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The Birthplace of Lyme Disease
September/October 2008
by Emily Anthes '05
New Haven’s neighbor, Lyme, Connecticut, is off the
hook. Lyme disease originated in Europe, according to new research.
Lyme disease, which is transmitted to humans by ticks,
is the most common vector-borne disease in the United States. It is caused by
the bacterium Borrelia burgdorferi, which is more common in the United States than in Europe.
Many researchers therefore believed the bacterium originated on this side of
the Atlantic. (The first cluster of the disease in the United States was
documented by Yale scientists in and around Lyme, giving the condition its
name.)
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Lyme disease is the most common vector-borne disease in the U.S.
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Researchers from England’s University of Bath and the
Yale School of Public Health collected samples of Borrelia burgdorferi from various locations in this
country and Europe. They then examined the samples to determine the sequence of
eight so-called housekeeping genes, which control the bacterium’s basic
metabolic processes. By analyzing the number of mutations present in samples,
the researchers were able to determine which strains were the oldest, and then
draw a phylogenetic tree, a diagram of the samples' evolutionary history. The
tree showed that the European samples of B. burgdorferi made up a group distinct from the
American ones. The European lineage more closely resembled the common ancestor
of all the samples—leading the scientists to deduce that the bacterium first
emerged in Europe and only later jumped the pond. (The research appeared on
June 24 in the Proceedings of the National Academy of Sciences.) The Lyme organism, says Durland
Fish, an epidemiologist at the School of Public Health and one of the study's
lead authors, has “probably been here for hundreds of thousands of years.”  |
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