According to the National Oceanic and Atmospheric Administration National Climate Center, the Houston region experienced severe drought conditions in May and June.
Jeff Flosi, University of Houston-Downtown associate professor of biology and microbiology, says mosquitoes that carry the West Nile virus successfully breed under drought conditions.
“Water left behind during drought becomes concentrated stagnant pools, preferred by the Culex quinquefasciatus (southern house mosquito), a mosquito that transmits St. Louis encephalitis and West Nile virus,” said Flosi. “The recent rainfall will produce significant numbers of flood-water mosquitoes over the next week to 10 days. These same rains will very often flood out the more organic, standing water habitats preferred by the Culex mosquitoes.”
As the principal investigator of the Medical Entomology Laboratory in the UHD Department of Natural Sciences, he leads students in forensic entomology research and microbial ecology research in Houston’s Glenwood Cemetery, and in other locations.
Flosi and the students target Culex mosquitoes and test to see if they are carrying diseases. “All of our testing for the presence of mosquito-borne viruses has been negative for this season,” said Flosi. If they find positive pools of mosquitoes, he shares the information with the Texas Department of State Health Services surveillance program.
Flosi notes the southern house mosquito has remained at comparable levels for the last five years, and exhibited natural declines this season due to the availability of breeding habitats, particularly in proximity to human habitations. Other species of Culex mosquitoes seem to have declined in their sampling areas in Harris County, Texas, he said.
Before joining UHD in 1987, Flosi studied mosquito population dynamics as the laboratory superintendent and chief entomologist for the Harris County Mosquito Control District.
More than 50 of the 3,000 kinds of mosquitoes worldwide live in Harris County. Several types carry diseases that can spread to humans and animals. Disease-carrying mosquitoes generally appear from April to October in the Houston area. Other species, such as the salt marsh mosquito, persist year-round.
St. Louis encephalitis is the most common mosquito-borne disease in the United States and in Harris County. Symptoms for it and the West Nile virus include fever, headache, nausea, vomiting, stiff neck, trembling and changes in mental function, such as sleepiness or disorientation. Victims of the virus may also suffer from tiredness, body aches, occasionally a skin rash and swollen lymph glands.
Gulf Coast residents can protect themselves outdoors by using mosquito repellent, eliminating standing water on their property, and adding or fixing screens on windows and doors. Pet owners should eliminate standing water, control weeds and vegetation around the home, keep pets indoors at dawn and dusk, and use outdoor yellow “bug” lights to reduce their pets’ exposure to mosquitoes.