Summer 2001

Volume 3 Number 3
A publication of Macon State College

Biting Back

Dr. Mike Womack's Mosquito Research Helps Fight West Nile Virus, Other Diseases

By Renee Pearman

Womack uses a hand aspirator to collect adult mosquitoes.

Mike Womack was the kid who spent afternoons chasing butterflies and lightning bugs and catching beetles and grasshoppers in the woods and fields surrounding his Hattiesburg, Miss., home. By the time he began his graduate studies at the University of Mississippi's School of Medicine, his childhood fascination with insects had evolved into an interest in health and disease.

Today, faculty at the Universiti Sains Malaysia, halfway around the world from Georgia, are familiar with the research of Dr. Michael Womack, professor of biology at Macon State College. His work also is well known among faculty at the University of Notre Dame's Disease Vector Biology Lab and the Centers for Disease Control's Dengue Fever Research Labs in Puerto Rico.

Womack has made a name for himself, as well as for Macon State College, through his extensive study of the disease-carrying Asian tiger mosquito and, more recently, the West Nile virus.

His lectures on "The Ecology of Emerging Diseases," "The Biology of the Asian Tiger Mosquito" and "Mosquito-borne Viruses in Georgia" have taken him from Central Georgia civic club meetings to hospitals, colleges and research labs across the country. And his pursuit of the Asian tiger mosquito has led him to the tropical Cayman Islands, the banks of North Carolina lakes and the backyards of houses in rural Georgia.

"This is a good time to be an entomologist," said Womack, who actually prefers the title disease vector ecologist, which, he explained, "is someone interested in any sort of arthropod that transmits diseases. It's really a whole new sub-discipline of entomology."

Tracking a 'Tiger'

By day, Womack teaches introductory biology, microbiology for health sciences and pathophysiology at Macon State College, but in the evenings and on weekends, he continues his mosquito research, which over the years has been funded by grants from the Federal Emergency Management Agency, the U.S. Department of Defense, the Tennessee Valley Authority and the University System of Georgia.

In the spring of 1991, Womack attended a lecture on the Asian tiger mosquito at the USAF School of Aerospace Medicine at Brooks Air Force Base in San Antonio. It renewed his interest in epidemiology, a branch of medical science dealing with the incidence, distribution and control of disease in a population. Since then, he has been tracking the Asian tiger mosquito, or Aedes albopictus, which is believed to have made its way into the U.S. in a cargo of tires imported from Japan to Houston, Texas, in 1985.

During a research fellowship to the USAF School of Aerospace Medicine in 1992, Womack surveyed communities in southern Texas to see how far the Asian tiger mosquito had traveled. He visited tire retailers, auto and truck repair shops, cemeteries, parks, plant nurseries -- any "resting sites" for tires -- and collected mosquitos using a hand aspirator. He concluded that the insect was "widely distributed" in that part of the state, 35 counties to be exact.

The following year his article "Distribution, Abundance and Bionomics of Aedes Albopictus in Southern Texas" was published in the Journal of American Mosquito Control Association," an international publication for mosquito research. Since then, lecture requests have been pouring in. "I found myself on a first-name basis with the mosquito guru, Dr. George Craig Jr. of the University of Notre Dame," said Womack, who several years ago was one of four nominees for the Georgia Public Health Association's Sellers-McCroan Award, which recognizes outstanding achievement and service in epidemiology and/or laboratory services.

Womack also has conducted a statewide mosquito survey in Georgia - and he has discovered Asian tiger mosquitos in all 159 counties.

When grouped by their habitat, mosquitos fall into three categories: permanent pool, floodwater or temporary pool, and container. The aggressive Asian tiger mosquito is a container mosquito, laying its eggs in water that accumulates in tree holes, bird baths, buckets, pet dishes and tires.

"Mosquitoes must have water to complete their life cycle," Womack said. "They lay their eggs in water or where water will pool, such as old tires lying in someone's backyard. Mosquito larvae feed on microscopic organisms and complete their development in water."
In the South where mosquitoes are common pests in the hot, humid months, why does the Asian tiger mosquito warrant so much attention?

