According to the Centers for Disease Control, each year, approximately 30,000 cases of Lyme disease are diagnosed. A spirochete bacterium called Borrelia burgdorferi causes the disease, and blacklegged ticks are responsible for the majority of North American cases of the illness.
Oils from garlic and several other common herbs and medicinal plants show strong activity against the bacterium that causes Lyme disease, according to a study by researchers at Johns Hopkins Bloomberg School of Public Health. These oils may be especially useful in alleviating Lyme symptoms that persist despite standard antibiotic treatment, according to the authors.
The study included lab-dish tests of 35 essential oils. The researchers found that 10 of these, including oils from garlic cloves, myrrh trees, thyme leaves, cinnamon bark, allspice berries and cumin seeds, showed strong killing activity against dormant and slow-growing “persister” forms of the Lyme disease bacterium.
“We found that these essential oils were even better at killing the ‘persister’ forms of Lyme bacteria than standard Lyme antibiotics,” says study senior author Ying Zhang, MD, PhD, professor in the Department of Molecular Microbiology and Immunology at the Bloomberg School.
Standard treatment with doxycycline or an alternative antibiotic for a few weeks usually clears the infection and resolves symptoms, especially if the person catches it early. However, about 10 to 20 percent of patients report persistent symptoms including fatigue and joint pain—often termed “persistent Lyme infection” or “post-treatment Lyme disease syndrome” (PTLDS) that in some cases can last for months or years.
The research team found that essential oils from oregano, cinnamon bark, clove buds, citronella and wintergreen killed stationary phase Lyme bacteria even more potently than daptomycin, the chiefly used pharmaceutical for Lyme.
In the new study Zhang and his team extended their lab-dish testing to include 35 other essential oils, and found 10 that show significant killing activity against stationary phase Lyme bacteria cultures at concentrations of just one part per thousand. At this concentration, five of these oils, derived respectively from garlic bulbs, allspice berries, myrrh trees, spiked ginger lily blossoms and may change fruit, successfully killed all stationary-phase Lyme bacteria in their culture dishes in seven days, so no bacteria grew back in 21 days.
Oils from thyme leaves, cumin seeds and amyris wood also performed well, as did cinnamaldehyde, the fragrant main ingredient of cinnamon bark oil.
The team is seeking to continue investigations of essential oils with tests in live animals, including tests in mouse models of persistent Lyme infection. If those tests go well and the effective doses seem safe, Zhang expects to organize initial tests in humans. “At this stage these essential oils look very promising as candidate treatments for persistent Lyme infection, but ultimately we need properly designed clinical trials,” he says.
Feng, Zhang, et al. “Identification of Essential Oils with Strong Activity against Stationary Phase Borrelia burgdorferi.” Antibiotics, 2018; 7 (4): 89 DOI: 10.3390/antibiotics7040089
