is found, that’s when the district’s new RT-PCR machine kicks in. Mosquito tissue is mixed with a liquid to look like a biological sample much like your COVID-19 saliva vial. They then use an extraction process and a genetic primer to isolate sections of RNA that signal the presence of viruses. These are then replicated using the RT-PCR machine until there are enough copies of this microscopic genetic material to confirm the viral load.

As a special service district funded with just $ 3 in taxes for every $ 100,000 of property value, SMACD sometimes struggles to respond to all possible threats. Recent growth in Washington County has increased their budget, but not as quickly as it has increased the size and complexity of the landscapes they must monitor. That is why Amodt needs as many eyes as possible on this situation.

“The hardest part is we don’t have enough staff to go to all of these areas all the time,” Amodt said. “The best thing that can happen is to have people contact us and then we can focus our energy for a short time in that area and see what’s there.”

Brad Sorensen, left, of the Salt Lake City Mosquito Control District, checks out a decorative pond in the front yard of Miyoung Kim's home on Wednesday in Salt Lake City.  Salt Lake City District Mosquito Control Teams scoured an area of ​​111 square miles, surveying some 700 ponds, 4,000 tree holes, and 17,000 drains.

Mosquito ghosts past and future

The good news is that southern Utah has a history of successfully suppressing a Aedes aegypti uprising. Eight years ago, the species made an appearance in Washington County. Fortunately, both its distinctive, aggressive, diurnal biting style and its short 100-meter range facilitated the identification and containment of SMACD.

“In 2013, we met some of these [Aedes aegypti] for the first time in this area, ”said Amodt. “It was just in a very secluded RV park area, so we were able to easily walk through the area and root out any potential places they would breed or lay their eggs. These are containers that breed mosquitoes, so every dog ​​dish, every bucket that could hold water, we just turn them over and take care of. “

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This year, extreme flooding in late July and early August across southwestern Utah could make it more difficult to clear out any receptacles of standing water where these mosquitoes could breed. And these types of flooding could become more frequent in the years to come.

Climate change was recently determined by the scientists who wrote the latest report of the Intergovernmental Panel on Climate Change (IPCC) be the cause of an increase in severe weather events such as intense torrential rains that dumped large amounts of water over small areas of Zion National Park and Enoch this summer.

Following:Young people in Utah search for answers to a question about climate change, National climate reporter

Climate change can also make future mosquito control more difficult by making it easier to move species to new habitats. Amodt believes this latest invasion is likely due to tourists unknowingly carrying mosquitoes to the area in their cars or even as eggs in the mud on their tires, as St. George was already hot for them. mosquitoes. But scientists have already warned that rising average global temperatures allow vectors of animal diseases like mosquitoes to introduce viruses to new areas as they expand their range.

These factors could complicate Amodt’s work in the future. But for now, he’s just going to take one invasion at a time.

“The next best thing [to mosquito control and treatment] is Mother Nature. Just pray for a cold winter and I hope it will take care of them, ”Amodt said.

K. Sophie Will contributed to this report.

Joan Meiners is the environmental reporter for The Spectrum & Daily News as part of The Ground Truth Project’s Report for America initiative. Support his work by make a donation to these nonprofit programs today. To follow Jeanne on Twitter at @beecycles or email him at [email protected]



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