New Orleans—Pharmacists practicing in areas with high rates of Lyme disease see it all the time: Patients who already have received antibiotic treatment for the disease still complain of lingering symptoms.

Now, recent studies might help explain why. The research, which raises the question of whether treatment is long enough, was reported in PLOS ONE and the American Journal of Pathology.

Tulane University researchers conducted a single, extensive study of Lyme disease, using a variety of methods to determine the presence of Borrelia burgdorferi spirochetes, the bacteria that cause Lyme disease, before and after antibiotic treatment in primates. Also measured was the antibody immune response to the bacteria, both pre- and posttreatment.

Results indicate that living B burgdorferi spirochetes were discovered in ticks that fed upon the primates, as well as in multiple organs, after treatment with 28 days of oral doxycycline. 

“It is apparent from these data that B burgdorferi bacteria, which have had time to adapt to their host, have the ability to escape immune recognition, tolerate the antibiotic doxycycline and invade vital organs such as the brain and heart,” said lead author Monica Embers, PhD, assistant professor of microbiology and immunology at Tulane University School of Medicine.

“In this study, we were able to observe the existence of microscopic disease and low numbers of bacteria, which would be difficult to ‘see’ in humans but could possibly be the cause of the variable and nonspecific symptoms that are characteristic of post-treatment Lyme disease syndrome,” Embers explained. “Although current antibiotic regimens may cure most patients who are treated early, if the infection is allowed to progress, the 28-day treatment may be insufficient, based on these findings.”

Researchers determined that all rhesus macaque primate subjects treated with antibiotics were found to have some level of infection 7 to 12 months posttreatment, and that, despite testing negative on antibody tests for Lyme disease, two of 10 subjects were still infected with Lyme bacteria in the heart and bladder.

That species was selected because those monkeys have a progression of Lyme disease most similar to humans, particularly related to erythema migrans, carditis, arthritis, and neuropathy of the peripheral and central nervous systems, the researchers point out.
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