The recent heavy rains in North Texas have definitely increased the mosquito population, but it has also delayed the start of West Nile season.
How is this possible? Well, the mosquitos that are currently active and biting are Aedes vexans, or “floodwater mosquito.”
These particular mosquitos normally do not carry West Nile virus or other mosquitoborne illnesses that can affect humans. In fact, the mosquito that carries the West Nile virus in North Texas prefers stagnant water found during droughts, like the ones we’ve seen the past two years.
“This sudden explosion of mosquitos is a result of the recent rains which have flooded lowlying areas where Aedes vexans mosquito eggss have laid dormant for two years,” said Scott Sawlis, Entomologist for Dallas County Health and Human Services (DCHHS). “And while, these mosquitos do bite and are definetly a pest they do not pose a risk of exposing humans to mosquito borne illnesses such as West Nile Virus. In North Texas the culex mosquito or southern house mosquito is the vector for West Nile virus,” Sawlis continued.
“Since the average person can’t distinguish between the flood water and house mosquitos, we encourage everyone to use the increase mosquito activity as a trial run for West Nile Season and to be on the defense against mosquito bites,” said Zachary Thompson, DCHHS Director. DCHHS encourages everyone to remember the three Ds to defend against West Nile ? Dress in light color, long clothing; Drain all standing water; and wear DEET or other insect repellent.
Want to know if mosquitos carrying West Nile virus are in your neighborhood? This publication is distributed by email weekly during mosquito season and contains a list of lcoations within Dallas County where mosquito samples have tested positive for West Nile Virus. “The West Nile Watch is another of our tools in the fight against West Nile. Knowing that mosquitos carrying the virus are in your immediate area, should send up a red flag to the public for the need to protect themselves, their families, and their homes,” Thompson continued.
Studies have shown that the majority of people who contracted the more serious form of West Nile virus did not use insect repellent. In 2006, Dallas County reported 101 confirmed human cases of West Nile virus and four deaths. In 2005, Dallas County had 43 confirmed human cases of West Nile with one death. In 2004, DCHHS reported a total of 16 human West Nile cases (6 with West Nile fever and 10 with neuroinvasive West Nile) with no deaths. In 2003, Dallas County had a total of 54 human West Nile cases with 4 deaths. In 2002, the first year the virus was reported in Dallas County, there were 27 human cases with 3 deaths.
DCHHS continues to work with its municipal partners on additional strategies to protect Dallas County residents from mosquitoborne illnesses.
DCHHS West Nile prevention activities include surveillance, source reduction, larvaciding (killing mosquito larvae or wigglers), adulticiding (spraying for adult mosquitoes), and public education. Dallas County has enhanced is early detection capability through the use of gravid traps for mosquito collection and global positioning systems equipment provided by the Texas Department of State Health Services (DSHS).