Outbreak of Mycobacterium marinum infection among captive snakes and bullfrogs

Abstract

Since 1985 mycobacterial infection has been observed occasionally among snakes and bullfrogs housed in the Wisconsin exhibit at the Milwaukee Zoo. Prospective screening of animals was initiated in September 1990, after two cases occurred in March and June 1990. Overall, of 47 animals that were housed in the exhibit from 1981 through its closure in 1995, 15 (31.9%) were diagnosed with mycobacterial infection. That includes 10 cases (of 24 animals; 40% prevalence) that occurred during the final 5 years, when all animals were actively being screened for infection. Infection was documented by culture for seven animals, histology for four animals, and both histology and culture for four animals. Species determination of nine of the 10 isolates revealed Mycobacterium marinum. Genetic fingerprinting of the eight available isolates using pulsed field gel electrophoresis (PFGE) showed that six animals (five snakes and one bullfrog) were infected with the same strain of M. marinum (strain A) and two snakes were infected with a second strain (strain B). Deaths of animals infected with strain A spanned 1992-1995, and for strain B 1990-1992. It is postulated that possible routes of transmission were inhalation of infected aerosols or ingestion of contaminated food, water, or fomites. These data suggest that in closed systems the presence of mycobacterial infection in one animal significantly increases the risk of infection for all animals. Moreover, individual pathogenic strains may persist for prolonged periods of time.

Biology and Diseases of Reptiles

“…An annual incidence of 0.1-0.5% of mycobacteriosis has been reported in well-managed reptile colonies; however, without adequate environmental control, the incidence can be as high as 31.9% (Hernandez-Divers et al, 2002;Maslow et al, 2002). Animals become infected via direct contact with contaminated water and food.…”

Systemic mixed infection in a brown caiman (Caiman crocodilus fuscus) caused by Mycobacterium szulgai and M. chelonae: a case report

“…The few reported cases of mycobacterial disease in reptiles have mostly indicated single organ involvement such as the lung, liver, spleen or epidermis (Maslow et al, 2002;Soldati et al, 2004;Noyes et al, 2007;Pavlik and Falkinham, 2009). Cases of farmed crocodiles with granulomatous lesions in the lungs, trachea and intestines have been reported (Youngprapakorn et al, 1994).…”

Amphibian Mycobacteriosis

“…Mycobacteria are fastidious and slow-growing bacteria, so it usually takes a few weeks to obtain a positive culture result. 2,6,7,12,16,20 In recent years, it has been possible to detect and identify Mycobacterium spp by molecular methods and a number of PCR-based techniques, increasing specificity and sensitivity and decreasing waiting time for results. Species identification and characterization can be made with restriction fragment length polymorphism (RFLP) analysis or other molecular techniques or with high-performance liquid chromatography (HPLC).…”

“…Species identification and characterization can be made with restriction fragment length polymorphism (RFLP) analysis or other molecular techniques or with high-performance liquid chromatography (HPLC). [2][3][4]6,7 Mycobacterium spp should be differentiated from other infectious agents such as ranavirus, Batrachochytrium dendrobatidis, Chlamydophila spp, Aeromonas hydrophila, and unspecific bacteria or fungi, as well as cutaneous neoplasms such as lymphosarcoma or histiocytoma. In bloated individuals, mycobacteriosis should be differentiated from other systemic infections; neoplasia; internal parasites; liver, renal, or heart failure; and, in adult females, reproductive tract disorders.…”

“…Taylor et al 21 Cannon et al 25 Ramakrishnan et al 10 Pranwichien et al 29 Ferreira et al, 6 Maslow et al, 7 18 Portaels et al 26 …”