Tick Risk Reduced By Ground Cover Type
Ground cover yields Lyme tick clues
NEW YORK (Reuters) -- Avoiding the natural habitat of the wood tick that transmits Lyme disease can significantly reduce the risk of picking up the infection when enjoying the outdoors, according to researchers.
"Awareness, recognition and avoidance of these high-risk areas may markedly reduce the risk for exposure to Lyme and other tick-borne infections," conclude Drs. Steven Schutzer and Bart Holland of the University of Medicine and Dentistry of New Jersey in Newark.
Lyme disease is caused by the microorganism Borrelia burgdorferi, transmitted to humans by the bite of infected ticks. Common symptoms (which are usually transient) include rash, aching joints, and fever.
In an article published in The Lancet last year, Schutzer and his colleagues pointed out that mice (not deer) are the favorite host of the ticks that transmit Lyme disease. The authors wrote that mice prefer thick "ground cover, which is extremely important for protection, whereas open space is dangerous (for the mice)." The Lancet report determined that tick concentrations were 23 times higher in areas of thick ground cover, compared with open spaces.
In a follow-up study published in the current issue of the Annals of Internal Medicine, Schutzer and Holland had pairs of investigators randomly choose and explore "different 10-square-yard areas in the woods during nymphal tick season" for periods of 2 hours.
Those researchers who explored areas with the type of dense ground cover beloved by mice (greater than 3 inches high with no visible bare spaces) were later examined and found to have become host to an average of 4 to 5 ticks.
In contrast, participants who spent their time in low-density areas (foliage less than 1-inch high and with large areas of bare ground) picked up less than one (0.2) tick each.
"This indicates that the risk for exposure is 22 times greater in the high-suitability areas than in the low-suitability areas," the investigators conclude. They recommend that hikers and campers concerned about Lyme disease stick to well-worn paths or relatively bare ground as a method of avoiding tick bites and Lyme infection. SOURCE: Annals of Internal Medicine (1998;128:784)