These mosquitoes transmit dengue, which causes fever, headaches, muscle pains, rash, nausea, vomiting and chills. In its most severe form, dengue fever can lead to internal bleeding and death. Like pneumonic plague, Bengal cholera, Hantaviral infections, cryptosporidiosis, hemorrhagic fever and E. coli 0157, dengue is one of the emerging diseases that have become world health issues, according to Womack.

A Full Schedule

A native of Anna, Ill., Mike Womack was 12 when his family moved to Mississippi. At Hattiesburg (Mississippi) High School, he met his wife, Sylvia, who now is an assistant professor of nursing at Macon State College.

Womack received his bachelor of science and master of science degrees in biology and science education from the University of Mississippi. Coincidentally, he did his master's research on disease-transmitting mosquitos. While completing his doctorate at the University of Southern Mississippi, he learned of a teaching position in Macon State College's Division of Natural Sciences and Mathematics. He joined the faculty in 1977.

The biology professor's teaching schedule is full. In addition to his normal course load at Macon State, he occasionally offers a non-credit course on "Emerging Diseases, The Media and The Public" in which he covers the global ecology of representative emerging diseases and the accuracy of information transmitted to the general public. He is director of an arthropod ecology lab, which he established at Macon State 10 years ago with grant funds.

Michele Wright of Elko asks Dr. Mike Womack, center, about an assignment in his Biology 1101 lab.

He also has taught microbial physiology and biology at the Georgia Institute for Technology, and he is an adjunct assistant professor of public health at Mercer University's School of Medicine.

A 35-year member of the Air Force Reserve, Womack serves as a major in the Reserve's Biomedical Science Corps. Earlier this summer he spent two weeks at Robins Air Force Base training personnel on how to combat potential mosquito infestation on the 8,722-acre base.

"We're still tracking the Asian tiger mosquito in Georgia, but now we have a brand new ball game -- the Asian bush mosquito, which was discovered in New Jersey about two years ago," said Womack, who is a member of the Georgia Mosquito Control Association and the American Association of Mosquito Control.

The Asian bush mosquito can transmit the West Nile virus, which Womack predicts will makes its way to Georgia by the end of this summer. He is a member of a West Nile Task Force for Georgia, which is developing a state response plan to the virus.

The West Nile virus first appeared in Uganda more than 70 years ago, and since then outbreaks have been reported in Africa, Europe, the Middle East, Russia and India. The first cases in the U.S. were reported in New York City in 1999, and so far, the virus has spread to 13 states, including North Carolina and Florida.

Georgia's West Nile Task Force team is conducting what Womack calls passive surveillance, "looking for symptomatology in hospitals and clinics and asking health departments to collect reports of dead birds."

Birds are the reservoirs for the virus. "Humans can get infected because the ticks and mosquitoes that feed on infected birds also feed on humans," Womack said. "We know the Asian bush mosquito transmits the virus, and we believe the same is true of the Asian tiger mosquito." Symptoms of West Nile virus are similar to influenza and if untreated can develop into encephalitis.
How can we protect ourselves from these disease-spreading mosquitoes?

"Keep your yards clean," Womack advised. "Make sure there is no standing water in your yard. Empty buckets. Keep pet bowls and bird baths clean. Take care of out-door drainage problems."

Work Is Never Done

In May 2000, Womack was one of three Georgians serving on a 60-member committee representing the American Mosquito Association (AMA) who headed to Washington, D.C., to solicit funding for additional mosquito research. The committee briefed Congress members on the threat of the West Nile fever and the need for supporting recent laws aimed at enhancing mosquito surveillance in 19 eastern states. The arrival of the virus into the northeastern U.S. demonstrates how easily emerging infectious diseases can travel into new geographic areas, Womack testified.

Following the committee's visit, the U.S. Health and Human Services (HHS) secretary announced that an additional $5 million would be provided for states to expand the surveillance activities for the West Nile virus, thus doubling the Centers for Disease Control and Prevention's fiscal 2000 funding for the project. Womack explained that the additional funding from Congress goes from HHS to the Centers for Disease Control in Atlanta, which then filters the funds to district health departments in states where West Nile virus outbreaks have occurred.

Meanwhile, Womack continues to survey mosquito populations in the Southeast and to educate the public -- via his classroom lectures and international presentations -- about mosquito-borne viruses. In this age of emerging infectious diseases, a disease vector ecologist's work is never done.