Prevalence and Pathobiology of Tuberculosis

Introduction

Tuberculosis caused by M. bovis has been shown to infect all species of deer so far studied (Clifton-Hadley and Wilesmith, 1991). Lesions typical of Tb have been found in a zoo park in Taiwan in sambar, fallow and sika deer (Wu, 1986). Tuberculosis in deer caused by M. tuberculosis has been found in park deer in India (Singh et al., 1986) and in Indian zoos (Shah et al., 1986). In England, relatively high prevalence of bovine tuberculosis in deer has been reported, which acts as one of the sources of infection to cattle (Ward et al., 2009).

Deer occupy an extensive range of habitats worldwide and there has been a long history of human intervention in the management of deer over the past 50 000 years (Fletcher, 1992). Attempts to manage the animals as a domesticated species have been undertaken for over 5000 years, and farmed deer are now found in many countries. Deer are found naturally in the wild in most continents, and selected populations have been held in game parks, zoological parks and gardens across the world.

The disease has been found sporadically in wild deer (McDiarmid, 1960) and more frequently as a spreading infection within farmed deer herds. There have been recorded cases of Tb in wild white tailed deer (Odocoileus virginianus) in America (Levine, 1934), axis deer (Axis axis) in Hawaii, (Sawa et al., 1974), fallow deer (Dama dama) in Ireland (Wilson and Harrington, 1976), sika deer (Cervus nippon) in Ireland (Dodd, 1984) and roe deer (Capreolus capreolus) in England (Gunning, 1985). The advent of deer farming has amplified the incidence of Tb in cervidae. Bovine tuberculosis is one of the most important zoonoses and is a disease that is prevalent in livestock in Pakistan (Javed et al., 2009, 2010a, b). Infected wild deer are a possible source of contamination for domestic livestock (Stumpff,1982). Captive deer in zoos or wild life parks also act as a significant reservoir of Tb whenused as foundation stock for deer farming (Towar et al., 1965).

Gross lesions

Tuberculosis granulomas in the lymph nodes of the head, lungs, intestine and carcass. These have usually a well-defined capsule enclosing a caseous mass with a calcified centre. They are usually yellow in colour in cattle, white in buffaloes and greyish white in other animals. Active lesions may have a reddened periphery and caseous mass in the centre of a lymph node. Inactive lesions may be calcified and encapsulated. Nodules on the pleura and peritoneum. Lesions in the lungs, liver, spleen, kidney. Bronchopneumonia. Firmer and enlarged udder, particularly rear quarters. Lesions in the meninges, bone marrow and joints.

Prevalence:

TB caused by infection with M. bovis has one of the broadest host ranges of all known pathogens and the organism has been isolated from most domesticated and wild animals (O'Reilly & Daborn, 1995). It has been isolated from a wide range of deer species. Understanding of the prevalence in deer in the UK is an important step in understanding the epidemiological in role transmission/ maintenance of bovine tuberculosis (Gowtage et al., 2009). In the USA, the role of deer in spreading bTB to cattle has been identified (Schmitt et al., 2002; Wilkins et al., 2003), and is also suspected in Spain (Aranaz et al., 2004). In England, relatively high prevalence of bovine tuberculosis in deer has been reported, which acts as one of the sources of infection to cattle (Ward et al., 2009). In England, relatively high prevalence of bovine tuberculosis in deer has been reported, which acts as one of the sources of infection to cattle (Ward et al., 2009). TB in New Zealand's foundation deer farming stock arose largely from endemic infection present in captured wild deer, which became infected through exposure to TB-infected cattle and brushtailed possums (Trichosurus vulpecula) (Morris et al., 1994). Considering the high levels (>50%) of cattle infected with TB in Europe and North America in the early 1900s. While endemic TB in wild deer is uncommon, it has been diagnosed in populations in Canada (Tessaro, 1986), Great Britain (Rose, 1987), Hungary (Zomborszky et al., 1995), Ireland (Dodd, 1984), New Zealand (Mackintosh & Beatson, 1985), North America (Levine, 1934; Sawa et al., 1974; Wagner, 1993) and Switzerland (Bouvier, 1957). Recently, there has been a widespread and persistent outbreak of tuberculosis in free-range white-tailed deer (Odocoileus virginianus) in Michigan, USA (Schmitt et al., 1997).

Work on Tuberculosis in Bovines:

Rapid in vitro cellular assay for bovine tuberculosis based on the production of 'Y interferon, HIV/AIDS-ASSOCIATED HUMAN TB DUE TO M. BOVIS,A sandwich enzyme immunoassay for bovine interferon?and its use for the detection of tuberculosis in cattle, Correlation of ESAT-6-Specific Gamma Interferon Production with Pathology in Cattle following Mycobacterium bovis BCG Vaccination against Experimental Bovine Tuberculosis, Use of Synthetic Peptides Derived from the Antigens ESAT-6 and CFP-10 for Differential Diagnosis of Bovine Tuberculosis in Cattle surveillance records on cattle slaughtered and suggestive tuberculosis lesions from cattle slaughtered annually from 2007-2012 in Jos abattoir, Plateau State.

Work on Tuberculosis in Wild Animal: The single intradermal tuberculin test, BLOOD TESTS FOR TB DIAGNOSIS, MOLECULAR TYPING OF M. BOVIS ISOLATES, Mycobacterial identification culture methods, PCR amplification, Sequence analysis of PCR products amplified from M. bovis and M. tuberculosis.

The prevalence of disease in zoo animals is a direct threat to people working in the zoo and the visitors. It has been emphasized that the TB testing in zoos may be carried out regularly, though no standard protocols are currently in place. Skin testing with tuberculin is still considered as an efficient test for various animal species and is in use in wild and zoo animals. In Pakistan, no work could be traced indicating prevalence of the disease in wild or zoo animals.

Methodology: 1-Tag deer,collect blood and perform Bovigam assay. The BOVIGAM?® test is a blood-based in vitro laboratory test for bovine tuberculosis. It is based on the detection of cell-mediated immune response to infection with Mycobacterium bovis. The BOVIGAM test involves two stages. In the first stage, blood samples are incubated overnight with antigens, such as tuberculin purified protein derivative (PPD) or the newly developed "peptide cocktails", to stimulate lymphocytes to produce IFN-??. In the second stage, IFN-?? in the plasma supernatants of each blood aliquot is determined using a sandwich ELISA. IFN-?? present in the sample binds to anti-bovine IFN-?? monoclonal antibodies on a solid support and is visualized with a second anti-IFN-?? antibody labeled with an enzyme that generates a color signal. Color development is proportional to the amount of bound IFN-??.

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