At major centres across Canada, ticks carrying the Lyme disease bacterium have been collected from songbirds.
Those locations include Montreal, Toronto, Thunder Bay, Winnipeg, and Victoria. Fergus tick researcher John D. Scott, of the Lyme Disease Association of Ontario, and his colleagues have discovered that songbirds widely disperse millions of Lyme disease vector ticks across Canada.
The blacklegged tick is the primary vector of Lyme disease east of the Rocky Mountains. Of the blacklegged ticks tested from eastern and central Canada, researchers found that 36% of them were infected with B. burgdorferi.
For the first time, Lyme-carrying blacklegged ticks were discovered in Quebec, Saskatchewan, northern New Brunswick, and northern Ontario on songbirds. Millions of bird-transported ticks, which are infected with B. burgdorferi, are dispersed nationwide, especially during spring migration.
On the west coast, these researchers have noted that four different tick species are involved in a web-like, four-tick cycle at one locality on Vancouver Island. Songbirds and small mammals store and supply Lyme bacteria to and involve at least four different tick species and, subsequently, transmit them to other hosts, including people.
Immature larval ticks, which were infected with B. burgdorferi, were detached from 9 different songbird species, and these collections show that certain songbirds act as competent reservoirs for Lyme disease infection. Since these baby larval ticks had not taken a blood meal previously, they would not have had a chance to pick up the Lyme disease infection anywhere else.
For example, songbirds, such as the American Robin, can harbour B. burgdorferi in their bodies, and later transmit Lyme bacteria to non-infect ticks. When bird-feeding ticks have taken a complete blood meal, they drop to the cool, moist leaf litter or grassy mulch, and undergo a 6-8 week molt (rest period) before they bite people or domestic animals.
Songbirds that are heavily infested with B. burgdorferi-infected ticks have the potential to initiate new tick populations endemic for Lyme disease. Because songbirds carry the ticks, and distribute them across Canada, people do not have to frequent an endemic area to contract Lyme disease. In fact, Canadians can get Lyme disease in their own backyards.
The peer-reviewed, scientific article was recently published in the Journal of Parasitology, a peer-reviewed, world-renowned scientific journal. Co-authors include Dr. John F. Anderson, Connecticut Agricultural Experiment Station, New Haven, Connecticut and Dr. Lance A. Durden, Department of Biology, Georgia Southern University, Statesboro, Georgia.
For more information contact John D. Scott; email: jkscott@bserv.com. A PDF version of the article is available from the lead author. It is also listed on the Lyme Disease Association of Ontario website: www.lymeontario.org. As well, the revised brochure, Lyme Disease in Ontario, is listed on the website, and provides pictures of various Lyme rashes and symptoms of Lyme disease.
