Students Use Satellite Imagery To Track Lyme Disease-Carrying Ticks

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University students participating in a NASA internship program are using imagery from the U.S. space agency’s Terra Earth-observing spacecraft and DigitalGlobe’s Quickbird commercial remote sensing satellite to reveal hospitable habitats for ticks that spread Lyme disease.

In June, the students began identifying the most likely breeding grounds for ticks in central Alabama. They plan to expand the study this fall to map the entire state, said Nathan Renneboog, team leader for the project.

The trick is to find areas where dense vegetation and high soil moisture create the right environment for breeding of the black-legged ticks. Renneboog is one of six University of Alabama, Birmingham, students who along with one student from Boston University and one from Louisiana State University are interns participating in the Marshall Space Flight Center’s Develop Program, a NASA applied sciences training effort that encourages students to use space agency data to address local issues. The interns are based at the University of Alabama’s Laboratory for Global Health Observation, a research center that uses satellite observations to support health-related projects.

Before the students began their research, few Alabama residents were concerned with Lyme disease, Renneboog said. The disease is far more prevalent in New England states such as Connecticut where more than 3,000 cases were reported in 2007 compared to only 13 cases in Alabama, according to the most recent data from the U.S. Centers for Disease Control and Prevention.

As a result, the student project began with an effort to determine whether the Lyme disease bacteria had been infecting local animals. Once the students confirmed that, they began using a combination of satellite imagery and geographic information tools to pinpoint the most likely tick habitats, Renneboog said.

During their initial search for ticks, the students focused on an area of central Alabama stretching from Birmingham to Tuscaloosa. NASA provided the students with imagery captured by Terra’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) while Alabama View, a state consortium that promotes the use of remote sensing and geographic information systems, gave the students data from the Quickbird, a satellite owned and operated by Longmont, Colo.-based DigitalGlobe.

The students used ASTER and Quickbird imagery to identify the areas of dense vegetation and areas of high soil moisture and then used Google Earth to create maps showing where the two areas intersected. “The biggest area was around the Warrior River in central Alabama,” Renneboog said. “That’s where we found the most likely habitat for these ticks.”

As the students begin expanding their research this fall to cover the entire state, they plan once again to use ASTER and Quickbird imagery to identify the heavily wooded areas where ticks breed. During the statewide project, the interns also plan to use Quickbird imagery, which offers resolution of 61 centimeters for black-and-white images and 2.4 meters for multispectral data, to identify specific types of vegetation.

“Even though dense vegetation is a strong indicator for tick populations, research has shown that Oak trees are a better indicator,” Renneboog said. Oak groves, which provide habitats for common Lyme disease carriers like white-tailed deer and cotton mice, are the areas where people would be most likely to contract Lyme disease, he added.

During the fall semester, students also will obtain samples of the ticks from high risk areas to test whether they carry Lyme disease, said Jeffrey Luvall, senior research scientist at the Marshall Space Flight Center in Huntsville, Ala., and science adviser for the student-led team.

Lyme disease is often accompanied by a bull’s-eye rash, headache and fever. The recognizable rash makes the illness easy to diagnose immediately, Luvall said. It is also easy to treat at that stage because it responds well to antibiotics. Left untreated, however, the rash disappears, and the disease becomes far more difficult to detect because its symptoms mimic those of a wide range of illnesses. Without treatment, Lyme disease can lead to serious complications of the heart, nervous system and joints, Luvall added.

Simply by alerting local residents to the possibility of Lyme disease and its hallmark rash, the students are providing a valuable service, Luvall said. Through an extensive public outreach campaign that includes papers, posters and a video, they are helping Alabamans learn about the disease and even how to safely remove ticks, he added.

During the final stage of the project, which is scheduled to conclude in November, the students plan to conduct a statewide risk-perception survey to determine whether people are worried about contracting Lyme disease. Information derived from that survey will help the students frame a new community outreach campaign, Renneboog said.

As part of their ongoing effort to alert residents to the presence of Lyme disease-carrying ticks, the students presented the results of their central Alabama study this summer to local health officials and Alabama news organizations. Since then, they have received e-mails from people who had Lyme disease for years without an accurate diagnosis, Luvall said.

In October, the students plan to present their findings at a meeting of the Lyme and Associated Diseases Society in Washington, Renneboog said.