Birds Play an Important Role in the Spread of Lyme Disease

Dec 23, 2009

(PhysOrg.com) -- 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 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 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.” 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 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.

Explore further: Routines most vital in avoiding Ebola infection: WHO

add to favorites email to friend print save as pdf

Related Stories

Scientists identify potential key to Lyme disease

Feb 09, 2009

Researchers at UT Southwestern Medical Center have identified a protein that may help give Lyme disease its bite. The findings suggest that the bacterial protein, which aids in transporting the metal manganese, is essential ...

Recommended for you

Routines most vital in avoiding Ebola infection: WHO

13 hours ago

Meticulously following stringent routines when putting on and removing protective equipment is more important than the kind of gear health care workers use to ward off Ebola infection, the World Health Organization said Friday.

A look at latest Ebola developments

14 hours ago

No African countries are on the United Nations list of contributors to fight Ebola. With few exceptions, African governments and institutions are offering only marginal support as the continent faces its ...

Liberia opens one of largest Ebola treatment centers

14 hours ago

Remembering those who have died in the world's deadliest Ebola outbreak, Liberia's president opened one of the country's largest Ebola treatment centers in Monrovia on Friday amid hopes that the disease is ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

blackgsd
not rated yet Dec 31, 2009
" The authors estimate that as few as three individual birds are needed to infect one black-legged tick with the bacterium."

Is this a mistake? Considering the life cycle of Ixodes scapularis - which feeds on only three hosts in its life, the last being a large mammal such as a deer - it seems highly unlikely that this tick would feed on three birds in its lifetime.

I am also unclear as to why a tick would have to ingest blood containing the Lyme bacterium three times in order to become infected.

Gil. Ash

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.