A Crowley resident has been identified as the first West Nile virus case in Tarrant County this year.
The patient has contracted the neuroinvasive form of the disease, which is the most debilitating strain. Tarrant County Public Health has not recorded any positive samples from the testing of mosquito pools in Crowley.
Because it is not known where the patient contracted the disease, the city has no plans to take any additional mosquito abatement countermeasures, police spokeswoman C.C. Meadows said.
“We do not spray unless it’s necessary and to this point it has not been necessary,” Meadows said. “We’ve not seen any increases in the count and we have not had a positive test sample.
Officials did not release the age, name or sex of the patient to protect the person’s identity, Tarrant County Public Health said in a news release.
In 2013, the agency reported its first human case on May 26. For the entire 2013 season, it reported nine human cases of West Nile virus, including two deaths. Most people infected, about 80 percent, with the virus show no symptoms.
The more severe form of the virus is often called West Nile neuroinvasive disease. Most patients who have contracted that straingare over 50, and many have underlying health conditions, said Anita Kurian, associate director of Tarrant County Public Health.
The mild form of the disease is commonly called West Nile fever. People typically recover on their own, although symptoms may last several weeks.
Typically the West Nile virus peaks in 3- to 5-year cycles. The last peak year was in 2012, when Tarrant County reported 280 cases of the virus and 11 deaths. That year, Texas led the nation in cases, with 1,868 including 89 deaths.
“It’s difficult to predict how a season will be in the beginning,” Kurian said. “A mild winter, a warm summer and enough rain to form breeding sites, all the necessary factors to produce a large mosquito population, were there in 2012.”
Female mosquitoes live about a month and have two to three laying cycles, Kurian said. A female mosquito will lay anywhere from 200 to 400 eggs at one time, and after the eggs hatch the larvae take about a week to reach adulthood, Kurian said.
Tarrant County officials elected to initiate ground spraying Monday after finding a positive mosquito sample in the area around Ruth’s Court in northwest Tarrant County. Typically, the health agency recommends ground spraying once a positive mosquito sample has been located in an area, Kurian said.
But spraying works only if it is a part of a coordinated effort to control mosquitoes, Kurian said.
“Ground spraying is only effective for killing adult mosquitoes,” Kurian said. “It has to be supported by larvaciding and source reduction.”