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.
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.
In early February, Dallas 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. In response, the Centers for Disease
Control and Prevention put its emergency operations center on the highest level of
activation to respond to an outbreak.
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
Steven M. Presley, professor, The Institute of Environmental and Human Health, (806)
885-0236 or email@example.com
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
“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
The Institute of Environmental and Human Health was created in 1997 as a joint venture between Texas Tech and the Texas Tech University
Health Sciences Center to assess the impact of toxic chemicals and diseases on the
physical and human environments, including air, water, soil and animal life.
Researchers investigate elements in the environment, both those that are naturally
occurring such as disease and those caused by humans, such as nuclear activity, pollution
or chemical or bioterrorism, which negatively impact the environment. It is one of
the few labs in the country dedicated to environmental toxicology.