From the LymeLight Newsletter of the Lyme Disease Foundation

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Researchers say a newly discovered species of Borrelia carried by Ixodes scapularis (black legged deer) ticks in some northeastern states are closely related to a relapsing fever bacterium.

The closest relative to the bacteria is Borrelia (B.) miyamotoi. B. miyamototoi is the causative agent of relapsing fever in Japan and is carried by Ixodes persulcatus ticks. According to researchers, the unnamed bacteria share a 99.3% genetic similarity with B. miyamotoi and a 95.4% similarity with B. burgdorferi, the causative agent of Lyme disease (LD). Borrelia are "spirochetes"or spiral-shaped bacteria.

Tests from ticks field-collected in Connecticut, Rhode Island, New York, and New Jersey revealed 1.9-2.5% of sampled ticks tested positive for the new Borrelia. All tests were negative from ticks collected from Maryland.

Researchers also discovered transovarial (mother to larvae) transmission of the new bacteria occurs in Ixodes scapularis ticks, with infection rates among tick larvae ranging from 6% to 73%. (Transovarial transmission of Bb occurs less than 1% of the time in Ixodes scapularis.)

While it remains unanswered if the new Borrelia causes disease in humans, researchers acknowledge that all other organisms that Ixodes scapularis ticks transmit to mice can also infect people.

As was reported in LymeLight, volume 2, 2001, researchers believe the organism has been present in the Northeast for a long time, and that existing Lyme disease tests will not detect the presence of the organism.

These important discoveries provide yet more examples of why some patients who have LD symptoms fail to test positive on LD tests, yet respond to antibiotic treatment. They also exemplify why a common sense approach to minimizing tick-borne diseases should include doctors treating with antibiotics on tick-bite.

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