Experimental Infection of Richardson’s Ground Squirrels (Spermophilus Richardsonii ) With Attenuated and Virulent Strains pf Brucella abortus

Authors

Pauline Nol, USDA-APHIS-Wildlife ServicesFollow
Steven C. Olsen, USDA, Agricultural Research Service, National Animal Disease Center
Jack C. Rhyan, USDA-APHIS-Wildlife Services

Document Type

Article

Date of this Version

2009

Comments

Published in JOURNAL OF WILDLIFE DISEASES, 45(1), 2009, PP. 189–195.

Abstract

A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various nontarget species suggested that Richardson’s ground squirrels (Spermophilus richardsonii) may develop persistent infections when orally inoculated with the vaccine. In the present study, sRB51, B. abortus strain 19 (s19), and virulent B. abortus strain 9941 (s9941) were administered orally to Richardson’s ground squirrels to further characterize B. abortus infection in this species. Six groups of nongravid ground squirrels were orally inoculated with 6x10⁸ colony forming units (cfu) sRB51 (n=10), 2.5x10⁴ cfu s19 (n=10), 2.5x10⁷ cfu s19 (n=6), 1.3x10⁶ cfu s9941 (n=5), 2.1x10⁸ cfu s9941 (n=5), or vaccine diluent (control; n=4). One of five animals in the lower-dose s19 group and two of three animals in the higher-dose s19 group showed persistence of bacteria in various tissues at 14 wk post-inoculation (PI). At 18 wk PI, one of five animals in the sRB51 group and one of five animals in the high-dose s9941 group were culture positive. Although we did detect some persistence of B. abortus strains at 18 wk, we found no evidence of pathology caused by B. abortus strains in nonpregnant Richardson’s ground squirrels based on clinical signs, gross lesions, and microscopic lesions.