Infestation of the southern alligator lizard (Squamata: Anguidae) by Ixodes pacificus (Acari: Ixodidae) and its susceptibility to Borrelia burgdorferi.

To investigate the reservoir potential of the southern alligator lizard, Elgaria multicarinata (Blainville), for the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, 14 lizards were collected from 1 county on each side of the northern Central Valley of California. Seven animals were collected from a Placer County site (Drivers Flat) and a Yolo County site (Cache Creek) where B. burgdorferi had been isolated previously from Ixodes pacificus Cooley & Kohls. Overall, the mean abundance of I. pacificus on all 14 lizards was 34.1 (range, 3-63) for larvae and 11.0 (range, 1-28) for nymphs. In captivity, field-attached I. pacificus larvae and nymphs required, on average, 12.6 (range, 1-37) and 14.4 (range, 5-44) d to feed to repletion, respectively. The prevalence of B. burgdorferi infection in host-seeking I. pacificus nymphs was 1.4% in Cache Creek Canyon and 9.9% in Drivers Flat. Attempts to isolate spirochetes from lizard blood or ticks that had fed on lizards and subsequently molted were unsuccessful as were efforts to cultivate spirochetes in lizard sera. These data suggest that the southern alligator lizard is not a competent reservoir for B. burgdorferi, although it is an important host for I. pacificus subadults.