First human West Nile case in 2015 reported in Tarrant County

Tarrant County’s first human West Nile case of this year has been confirmed in the southwestern part of the county near Benbrook, health officials said Friday.

The unidentified patient has West Nile neuroinvasive virus, the most severe form, said Tarrant County Public Health Director Vinny Taneja. The health department won’t say if the person is male or female or had any underlying health conditions.

Symptoms for the neuroinvasive form include neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. This form of the virus can be deadly.

About 1 percent of those bitten by an infected mosquito get the more serious form.

“We did get a history of mosquito bites,” Taneja said. “This person did recall being bitten by mosquitoes in recent weeks.”

Up to 80 percent of those infected with West Nile show no symptoms; about 20 percent will develop West Nile fever. Symptoms of that include fever, nausea and fatigue along with muscle and joint aches. Most recover on their own, but it can take several weeks.

Last year, the first of 16 Tarrant County human West Nile cases overall was reported Aug. 4. There were no deaths.

So far, nothing indicates that this is going to be a more serious West Nile season.

“We’re pretty much in the ballpark of what we saw last year,” Taneja said. “A couple of neighboring counties have seen cases, and this might be the beginning of where we start seeing more human cases.”

Tarrant County’s worst year for West Nile was 2012, when there were 280 human cases and 11 deaths. Texas led the nation in 2012, with 1,868 cases and 89 deaths

Dallas County reported its first 2015 human case, which was West Nile fever, on July 21. Johnson and Kaufman counties have also reported one case, according to the Texas Department of State Health Services

“We just need to keep our fingers crossed,” said Dallas County Health and Human Services Director Zachary Thompson. “It appears not to be as robust as in 2012. The key point is definitely use mosquito repellant.”

Besides bug repellant, individuals are encouraged to wear protective clothing from dusk until dawn. Residents should also dump standing water around their homes.

On Friday night, the city of Fort Worth was planning to spray over a portion of the 76133 ZIP code. Testing at Fire Station No. 29 over several weeks has collected four positive samples.

Spraying was scheduled to take place from 9 p.m. Friday through 5 a.m. Saturday.

If there is a weather delay on Friday night, the spraying will be pushed to Saturday evening.

Arlington also announced spraying in parts of the city from 9 p.m. Monday to 5 a.m. Tuesday. The spraying is the result of seven positive traps at the following locations: Mansfield Webb Road and Ballweg Road, South Bowen Road and Buffalo Drive, Pioneer Parkway and Carter Drive, Greek Row Drive and Kerby Street, Saddle Ridge Road and Yachtclub Drive as well as Douglas Court and North Cooper Street.

Burleson also announced ground spraying in portions of the city for today and Sunday.

Spraying reduces the number of adult mosquitoes, but it isn’t clear how much it reduces the incidence of West Nile infections in humans.

The overall number of mosquitoes caught in traps has been higher this year for about 2,500 samples tested.

Typically, 75 to 80 mosquitoes are caught in traps, but this spring between 300 and 400 were found in each trap. Those numbers have been dropping steadily in recent weeks since the rainfall has stopped.

“Just because we’ve had a lot of mosquitoes doesn’t mean we’ll have a lot of cases,” Taneja said. “The virus is carried by birds, so it really depends on the birds passing through. It’s just really hard to predict.”

This story was originally published July 31, 2015 at 2:25 PM with the headline "First human West Nile case in 2015 reported in Tarrant County."