Mice as reservoirs of the Lyme disease spirochete.

In evaluating the white-footed mouse as a reservoir host for the Lyme disease spirochete, we compared spirochete infection in vector ticks (Ixodes dammini) having different histories of attachment to these mice, estimated their relative importance as hosts for immature I. dammini and compared the seasonality of tick activity and spirochetemia in mice. Infection in trapped white-footed mice appears to be universal. Prevalence of spirochetal infection in I. dammini correlates with frequency of attachment to mice, and in mice, with the season of vector activity. The relative abundance of this mouse makes it numerically the most important host for I. dammini. Most immature I. dammini appear to attach to white-footed mice. Taken together, these considerations demonstrate that the white-footed mouse serves as reservoir for the Lyme disease spirochete in coastal Massachusetts.