"It's much harder to get blood from a tick, which usually takes only one blood meal per life stage," Thach says. "By the time we capture the tick, eight months to a year may have elapsed. The tick has had a long time to digest that blood, so there may be only a tiny amount of DNA left if there's any."
The team did two assays on tick DNA: one to identify pathogenic bacteria and the other to identify the animal that provided the tick's last blood meal.
The results showed that more blood meals were taken from deer in honeysuckle-intact plots.
The assay also looked for Ehrlichia chaffeensis and Ehrlichia ewingii, among other pathogens. Both bacteria were once thought to cause disease only in animals but have been found to infect people as well.
Ehrlichiosis is the general name used to describe several bacterial diseases that affect animals and humans. The first case of human ehrlichiosis was diagnosed in 1986.
A case of ehrlichiosis caused by another bacterium was identified in 1999 by Gregory A. Storch, MD, the Ruth L. Siteman Professor of Pediatrics at Washington University's School of Medicine. Worldwide, four ehrlichia species are currently known to cause disease in humans.
Ehrlichiosis begins with symptoms typical of bacterial infection, such as fever, headache, fatigue and muscle aches. More serious symptoms, such as joint pain and confusion, may occur and in rare instances the disease is fatal.
Thach says that when he goes into the woods he wears special anti-tick underwear called Bug Skinz and permethrin-saturated clothing over that. Thach's lab is currently investigating Ehrlichia bacteria in squirrels and local Ehrlichia hotspots, locations where the pathogen is found every single time the scientists sample.
The irrepressible Allan is more en
|Contact: Diana Lutz|
Washington University in St. Louis