Students find employment seeking keys to deadly disease

Timothy Bender and Desiree Del Orbe are among the USF undergraduate students learning about the ecology of Eastern equine encephalitis with the help of Hassan K. Hassan, MSc (center), a research associate in Dr. Thomas Unnasch’s laboratory.

While we spent the summer and entered the fall abuzz over the potential for H1N1 virus, or the ‘Swine Flu,’ to sweep the nation, some University of South Florida students and one high school student found employment that put them in search of mosquitoes carrying a rarer but deadlier virus, Eastern equine encephalitis, or EEE.

“Eastern equine encephalitis is rare, but when humans get the disease the fatality rate is 50 to 70 percent,” says Thomas Unnasch, PhD, a professor in the USF Department of Global Health, College of Public Health. “It is nearly 100 percent fatal for horses. The ecology of EEE in the Southeastern United States is not well understood.”

Beneficiaries of NIH stimulus funding

Dr. Unnasch, who has had ongoing funding from the National Institutes of Health to study the ecology and transmission of EEE and several other diseases, received additional funding under the “American Recovery and Reinvestment Act of 2009” which allocated $21 million nationally over two years for educational supplements to existing research programs. The stimulus funding has provided extended summer employment for more than 3,000 undergraduates and high school students nation-wide.

With his supplemental grant, Dr. Unnasch was able to hire six USF undergraduates and one high school student to take an active role in tracking down which of the 60-plus varieties of mosquitoes in the Tampa Bay area carry EEE. In addition, his collaborators at Auburn University were also able to hire student summer researchers.

The goal of the research is to identify the vectors (the mosquitoes) carrying the EEE virus and identify their feeding sources. Some EEE carrying mosquitoes feed exclusively on birds, says Dr. Unnasch, while others may feed on mammals of several varieties. Because of suburban development, mosquitoes carrying EEE may be coming into closer contact with people, especially in rapidly developing areas such as Hillsborough and Pasco Counties, where USF undergraduate student Timothy Bender and Raphael Shattenkirk, a student at Tampa Preparatory School, trap mosquitoes several days a week.

“Raphael sets the traps in the evening and I pick them up in the morning,” explains Bender, a biology major.

Mosquitoes caught in netted traps left overnight in developing areas of Hillsborough and Pasco counties are frozen and brought to the laboratory for analysis under the microscope. The researchers want to identify the mosquitoes carrying EEE and their feeding sources.

The traps attract mosquitoes using a small light bulb, the release of carbon dioxide from dry ice left overnight, and a small fan that sucks them into the netted traps. In the morning, Bender pops the trap bag in the freezer, which kills them, and then he delivers them to the USF lab where USF undergraduate student Desiree Del Orbe puts the dead mosquitoes, up to 60-100 per day, under the microscope and sorts them by sex, species, and which of the females (the only mosquitoes that bite) have had a recent “blood meal,” evidenced by their swollen bellies. These are the mosquitoes of interest, the ones that may be carrying EEE.

“Ultimately, we want to determine which mosquitoes carry the virus, the source of their blood meals, and the ecological area where the mosquitoes were active,” says Del Orbe. “This information will help the counties with mosquito spraying when they can target specific areas.”

According to Dr. Unnasch, Florida spends $75 million annually on mosquito control, but the efforts are not as efficiently targeted as they could be if we understood more about the ecology of the virus.

Hands-on Research Experience

Students in the lab, under the supervision of Hassan K. Hassan, MSc, research associate, run a battery of tests, including real-time Polymerase Chain Reaction (PCR) to look for virus RNA, and DNAPCR tests on the blood meal to determine meal source. Their results are shared with both the state Department of Health and the county mosquito control offices. In this win-win summer research project not only do the counties get good data, but students learn the research process from field to bench.

“They get to learn about lab safety,” says Hassan. “They learn why we use this chemical or that one, they learn to use the lab equipment and how to avoid sample contamination. Many students would not learn these things until graduate school.”

Christy Ottendorfer, PhD, a post-doctoral fellow in the lab, says that 2009 has been a “big year” for EEE because of the rainfall amounts and the increased mosquito populations. “Fortunately there have been no human cases, but Florida is leading the nation in equine deaths from EEE,” says Dr. Ottendorfer.

There is a “known unknown” in EEE research. The big issue for the research team is to find what they call the “bridge species” of mosquito. “If mosquitoes carrying the virus feed on birds and non-human mammals, how do people get it?” asks Ottendorfer.

According to Dr. Unnasch, the student researchers are indispensable.

“The real hard part of this research is getting people out there to do the field work, the sample collections,” he says. “It helps to have a bunch of enthusiastic people willing to get out there to set the traps and collect samples. Their help has allowed us to increase the number of collection sites.”

The other benefit to having student help is that with an increase in good data, the NIH is more likely to continue funding the project. The stimulus funding runs through Oct. 31, and then many of the students will continue to work on the project as volunteers, says Hassan.

- Story and photos by Randolph Fillmore, Florida Science Communications