Texas Tech University

Expert Can Discuss Zika Virus

Glenys Young

June 16, 2016

Steven M. Presley

Zika virus, primarily transmitted by mosquitoes, was first discovered in Uganda in 1947. For decades, it was known as a short-lived, relatively mild illness with no long-lasting effects. That all changed in September when Brazilian doctors noticed a 1,400 percent spike in congenital brain deformities in a part of Brazil that experienced a Zika outbreak months earlier.

The first case of Zika virus in the United States was confirmed in early February in Dallas, when that city's health officials reported a man infected a partner during sex. Brazilian scientists then announced they had found live strains of the virus in the urine and saliva of infected individuals.

Steven M. Presley, a professor of immunotoxicology in The Institute of Environmental and Human Health at Texas Tech University, focuses on the risks and threats associated with biological pathogens with the goal of developing and fielding preventative measures against vector-borne infectious and zoonotic diseases. He runs a lab within the institute that collects and studies mosquitos for West Nile virus, St. Louis encephalitis virus and Chikungunya. Presley earned his bachelor's degree in animal science with a master's and doctorate in medical/veterinary entomology. He also is the chairman of the publications committee and on the science and technology committee of the American Mosquito Control Association, and serves as the regional director of the south central U.S. for the Society for Vector Ecology.


Steven M. Presley, professor, The Institute of Environmental and Human Health, (806) 885-0236 or steve.presley@ttu.edu

Talking points

  • Unlike with West Nile virus, which requires an animal (bird) host to amplify the virus between mosquitoes and humans, Zika virus can amplify in humans. This makes the transmission cycle much faster.
  • Only one in five people infected with Zika virus shows symptoms. Because those are similar to the symptoms of influenza, many people who show symptoms are never properly diagnosed, which makes the disease difficult to track.
  • The mosquitoes that transmit Zika are Aedes aegypti and Aedes albopictus. They are day-biting, human-loving and have biologies and behaviors different from many of the species that vector West Nile virus and St. Louis encephalitis virus.
  • Little is known about Zika, especially the full spectrum of the mosquito transmission and hosts dynamics.
  • Mosquitoes from the Lubbock area will be screened for Zika virus as Aedes aegypti and Aedes albopictus activity increases.
  • Mosquito treatment spraying often occurs overnight when other species are active. Cooler overnight air allows the spray to settle into the grass, and warmer air in the daytime carries spray away, making it ineffective at treating for Aedes mosquitoes.


  • "Because there's not an intermediate amplifying host and only one in five people are symptomatic with Zika virus, the transmission cycle is sped up, and amplifying hosts may not be recognized. You have these amplifying hosts out there promulgating the virus and mosquitoes are feeding and biting somebody else without you ever knowing it's occurring in the area."
  • "Probably the fetuses and newborns with microcephaly are the most tragic outcome of the disease, but they're finding more and more information on neurological involvement in Brazil in adults and not just infants."
  • "Whether Zika virus has shifted or drifted in its antigenic properties, we really don't know with the current outbreak that's going on. There's something that's caused it to be much more widespread, whether it's increased mosquito numbers, environmental factors that may influence more mosquitoes being infected with it or more mosquitoes in an area."
  • "We could potentially have a person who is asymptomatic but infective, circulating enough virus that mosquitoes could pick it up. We're a university town. We've got a lot of people coming and going from foreign places where they might become infected and bring the virus back. It's going to require a lot of vigilance this coming spring and summer."
  • "Aedes aegypti and albopictus are container breeders: Vases at cemeteries, toys in the backyard, garbage – a Styrofoam coffee cup thrown in the alley. Just a little bit of water can produce a lot of those mosquitoes, while the typical West Nile and St. Louis encephalitis vectors are pond, puddle, standing water, established water breeders."