Oils from garlic and other common herbs and medicinal plants are showing promise in the lab for treating the bacteria that causes Lyme disease, and may prove especially useful in treating those who continue to have symptoms after antibiotic treatment, Johns Hopkins University researchers have found.
The findings, still in the early stages, come just after the U.S. Centers for Disease Control and Prevention released data showing that tick-borne diseases such as Lyme are on the rise nationwide. Last year, state and local health departments reported 59,349 cases, up from 48,610 the years before. The case numbers have been rising for years to last year's record, though the reasons are unknown.
Maryland reported 1,887 cases of Lyme last year, 13 more than in 2016, according to the state Department of Health.
Cases are not always diagnosed, and Hopkins researchers say there are likely 300,000 new cases of Lyme annually in the United States. For most people, a course of doxycycline or other antibiotic clears up the infection in a few weeks.
But 10 to 20 percent experience lasting symptoms that include fatigue and joint pain.
Some researchers have speculated that this persistent Lyme infection, or post-treatment Lyme disease, is a new disorder triggered by the initial infection. The Hopkins researchers also say the Lyme bacteria, Borrelia burgdorferi, can enter a stationary or slow-growing phase, and so-called persister cells from the bacteria are more resistant to antibiotics.
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The oils from garlic and other herbs may prove better than antibiotics at tackling those cells, according to the Hopkins study, published Oct. 16 in the journal Antibiotics.
The research included lab-dish tests of 35 essential oils, pressed from plants or their fruits. Ten of these, including oils from garlic cloves, myrrh trees, thyme leaves, cinnamon bark, allspice berries and cumin seeds, showed the strongest killing activity against the Lyme persister cells.
"We found that these essential oils were even better at killing the persister forms of Lyme bacteria than standard Lyme antibiotics," said study senior author Dr. Ying Zhang, professor in the department of molecular microbiology and immunology in the Hopkins Bloomberg School of Public Health.
Zhang previously found that antibiotic combinations and drugs used to treat resistant bacteria, such as MRSA, work better than standards antibiotics in treating Lyme disease. He plans to test the oils in animals and later in humans.