It was September 2018, and Vandenberg, then 67, had been feeling a little “under the weather” for a few days, like he had the flu, he said.
He developed inflammation of the brain. He lost the ability to read and write. His arms and legs were numb from paralysis.
Although this summer saw the first local infection in two decades of another mosquito-related disease, malaria, it is West Nile virus and the mosquitoes that spread it that are most worrying federal health officials.
Roxanne Connelly, a medical entomologist at the Centers for Disease Control and Prevention (CDC), said the insects, a species of mosquito called Culex, are for the Centers for Disease Control and Prevention (CDC) “the most concerning issue currently in the continental United States “
This year’s unusually wet season due to rain and melting snow, combined with intense heat, appears to have led to a surge in mosquito populations.
And according to CDC scientists, these mosquitoes are becoming increasingly resistant to the pesticides found in many sprays used by the public to kill mosquitoes and their eggs.
“That’s not a good sign,” Connelly said. “We are losing some of the tools we typically use to control infested mosquitoes.”
At the Centers for Disease Control and Prevention’s Insect Laboratory in Fort Collins, Colorado, home to tens of thousands of mosquitoes, Connelly’s team found that Culex mosquitoes lived longer after exposure to insecticides.
“You want a product that confuses them, not does it,” Connelly said, pointing to a bottle of mosquitoes exposed to the chemicals. Many people still fly.
Laboratory experiments have found no resistance to insecticides commonly used by people to repel mosquitoes while hiking and other outdoor activities. Connelly said they continue to do well.
But as insects become more powerful than pesticides, their numbers are soaring in some parts of the country.
As of 2023, there have been 69 human cases of West Nile virus infection reported in the United States, according to the Centers for Disease Control and Prevention. This is far from a record: in 2003, 9,862 cases were recorded.
But two decades later, more mosquitoes mean a greater chance that people will get bitten and get sick. Cases in West Nile typically peak in August and September.
“This is just the beginning of how we will see West Nile begin to develop in the United States,” said Dr. Erin Staples, a medical epidemiologist at the Centers for Disease Control and Prevention laboratory in Fort Collins. “We expect cases to steadily increase over the next few weeks.
For example, 149 mosquito traps in Maricopa County, Arizona, tested positive for West Nile virus this year, compared with eight in 2022.
John Townsend, vector control manager for Maricopa County Environmental Services, said standing water from heavy rains combined with extreme heat appears to be making the situation worse.
“The water there is just ripe for mosquitoes to lay eggs in,” Townsend said. “Mosquitoes hatch faster in warm water – within three to four days, compared to two weeks in cooler water,” he said.
An unusually wet June in Larimer County, Colorado, where the Fort Collins lab is located, also resulted in an “unprecedented abundance” of mosquitoes that can transmit the West Nile virus, said Tom Gonzalez, the county’s public health director.
County data shows there are five times more mosquitoes in West Nile this year than last year.
Connelly said economic growth in some parts of the country is “very concerning.” “It’s different from what we’ve seen in the last few years.”
Since West Nile virus was first discovered in the United States in 1999, it has become the most common mosquito-borne disease in the country. Staples said thousands of people become infected every year.
West Nile is not spread from person to person through casual contact. The virus is only transmitted by Culex mosquitoes. These insects become infected when they bite sick birds and then transmit the virus to humans through another bite.
Most people never feel anything. According to the CDC, one in five people experience fever, headache, body aches, vomiting and diarrhea. Symptoms usually appear 3–14 days after the bite.
One in 150 people infected with West Nile virus develop serious complications, including death. Anyone can become seriously ill, but Staples said people over 60 and people with underlying health conditions are at higher risk.
Five years after being diagnosed with West Nile, Vandenberg has regained many of his abilities through intensive physical therapy. However, his legs continued to go numb, forcing him to rely on crutches.
When Vandenberg collapsed that morning in September 2018, he was on his way to the funeral of a friend who had died from complications from West Nile virus.
The disease “can be very, very serious and people need to know that. It can change your life,” he said.
While resistance to pesticides may be on the rise, Connolly’s team found that the common repellents people use outdoors are still effective. According to the Centers for Disease Control and Prevention (CDC), it is best to use pesticides that contain ingredients such as DEET and picaridin.
Post time: Mar-27-2024