A treponema-like spirochete was detected in and isolated from adult Ixodes dammini , the incriminated tick vector of Lyme disease. Causally related to the spirochetes may be long-lasting cutaneous lesions that appeared on New Zealand White rabbits 10 to 12 weeks after infected ticks fed on them. Samples of serum from patients with Lyme disease were shown by indirect immunofluorescence to contain antibodies to this agent. It is suggested that the newly discovered spirochete is involved in the etiology of Lyme disease.

No abstract

We isolated spirochetes from the blood of 2 of 36 patients in Long Island and Westchester County, New York, who had signs and symptoms suggestive of Lyme disease. The spirochetes were morphologically similar and serologically identical to organisms recently found to infect lxodes dammini ticks, which are endemic to the area and have been epidemiologically implicated as vectors of Lyme disease. In both patients, there was a rise in specific antispirochetal antibodies in paired specimens of serum. We conclude that the l. dammini spirochete has an etiologic role in Lyme disease.

The role of the host plasminogen activation system in transmission of and invasion by Borrelia burgdorferi, the tick-borne spirochetal agent of Lyme disease, was investigated using plasminogen (Plg)-knockout mice. PLG was not detected in spirochetes from unfed ticks, but binding occurred as ticks fed on the host's blood. Plasminogen activators were derived from the host blood meal. PLG was required for efficient dissemination of B. burgdorferi within the tick and for enhancement of spirochetemia in mice but was not critical for transmission and infection. These results provide evidence for a bacterium using a vertebrate protease to disseminate in an invertebrate vector and underscores the interplay among vector, pathogen, and host in promoting the life cycle and disease.