Birds Play an Important Role in the Spread of Lyme Disease, Yale Study Finds

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Birds Play an Important Role in the Spread of Lyme Disease, Yale Study

Finds

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HealthNewsDigest.com) - New Haven, Conn. – The range of Lyme disease is

spreading in North America and it appears that birds play a significant role

by transporting the Lyme disease bacterium over long distances, a new study

by the Yale School of Public Health has found. The study appears online in

the journal Frontiers in Ecology and the Environment.

 

 

Researchers analyzed published records and concluded that at least 70

species of North American birds are susceptible to infection by black-legged

ticks (Ixodes scapularis), the principal vector of the Lyme disease bacterium

(Borrelia burgdorferi). The evidence also suggests that these bird species

are dispersing infected ticks into areas that had previously been free of

the disease, such as Canada.

 

 

Lyme disease bacterium is usually associated with small mammals such as

mice and squirrels. Immature ticks (in the larval and nymphal stages) become

infected with the bacterium when they feed on these mammals. During

subsequent blood meals, an infected tick transmits the infection to other

hosts,

including humans. White-tailed deer—while playing an important role in

maintaining and spreading tick populations—are a biological dead end for the

bacterium because its blood is immune to infection.

 

 

Birds, however, are not immune and numerous species get infected and are

capable of transmitting the pathogen onto ticks, the researchers found. What

remains to be seen is whether the B. burgdorferi strains that can infect

birds can also cause disease in humans. If so, the role of birds in the

epidemiology of Lyme disease could be profound.

 

 

“Birds are often overlooked in Lyme disease studies,†said Robert

Brinkerhoff, a post-doctoral student in Maria A. Diuk-Wasser’s lab at the

School

of Public Health and first author of the paper, “but they may be playing a

key role in its rapid expansion.â€

 

 

The researchers found that I. scapularis most consistently parasitizes

bird species such as thrushes, brown thrashers, wrens and wood warblers. The

authors estimate that as few as three individual birds are needed to infect

one black-legged tick with the bacterium.

 

 

Lyme disease can cause severe health problems, including arthritis,

nervous system abnormalities and irregular heart rhythm. It is the most common

vector-borne disease in the United States, with the number of reported human

infections doubling between 1992 and 2006.

 

 

Other authors of the paper include research assistant Corrine M. Folsom-O’

Keefe, Kimberly Tsao, a Ph.D. student and Maria Diuk-Wasser, assistant

professor, all at the Yale School of Public Health.