West Nile virus cases double in Tarrant County … and the season isn’t over
With so much attention focused on COVID-19 over the past few years, it's easy enough to lose focus on another pesky, if less dangerous, virus — that of the West Nile variety.
Though the disease was first discovered in the West Nile District of Uganda back in 1939, it is now pervasive in Texas and the rest of the U.S. The state's two hottest West Nile infection areas are in and around Houston and the Metroplex. Lucky us.
It's close to home, too — sometimes too close: The first reported sampling of infected mosquitos in Tarrant County this year happened to be in Arlington.
Some background: West Nile first showed up in this country in 1999, probably brought into the U.S. by an infected bird. It then spread across the country via an endless bird-mosquito cycle. The mosquito ingests the blood of an infected bird, most commonly a crow or blue jay, which was infected in the first place by a virus-carrying mosquito.
One of those mosquitos then bites a person, with mixed results . Around 80 percent of those bitten are either asymptomatic — they show no symptoms — or their reaction is so mild that they never realize they have the disease and recover without issues.
The other 20 percent of those infected are not so fortunate. The virus may become neuroinvasive, a result often involving hospitalization, intravenous fluids, respiratory support and secondary infections. On rare occasions, death results. No vaccine is available for humans. As is the case with COVID-19, elderly people or individuals with other health issues are most vulnerable. West Nile tends to be seasonal, with a direct correlation to mosquito populations, running from April to November.
Recovery from the disease may take a month or more.
Which brings up a question: How concerned about the West Nile virus should residents be?
"I would place this high on the priority list for elderly citizens and citizens that have compromised immune systems because those are the people that are most at risk of the more severe form of West Nile virus, [the] neuroinvasive form," said Arlington Health Services Manager Aimee Rockhill-Carpenter.
It's easy enough to calculate why Houston, still recovering from flooding problems and standing stagnant water related to a hurricane passing through, would end up with a mosquito explosion. But why would this be true in an area like DFW, which has been in a semi-drought most of this mosquito breeding season?
"We're constantly trying to educate people because, in urban, dense populations, people are their own worst enemy, with mosquitoes breeding on their own property and neighborhoods," Rockhill-Carpenter said. "Part of our public health outreach is explaining to people about cleaning out your rain gutters, cleaning out your French drains, applying Bti in your French drains, not having standing water in plant saucers or birdbaths or boats without covers or tarps that hold water."
Bti? That's an acronym for Bacillus thuringiensis israelensis, a naturally occurring soil bacterium that's used to kill mosquito larvae in water. It's one of the primary materials used for mosquito control because it's relatively nontoxic to species that aren't mosquitoes. The city also sprays in areas where infected mosquitoes are detected. Indeed, anytime residents see a municipal spraying operation — always in the evenings — it is proof that the West Nile virus has been detected. There's no city spraying, Rockhill-Carpenter says, for the annoyance factor of mosquitoes alone.
"We have 15 traps that we set every week, and we do this between March and November every year," Rockhill-Carpenter said.
Twelve of those traps remain at the same location. The other three are moved around town based on complaints about mosquitoes or other factors.
"We collect the mosquito samples and submit them to Tarrant County's laboratory, where they speciate, count and test those mosquitoes for the presence of West Nile virus," Rockhill-Carpenter said. "Then, in Arlington, we follow the CDC (Centers for Disease Control) and the American Mosquito Control Association's best practices for the control of West Nile virus."
How many of those Arlington traps over the mosquito breeding season have ended up with positive virus contamination at least once?
"Basically, all of them," Rockhill-Carpenter said.
Rockhill-Carpenter said seven Arlington residents have been confirmed as having the virus so far this year, and countywide, the count is also up dramatically from last year. According to Tarrant County Public Health (TCPH), there has been a significant increase in West Nile virus for the 2024 season.
TCPH has found 28 human West Nile cases, with 24 hospitalized and one death reported, so far during the 2024 mosquito season. Across the county, 482 mosquito samples have tested positive for the virus. Comparatively, the 2023 season ended with 12 human cases and 244 positive mosquito samples — essentially a 100 percent increase. Those 2024 stats are, however, through mid-August. The final count, including deaths and hospitalizations, is expected to be higher.
What to do? Mosquitoes are most pervasive in the early morning or early evening, so avoid being outside during those times, or, if not possible or practical, apply a repellant and wear protective clothing. Report problem areas to the city. And take Rockhill-Carpenter's advice to not be your own worst enemy: Don't allow standing water in your yard. A container of water as small as a bottle cap can become a mosquito breeding site. It's also helpful to report neighborhood areas with long-standing stagnant water issues.
O.K. Carter is a columnist at the Arlington Report. You may contact him at .
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