Frisco Stays Ahead of Mosquito PopulationAug 01, 2021 ● By Joshua Baethge
Mosquitoes are a fact of life in North Texas. Few things can kill the fun of a backyard barbecue or pool party more than pesky bug bites. However, as many people are well aware, the bugs are also carriers of the potentially deadly West Nile virus.
According to the Centers for Disease Control and Prevention (CDC), West Nile virus is the leading cause of mosquito-borne disease in the continental U.S. About one in five people infected with the illness will develop a fever and other symptoms including headaches, body aches, joint pains, vomiting, diarrhea or rash. Approximately one out of 150 infected people will develop a more serious, sometimes fatal illness.
To combat the virus, the City of Friso had budgeted $184,800 for mosquito prevention and eradication efforts this year. City staff monitors known mosquito breeding areas year round. In March and April, technicians from the city’s Environmental Health department visit these locations on foot and, if breeding is detected on city property, larvicide will be applied to prevent mosquitoes from maturing to adulthood. If evidence of mosquito breeding is found on private property, the city will contact the property owner and advise them on how to treat the problem.
“There are so many tools that we can use, but the best one is stopping them before they become adults,” City of Frisco Environmental Health Supervisor Julie Fernandez said. “When they become adults, you’re actually behind the curve and now you are combatting a wild insect that is flying around at random.”
Beginning in May, the city deploys 17 separate test pools at sites across the city. These are placed on the ground close to populated areas because the goal is to gauge the situation near where people live. A third-party contractor hired by the city separates captured mosquitoes by gender and species and tests them for West Nile virus. While both male and female mosquitoes can bite, it is females that can transmit the virus to humans.
“The species that we are looking for and reporting on weekly are the Culex species, the ones that are the most known in this area that are endemic to not only carry but transmit the disease readily,” Ms. Fernandez said.
There had been 17 positive West Nile virus tests in mosquitoes collected from eight of the test pool sites in Frisco as of July 16. At that time, there had been no known human cases of the virus in the city. Mosquito testing is scheduled to continue through Nov. 15.
While the number of positive tests is not particularly alarming, Ms. Fernandez said, the potentially troubling fact is that these positives tests came early in the year. Typically, West Nile virus begins showing up later in the summer or early fall.
Also worrisome is the fact that the number of Culex mosquitoes captured jumped significantly in June from the previous month. This has led to some concerns that the area could experience another deadly summer similar to that of 2012. That year, nearly 1,900 West Nile virus cases were reported in Texas – almost double the previous all-time high experienced in 2003. Of those, 48 percent of the cases were concentrated in Dallas, Tarrant, Collin and Denton counties.
According to a CDC report, there were 89 West Nile-related deaths in Texas between May 1 and Dec. 6, 2012. The report also estimated that the statewide financial impact of the outbreak was around $47.6 million, a number that included medical costs, lost productivity and increased mosquito-control efforts.
With the earliness of the positive West Nile findings this year, Ms. Fernandez said, “It’s shaping up to be more like the 2012 season than any season since.”
Unfortunately, there is not an exact reason why West Nile virus season started so early this year. The CDC is conducting research to determine whether factors such as temperature or humidity levels may play a role in the numbers. Similarly, there are questions about why Frisco historically tends to fare better than other area communities when it comes to mosquito issues. It could be due in part to the city’s mitigation efforts, or something as simple as its topography and fewer natural areas of standing water.
To help minimize the impact of mosquitoes, the Frisco City Council adopted an integrated mosquito surveillance and response plan. A copy of the 2013 document can be found on the city’s website, at friscotexas.gov/222/Mosquitoes.
One of the challenges the city faces is determining when to deploy fogger trucks that blanket areas with adulticide, a type of insecticide used against adult mosquitoes. Some residents would like to see the city spray more frequently, while others are more concerned about the use of chemicals than the bugs themselves. Complicating matters is that mosquitoes can adapt over time and become resistant to certain chemicals, rendering them ineffective. To combat that issue, the city’s third-party contractor runs tests every three years to decide whether the chemicals it uses need to be changed.
The city considers multiple factors to determine when to spray adulticide. It is only an option when there is evidence of West Nile virus activity at a level suggesting a high probability of human infection. The city must then decide whether spraying would be an effective tool to deploy. It must also consider
other factors such as weather conditions and the location of the mosquito activity. When the decision to spray is made, the city alerts residents via local media, lighted message boards and other means.
While many people think humans are their target meals, it may be surprising to learn that mosquitoes actually prefer birds. That is why the city focuses much of its fogging efforts on tree lines near homes or riparian areas near creeks and waterways.
Ms. Fernandez said she regularly fields phone calls from residents who want to learn about the risks of adulticide. She wants people to know that adulticide that falls on the ground completely dissipates in sunlight. Also, properly chlorinated pools are not contaminated by the chemicals. Running home air-conditioning or heating units is also not an issue, as the droplets are small and will either disappear or become trapped before they can make it inside of homes.
As for what Frisco residents can do to assist with mosquito-prevention efforts, the Texas Department of State Health Services recommends eliminating standing water around residences, such as in bird baths, clogged gutters and splash blocks stationed at the end of gutter downspouts, and even from saucers that sit beneath potted plants, as stagnant water serves as a breeding ground for mosquitoes.
It is important to remember that the insects typically are most active around dawn and dusk daily. If you can’t avoid being outdoors during those times, wearing long sleeves and pants may reduce the risk of being bitten. Finally, it is strongly recommended that people use an approved insect repellent as an added layer of protection anytime they venture outside.
While it may not be possible to entirely eliminate the threat of mosquitoes and West Nile virus, the efforts of the city, combined with Frisco residents taking proper personal precautions, can go a long way toward significantly reducing the risks.