Genetic, phenotypic, and behavioral variation in North American sylvatic isolates of Trichinella.

Two restriction endonucleases (Cla I and Hpa II) produced polymorphic repetitive DNA profiles which were used in a clustering analysis to quantify the level of genetic variation among 14 North American sylvatic isolates of T5 Trichinella. Differences in genetic profiles reflected phenotypic differences in parasite reproductive success as measured by an isolate's reproductive capacity index in natural hosts. Two genetically distinct isolates of the T5 genotype and T. spiralis were used to infect white-footed mice Peromyscus leucopus for a behavioral analysis. Three behavioral characteristics were tabulated from videotapes: time to emerge from cage, time spent inside cage, and number of rears (index of exploratory activity). Mice infected with 400 T. spiralis larvae showed a significant decrease in exploratory activity and significant increases in time to emerge and time spent inside cage, whereas mice infected with 200 larvae displayed no differences in behavior. Mice infected with a T5 isolate from a raccoon (R9) also displayed decreased exploratory activity. In contrast, mice infected with the other T5 isolate from a coyote (C26) showed relatively constant rearing levels but spent less time inside their cages during the late period of the infection. Results suggest that different genetic strains of Trichinella induce varied types of behavioral modifications upon their hosts.