A new species of bacteria is causing Lyme disease, adding to worries that the infection will continue its relentless escalation across the United States. Lyme is already the most common tick-borne disease in North America, with new cases peaking every June and July.
“In summary, the news is largely bad,” Paul Mead of the U.S. Centers for Disease Control and Prevention said June 19 at a joint meeting of the American Society for Microbiology and the Interscience Conference on Antimicrobial Agents and Chemotherapy. Not only is the prevalence of Lyme disease increasing, another tick-borne illness — Rocky Mountain spotted fever — is cutting a deadly path through Mexico.
Public health officials began collecting data on Lyme disease in 1991. Since then, it has spread in all directions from two U.S. epicenters, one in the Northeast and one in the Upper Midwest, according to data Mead presented at the meeting and published last year in Emerging Infectious Diseases. In the early 1990s, 43 Northeast counties had a high incidence of the disease. Today, 182 do. About 30,000 to 35,000Lyme disease cases are reported each year in the United States, up from around 11,000 cases in 1995, the CDC reports.
Until recently, only one bacterium in North America was known to cause the disease: Borrelia burgdorferi. (In Europe, two other species are more common.)This year, researchers at Mayo Clinic testing blood and synovial fluid samples from people infected with Lyme disease discovered six infections that did not trace to B. burgdorferi. In addition to a rash, fever and other classic Lyme symptoms, those patients also experienced confusion, nausea and vomiting. “Not so typical for Lyme disease,” Mead observed.-read more
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