Several counties in North Texas — one of the hardest hit regions by West Nile virus in recent years — have announced a coordinated effort to prevent and monitor the spread of the mosquito-borne infectious disease.
Collin, Dallas, Denton and Tarrant counties are stepping up efforts with early tracking of the illness, with more than 1,200 mosquito traps. These traps help identify WNV hot spots when infected mosquitoes test positive.
WNV season officially begins in April and runs through November; however, the virus can be transmitted year-round — whenever mosquitoes are biting. Unfortunately, predicting how severe the upcoming WNV season is difficult.
"Data should be analyzed over many years to be able to predict appropriately the severity of a particular WNV season," said Anita K. Kurian, associate director of Tarrant County Public Health.
"WNV activity was first recorded in Tarrant County in 2002, and therefore the data is limited. Furthermore, multiple data elements modulate and add layers of complexity to accurately predicting the risk and the severity of WNV transmission."
Although it may not predict the severity of the season, Tarrant County has an interactive mapping system available to residents online. The map shows the locations of mosquito traps and confirmed WNV. It is updated twice weekly.
Texas reported 172 cases of WNV in 2013, resulting in 13 deaths, according to the latest information available from the Centers for Disease Control and Prevention.
Nationally, 2,347 cases were reported in 48 states and Washington, D.C., with 114 deaths. The previous year saw 5,674 cases, resulting in 286 deaths.
According to Denton County Health Director Bing Burton, the way WNV is reported is changing. In years past, a fever was a requirement for diagnosing WNV; however, this year health officials will be able to classify the disease from other symptoms and lab work. The goal is to have a more accurate count of cases, and Burton anticipates an increase in the number of cases because of the reporting changes.
Severe symptoms of WNV can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, paralysis, nausea, vomiting, swollen lymph nodes or a skin rash on one's chest, stomach or back.
According to a fact sheet distributed by Tarrant County Public Health, about 80 percent of people who are infected with WNV will not show any symptoms at all. Those who do get sick typically develop symptoms between three to 14 days after an infected mosquito bites them.
There are 78 diseases that healthcare providers are required to report to county health departments, and WNV is among them.
Plano, a city in Collin County, is using Gambusia affinis, commonly known as the mosquito fish, to help control the pesky population of bloodsuckers. And they're not alone.
"The mosquito fish feeds on mosquito larvae and can be used effectively as a biocontrol to lower mosquito population, thereby theoretically aid in combatting WNV indirectly," Kurian said. "Tarrant County has offered mosquito fish to collaborating municipalities free of charge since 2004."
So is there hope for a WNV-free existence?
Although a vaccine does not exist right now, recent studies from Arizona State University suggest a drug produced in tobacco plants can be used to neutralize WNV infections in mice infected with a lethal dose of the disease, marking an important first development in the fight against WNV. The challenge, of course, is bringing an affordable drug to the market.
In the meantime, people are encouraged to follow the four Ds to avoid mosquitoes that may transmit the virus:
- Dress to avoid mosquito bites by wearing long, loose and light-colored clothing when outside;
- Defend yourself by using insect repellents approved by the EPA or CDC;
- Dusk and dawn: Limit outside activities during these hours when possible, and especially if not dressed and prepared with repellent; and
- Drain all areas of standing water in and around the home, including wading pools, pet dishes and birdbaths.
