Abstract
During recent decades, cases positive to Mycobacterium pinnipedii in captive animals have increasingly been reported. This increasing presence is most probably due to the fact that more information is available after the EAAM workshop held in Duisburg (Germany) in 2009.1 More readily available tests have been produced and more animals have been tested.
Currently for pinnipeds, 3 different serological tests2 have been developed to detect the infection ante mortem. These do not validate species specificity; 3 direct tests (specific stain Acid fast bacteria, PCR and culture of different samples) for M. pinnipedii (part of Mycobacterium tuberculosis complex, MTC) are currently used and CT scan has apparently proven to be the most reliable diagnostic tools for animals with calcified lesions.
Animal 1: adult, 1997 captive born, male, kept at Gardaland with 3 other animals, was tested yearly since 2009 for MTC with Elephant TB-STAT-PACK (RT test) and always resulted negative until March 4th 2012, when PCR, AFB and culture on sputum and stool also resulted positive, although to an atypical Mycobacterium. The 3 other Patagonian sea lions tested yearly had negative results for RT test and AFB, PCR and culture on sputum and feces up until 2013.
Animal 2: adult male, wild born (estimated 22 years old) was confiscated by Italian authorities and Gardaland was given custody in March 2012. Animal 2 was always kept in quarantine and completely isolated from other animals. The animal was tested with RT test upon arrival on the 30th March and resulted positive.
Dual Path Platform VetTB (DPP) was also performed on both animals and resulted positive. The animals started treatment with a triple combination of antibiotics, (Rinfampicin 7mg/kg PO SID; Isoniazide 5 mg/kg PO SID; Ethambutol 15 mg/kg PO SID), although the animals were completely asymptomatic.
After one week of treatment both animals showed an abnormal appetite. Animal 2 started to refuse part of his daily diet and during the 3rd week of antibiotic treatment he completely stopped eating. Animal 2 died on the 26th day of treatment. Positive animals were tested every 2 months with PCR, AFB and culture on sputum, feces, urine and saliva and only animal 1 always resulted positive for an atypical Mycobacterium.
The animal was transported to University of Padua and a full necropsy was performed within less than 20 hours. All lymph nodes (among all other tissues) were sampled and tested for Mycobacterium spp. From tests performed and results received so far, the animal appeared to be negative. Necropsy revealed that the animal died from congestive cardiac failure, associated with acute hepatic necrosis.
Considering the evolution of the clinical situation of the animal, negativity to MTC and hepatic degeneration noticed at necropsy, some considerations and questions arise: 1) considering the lack of pharmacokinetic studies for most of the drugs used on pinnipeds, is it possible that the current dosages used for the treatment are too high for older animals?; 2) what is the impact of treatment on gastrointestinal function and general wellbeing?; and 3) Is it possible the RT test and DPP test cross react with other mycobacterium, more than the MTC?
Acknowledgements
The authors wish to thank Dr. Jurczynski, Dr. Lecu, Dr. Garcia Parraga and Dr. Greenwood for their help with technical support.
* Presenting author
LITERATURED CITED
1. EAAM workshop. Mycobacterium pinnipedii. 2009. Duisburg Zoo, Germany
2. Jurczynski, K, Lyashchenko, KP, Scharpegge, J, Fluegger, M, Lacave, G, Moser, I, Tortschanoff, S and Greenwald, R. 2012. Use of Multiple Diagnostic Tests to Detect Mycobacterium pinnipedii Infections in a Large Group of South American Sea Lions (Otaria flavescens). Aquatic Mammals, 38: 43–55