The bacteria that cause Lyme disease appear to hide out in the lymph nodes, according to a study from the University of California, Davis

This triggers a significant immune response, but one that is not strong enough to beat the infection, the study notes.

Results from this University of California Lyme disease study on mice appear online in the journal Public Library of Science Pathogens.

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"Our findings suggest for the first time that Borrelia burgdorferi, the bacteria that cause Lyme disease in people, dogs and wildlife, have developed a novel strategy for subverting the immune response of the animals they infect," said Professor Nicole Baumgarth, an authority on immune responses at the UC Davis Center for Comparative Medicine.

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Swollen lymph nodes is one of the hallmarks of Lyme disease, although it has been unclear why this occurs or how it affects the course of the disease.

"Overall, these findings suggest that B. burgdorferi hinder the immune system from generating a response that is fully functional and that can persist and protect after repeat infections," Baumgarth said. "Thus, the study might explain why people living in endemic areas can be repeatedly infected with these disease-causing spirochetes."

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Reference:

PLoS Pathog. 2011 May;7(5):e1002066. Epub 2011 May 26. "Lymphoadenopathy during lyme borreliosis is caused by spirochete migration-induced specific B cell activation." Tunev SS, Hastey CJ, Hodzic E, Feng S, Barthold SW, Baumgarth N. Center for Comparative Medicine, University of California Davis, Davis, California, United States of America.

Funding for the study was provided by the National Institute of Health (NIH).