EXPERIMENTAL-INFECTION OF COLUMBIAN BLACK-TAILED DEER WITH THE LYME-DISEASE SPIROCHETE

The course of Borrelia burgdorferi-infection in Columbian black-tailed deer (Odocoileus hemionus columbianus), its effect on the health of t hese animals, and their reservoir competence for fleas were evaluated experimentally. Four yearling females inoculated intramuscularly with 10(3) organisms of the CA4 strain of B. burgdorferi, and two yearling males unexposed to spirochetes, were monitored daily for 3 mo. Spiroch etes were reisolated from the blood of three does at 14 or 70 days pos tinjection, and from several tissues of the fourth doe at necropsy. Co nsiderable antigenic heterogeneity was observed among the reisolates a s determined by sodium dodecyl sulfate-polyacrylamide gel electrophore sis. Only two of the four infected deer developed significant antibodi es (greater than or equal to 1:128) to B. burgdorferi with titers pers isting for less than or equal to 2 mo. Hematological values were highl y variable and the degree of variation observed was much greater than that reported previously for Columbian black-tailed deer or other subs pecies of mule deer. Infected deer did not manifest signs of Lyme dise ase. On histologic examination of eight tissues per deer, we observed a minimal hepatic lesion in all animals exposed to B. burgdorferi. No spirochetes were detected in 367 fleas (Pulex irritans) that had natur ally infested these deer; thus this flea probably is an inefficient ho st of B. burgdorferi.