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The objective of this study was to characterize the distribution of Mycobacterium paratuberculosis (Map) in the environment of infected and uninfected Minnesota dairy farms. Eighty herds known to be infected from Minnesota's Johne's Disease Control Program (JDCP) and 28 herds known to be uninfected from Minnesota Voluntary Johne's Disease Herd Status Program (VJDHSP) were sampled. Fecal samples from up to 100 cows in each herd were cultured in pools of 5 cows. Two environmental samples were obtained from each farm from various locations. All samples were tested using bacterial culture for Map. Eighty percent of the JDCP herds had at least one positive pool. Environmental samples were cultured positive in 78% of the JDCP herds. Two (7%) of the VJDHSP herds had one positive pool, and one herd had one positive environmental sample. Environmental samples were cultured positive in cow alleyways (77% of the herds), manure storage (68%), calving area (21%), sick cow pen (18%), water runoff (6%), and postweaned calves areas (3%). There was an association between maximum level of colonies per tube from cow alleyways and manure storage and fecal pool prevalence. Herds with both areas cultured negative were estimated to have 0.3 to 4% fecal pool prevalence. Herds with both areas having a heavy load of bacteria were estimated to have 53 to 73% fecal pool prevalence. The study results indicate that targeted sampling of cow alleyways and manure storage areas appears to be an alternative strategy for herd screening and Johne's infection status assessment and for estimating herd fecal prevalence.

Red-backed voles (Clethrionomys gapperi) were live trapped in northern St. Louis County, Minnesota (USA), in late September and October 1988 and experimentally inoculated with Borrelia burgdorferi. Spirochetes were isolated from most animals 14 and 28 days following inoculation. Thus, red-backed voles exposed to B. burgdorferi were susceptible to infection and could be a reservoir host, along with chipmunks (Tamias striatus) and other small rodents, in areas where white-footed mouse (Peromyscus leucopus) populations are low. No evidence of clinical disease was noted in any infected voles.

To determine the seroprevalence of Lyme disease in gray wolves (Canis lupus) from various counties of Minnesota and Wisconsin (USA), 589 serum samples were collected from 528 wolves from 1972 to 1989. An indirect fluorescent antibody (IFA) test was used to detect the presence of antibodies against Borrelia burgdorferi. Titers of greater than or equal to 1:100 were considered positive. Results were confirmed by testing a few selected sera by Western blotting. Of the 589 sera tested, 15 (3%) had IFA titers of greater than or equal to 1:100. Three of the positive samples were collected from Douglas County in Wisconsin and twelve were from Minnesota counties. This study indicates that wolves are exposed to B. burgdorferi and are susceptible to Lyme disease.

The distribution of Ixodes dammini in Minnesota was studied by collecting adult ticks from hunting dogs during the grouse seasons in September and October of 1985 and 1986. The tick was most frequently found in the east-central part of the state. Borrelia spp. were observed by immunofluorescence in 10% of the ticks. The locations where ticks were found coincide with the primary endemic areas for Lyme disease in the state.

Lyme disease spirochetes were isolated from the kidneys of two Peromyscus spp. trapped in Minnesota in September and October 1983. No spirochetes were isolated from white-tailed deer (Odocoileus virginianus), red backed voles (Clethrionomys gapperi), or shrews (Sorexy cinereus and Blarina brevicauda). This is the first report of the isolation of the Lyme disease spirochete from the midwestern United States and isolations from these animals, which were free of ticks, suggest that the Lyme disease spirochete may persist in animal organs for months.