Culturing Borrelia burgdorferi from spleen and kidney tissues of wild-caught white-footed mice, Peromyscus leucopus.

Borrelia burgdorferi was isolated most frequently from tissue of spleen (n = 13) and kidney (n = 10) and less often from blood (n = 5) of wild-caught Peromyscus leucopus. Prevalence of infection tended to be highest at sites where Lyme disease was most common (e.g., 5 of 6 mice were positive in East Haddam, Connecticut). Spirochetes were not isolated in Danbury or New Hartford, areas where this malady is rare. However, in Fairfield, where the disease is also uncommon, 4 of 9 mice were infected. Larval and nymphal I. dammini, containing borreliae, parasitized P. leucopus at all sites where B. burgdorferi was cultured from mice. Borreliae were also detected in D. variabilis feeding on hosts at two of the sites. P. leucopus appears to be an excellent animal to identify focal areas of B. burgdorferi.