Mosquitoes are on the rise after the rains we experienced last week in Dallas and Fort Worth. Hopefully West Nile counts stay low this year for all areas.
Although mosquitoes have tested positive for the West Nile virus in a handful of suburbs this year, local health officials are hoping for a mild season with few human infections.
“It appears to be a slow start,” Zachary Thompson, director of Dallas County Health and Human Services, said Friday.
“But in past years, we’ve seen slow starts and then a surge of cases in July,” he recalled of the mosquito-borne virus, which first appeared in North Texas in 2002.
As of this week, no West Nile infections had been reported in local residents. As of June 14, the county has tested 1,834 mosquito pools and found none contained insects carrying West Nile.
However, independent labs that perform tests in some Dallas County cities found infected mosquitoes in ZIP codes 75137 in Duncanville, 75104 in Cedar Hill, 75019 in Coppell and 75038 in Irving.
A mosquito pool in Tarrant County’s Benbrook — ZIP code 76116 — also tested positive for the virus this week, according to Tarrant’s public health department.
Each positive report is followed by pesticide spraying within a half-mile radius of the infected trap. This year, local cities and counties are committed to spraying within 24 hours of a positive test result or confirmed human infection. Some are hoping for an even faster turnaround.
“The environmentalists don’t like our spraying with any kind of pesticides, but we will do only what’s needed,” said James Martin, director of Dallas code compliance, which handles mosquito-control efforts. So far, no spraying has been needed in Dallas.
Some cities, however, are deciding to spray even before West Nile is confirmed.
Hurst officials announced Friday they would conduct a “fogging” of all city streets between Tuesday and Thursday next week. They explained it as “our proactive approach to fight the mosquito population and help prevent West Nile virus.” Spraying will run from 9 p.m. to 5 a.m. each night.
Mosquito surveillance has gradually become a year-round activity since West Nile first appeared in North Texas. Last year, officials in four counties — Dallas, Denton, Collin and Tarrant — agreed to collaborate on a regional abatement effort.
During last year’s outbreak, 16 Dallas County residents suffered mild to severe West Nile infections, and two of them died. In 2012, the county was the national epicenter for West Nile with more than 400 people sickened and 20 deaths.
West Nile is a virus harbored in birds that can be spread to people by mosquito bites. The severity of each annual appearance, from April through September, has been difficult to predict.
Officials are hoping last winter’s colder temperatures will stave off a deadly outbreak like the one in 2012. It followed a mild winter and wet spring, both of which seemed to favor mosquito productivity.
“There are so many variables involved,” said Dr. Christopher Perkins, medical director for the Dallas County health department. “We just have to monitor the situation and act accordingly.”
Thompson said recent Dallas County surveillance has picked up a gradual increase in Culex mosquitoes, the type most likely to carry West Nile. Of the nearly 8,000 specimens tested so far, all were negative.
“Daily rain and heat will probably drive our mosquito counts up,” he said.
Dead bird counts, another early indicator of an outbreak, also are down this year. So far, a dozen dead birds have been reported to Dallas County, compared with 21 in the same period last summer.
Keeping down the local mosquito population will depend largely on ridding the area of standing water, breeding sites for the insects. Small amounts of water in flower pots and bird baths should be drained by residents. Larger bodies of stagnant water can be treated with “mosquito dunks,” compact insectide pellets that kill mosquito larvae.
Dallas County spent about $20,000 this year for more than 10,000 of these mosquito-control products, being distributed free by 25 cities in the county. The county and local cities also are handing out more than 10,000 donated cans of insect repellent, mostly to senior citizens.
“We want people to use repellent whenever they go outdoors, all day long,” Thompson said.