Lora Ballweber hopes her hot pursuit of ticks across Mississippi will help people evade life-threatening diseases carried by the bloodthirsty parasites, while heading off another potential risk for U.S. cattle farmers.
The Mississippi State veterinary scientist not only wants to know what makes ticks tick--but where they tick, when they tick and why they tick. That's the ticket.
Her two-pronged university probe into environmental factors related to tick-borne diseases is propelled by a $100,000 NASA grant focusing on the pest as one of many public health issues; and two USDA grants totaling nearly $75,000 aimed at preventing the spread of cattle-killing Heartwater fever from the Caribbean area to U.S. shores.
"NASA's interest is in using remote sensing technology to obtain data for predicting and preventing a variety of diseases, including those borne by ticks," said Ballweber, a Cody, Wyo., native and member of the College of Veterinary Medicine faculty since 1993. "The USDA interest is geared more toward cattle and biosecurity."
The blood-feeding external parasites of mammals, birds and reptiles include approximately 850 species throughout the world. Two well-established families, the Ixodidae (hard ticks) and Argasidae (soft ticks), are important vectors of disease-causing agents to humans and animals--including potentially fatal Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, babesiosis, tularemia, and tick-borne relapsing fever.
Lyme disease, commonly carried by deer ticks, has become more widespread with the increasing construction of homes in wooded areas. According to the Centers for Disease Control and Prevention, a total of 23,763 cases were reported during 2002--an increase of 40 percent over 2001. The human body has no natural immunity to Lyme.
Ballweber and several MSU research colleagues--utilizing a tick-collecting technique called "drag sampling"--are seeking to determine which species are endemic to Mississippi, which diseases they carry, which areas of the state have the most infestation, and which seasons of the year produce the most risk. They also want to know if distribution patterns change over time.
"At the moment, we're most interested in Rocky Mountain spotted fever, which is more prevalent in Mississippi than Lyme disease, and human granulocytic ehrlichiosis, a disease that's only been identified within the last five to eight years," said the associate professor and authority in parasitology. "We want to find out where this (HGE) organism is and determine its potential risk to residents of Mississippi."
Aiding her research are colleagues Bill Cooke, an assistant professor of geosciences, and Rich Minnis, an assistant research professor of wildlife and fisheries. Both experts in remote sensing and geographic information systems, they are using automated computer software to model geographic and climatic conditions associated with the spread of tick-borne diseases.
"There is a limited view of all the factors associated with complex biological systems and there's some thought that we may not have been going deep enough into those issues, that the quality of the data has not always been the best," said Cooke, who is conducting similar research into environmental factors related to West Nile virus. "GIS helps deal with the problem of evaluating and connecting all of the data."
CVM epidemiologist Carla Houston provides statistical validity for the project and veterinary doctoral student Kelsey L. McNally of Rossville, Tenn. also assists in the research. Jackson-based officials of the U.S. Department of Agriculture, and the state's Department of Health, Board of Animal Health and Veterinary Diagnostic Laboratory also are involved.
"One of our goals is to produce tick-distribution maps," said Ballweber, a big-game bowhunter whose husband, Jeff, is an MSU water resources professor. "Based on our tick samplings, we'll use remotely sensed data such as vegetation type, soil types, moisture indicators and temperatures to map areas of highest incidence for specific types of ticks, and the areas of highest risk for the diseases they're carrying."
The separate-but-related Heartwater disease research is conducted within Advanced Spatial Technologies in Agriculture, a USDA program administered by Mississippi State. Endemic to the Caribbean islands, Africa and some other parts of the world, Heartwater does not yet occur in the United States. Ballweber said, however, the Gulf Coast tick (Amblyomma maculatum Koch) found in Mississippi, "is quite capable of transmitting this disease.
"We want to determine the distribution of this tick in Mississippi so we can identify the highest areas of risk and be prepared to deal with those areas quickly, should the disease ever be introduced into the state," added the DVM graduate of Oregon State and Washington State universities.
Heartwater, also called cowdriosis, is transmitted exclusively by three-host Amblyomma ticks under natural conditions and is a major threat to exotic cattle breeds. Cattle from non-endemic areas are very susceptible to the disease.
"It has the potential of devastating cattle herds," said Ballweber of the disease.
NEWS EDITORS/DIRECTORS: For information, contact Dr. Ballweber at Lora Ballweber or (662) 325-1345.
