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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Infectious Bacterial Diseases Research » Research » Publications at this Location » Publication #122103
Title: SUSCEPTIBILITY OF RACCOONS (PROCYON LOTOR) TO INFECTION WITH MYCOBACTERIUM BOVIS

Author
item Palmer, Mitchell
item Waters, Wade
item Whipple, Diana

Submitted to: Journal of Wildlife Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Tuberculosis due to Mycobacterium bovis infection is endemic in white-tailed deer in the northeastern portion of the lower Michigan peninsula. Various wild carnivores and omnivores, including raccoons, have also been found to be infected with M. bovis within the affected area. It is believed that raccoons and other animals are becoming infected by feeding on tuberculous deer carcasses. In order to determine whether raccoons can become infected with M. bovis through ingestion, investigate the development of disease, and determine the likelihood of M. bovis transmission from infected raccoons to other susceptible hosts, we experimentally inoculated raccoons with a single oral exposure to various dosages of M. bovis, repeated (5 days) oral exposure to various dosages of M. bovis, or a single IV inoculation of M. bovis. Disease consistent with tuberculosis was seen in 1/5 raccoons in the single low oral dose group, 1/5 raccoons in the multiple low oral dose group, 2/5 raccoons in the multiple medium oral dose group, 5/5 raccoons in the multiple high oral dose group, and 5/5 raccoons in the IV inoculated group. Excretion of M. bovis in saliva or nasal secretions was seen in 5/5 IV inoculated raccoons and 2/5 multiple low oral dose raccoons. Mycobacterium bovis was not isolated from urine or feces from any experimentally inoculated raccoons. The necessity of multiple large oral dosages to establish infection in raccoons, and the low number of orally inoculated raccoons that excrete M. bovis in nasal secretions or saliva, make it unlikely that raccoons serve as important reservoir hosts of M. bovis, or transmitters of M. bovis to other susceptible hosts.

Technical Abstract: Tuberculosis due to Mycobacterium bovis infection is endemic in white-tailed deer in the northeastern portion of the lower Michigan peninsula. Various wild carnivores and omnivores, including raccoons, have also been found to be infected with M. bovis within the endemic area. To investigate the pathogenesis of tuberculosis in raccoons and the likelihood of M. bovis transmission from infected raccoons to other susceptible hosts, we experimentally inoculated raccoons with single oral dosages of M. bovis (ranging from 30 to 1.7 X 10**5 CFU), repeated (5 days) oral dosages of M. bovis (ranging from 10 to 1 X 10**5 CFU), or a single IV dose of 1 X 10**5 CFU of M. bovis. Granulomatous lesions consistent with tuberculosis, or tissue colonization with M. bovis, were seen in 1/5 raccoons in the single low oral dose group, 1/5 raccoons in the multiple low oral dose group, 2/5 raccoons in the multiple medium oral dose group, 5/5 raccoons in the multiple high oral dose group, and 5/5 raccoons in the IV inoculated group. In orally inoculated raccoons, lesions were most commonly seen in the tracheobronchial and mesenteric lymph nodes and lung. Excretion of M. bovis in saliva or nasal secretions was seen in 5/5 IV inoculated raccoons and 2/5 multiple low oral dose raccoons. Mycobacterium bovis was not isolated from urine or feces from any experimentally inoculated raccoons. The necessity of multiple large oral dosages to establish infection in raccoons, and the low number of orally inoculated raccoons that excrete M. bovis in nasal secretions or saliva, make it unlikely that raccoons serve as important reservoir hosts of M. bovis, or transmitters of M. bovis to other susceptible hosts.