Canine exposure to Borrelia burgdorferi and prevalence of Ixodes dammini (Acari: Ixodidae) on deer as a measure of Lyme disease risk in the northeastern United States.

Surveillance programs that identify areas where both the vector (Ixodes dammini) and etiologic agent (Borrelia burgdorferi) are present may identify the risk of Lyme disease and its spread earlier and more accurately than do programs relying on any single method, particularly human case reports. Hunter-killed deer (n = 1,204) from 22 counties in Maryland, Massachusetts, New Hampshire, New York, and Pennsylvania were examined in fall 1989 and all ectoparasites were identified. The following spring, canine sera (n = 884) were obtained from these sites, which included known endemic areas and those where Lyme disease is uncommon, and tested by enzyme-linked immunosorbent assay. Regression analysis of canine seroprevalence versus tick prevalence on deer from the same counties demonstrate a significant positive linear relationship. Sites were designated as low-, moderate-, or high-risk counties based upon their position on the regression curve. The geographic distribution of the sites correlated well with the distribution of known Lyme disease endemic and nonendemic areas. Locations were also identified where Lyme disease may be emerging. The positive relationship between measures of vector and pathogen abundance determined in this study permits public health workers to identify endemic and potentially endemic areas independently of human case reports.

Straight mutants of Spirillum volutans can swim.

Nonhelical mutant cells of Spirillum volutans ATCC 19554 can swim as fast as the helical cells. Consequently, a helical cell shape is not required for motility of this species, and the function of the polar flagellar fascicles is not merely to cause rotation, and therefore translocation, of the corkscrew-shaped cell.

The Microaerophile SPirillum volutans: Cultivation on Complex Liquid and Solid Media.

Spirillum volutans grows only under microaerobic conditions in a peptone-succinate-salts broth, but can grow aerobically when the peptone is replaced by vitamin-free acid-hydrolyzed casein broth. The addition of potassium metabisulfite, norepinephrine, catalase or superoxide dismutase (SOD) permitted aerobic growth in peptone-succinate-salts broth. A combination of catalase and SOD had a synergistic effect. S. volutans lacked catalase and had only a low level of peroxidase activity, but did possess SOD activity (12 to 14 U/mg of protein). The organism was found to be extraordinarily sensitive to exogenous hydrogen peroxide. Illumination of peptone-succinate-salts broth generated hydrogen peroxide and rendered the medium inhibitory to growth. A combination of catalase and SOD prevented this inhibition. Growth of S. volutans on solid media, not previously possible, was accomplished by the use of vitamin-free acid-hydrolyzed casein and peptone-succinate-salts agar media; maximum growth responses were dependent on the following combination of factors: addition of bisulfite, catalase, or SOD, protection of the media from illumination, incubation in a highly humid atmosphere, and incubation under atmospheres of 12% oxygen or less. The results indicate that the microaerophilic nature of S. volutans is attributable largely to the high sensitivity of the organism to exogenous hydrogen peroxide and, to a lesser extent, superoxide radicals occurring in the culture medium.