Tuberculosis Caused by Mycobacterium microti in South American Camelids
Article first published online: 26 AUG 2009
Copyright © 2009 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 23, Issue 6, pages 1266–1272, November/December 2009
How to Cite
Zanolari, P., Robert, N., Lyashchenko, K.P., Pfyffer, G.E., Greenwald, R., Esfandiari, J. and Meylan, M. (2009), Tuberculosis Caused by Mycobacterium microti in South American Camelids. Journal of Veterinary Internal Medicine, 23: 1266–1272. doi: 10.1111/j.1939-1676.2009.0377.x
- Issue published online: 27 OCT 2009
- Article first published online: 26 AUG 2009
- Submitted January 12, 2009; Revised June 10, 2009; Accepted July 21, 2009.
- Infectious disease;
Background: Infection with Mycobacterium microti can cause chronic disease in animals and threaten human health through its zoonotic potential.
Objective: To describe clinical findings, diagnostic investigations, necropsy, and epidemiology results in South American camelids (SAC) infected with M. microti, member of the Mycobacterium tuberculosis complex.
Animals: Eleven SAC with tuberculous lesions.
Methods: Description of 10 llamas and 1 alpaca, aged 4–18 years, from 6 herds with a history of wasting and weakness admitted to the Vetsuisse-Faculty of Berne over 8 years.
Results: Clinical signs included weight loss, recumbency, and anorexia in late stages of the disease. Respiratory problems were seen in 6 animals of 11. No consistent hematologic abnormalities were identified. Suspect animals were examined in detail by abdominal ultrasonography and thoracic radiology. Abnormal findings such as enlarged mediastinal, mesenteric, or hepatic lymph nodes were seen only in animals with advanced disease. Single comparative intradermal tuberculin test with bovine protein purified derivate (PPD) and avian PPD was negative in all animals. At necropsy, typical tuberculous lesions were found, and confirmed by bacteriological smear and culture, molecular methods, or both.
Conclusions and Clinical Importance: Infection caused by M. microti should be considered a differential diagnosis in chronic debilitating disease with or without respiratory signs in SAC. Antemortem confirmation of the diagnosis remains challenging at any stage of infection. Because cases of M. microti infection have been reported in immunocompromized human patients, the zoonotic potential of the organism should be kept in mind when dealing with this disease in SAC.