Pathological, Bacteriological and Molecular Characteristics of Tuberculosis in Domestic Ruminants and Camels in South Darfur State, Sudan

Abstract

Tuberculosis is an infectious, chronic bacterial disease in wide range of domestic and wild animals and humans. The literature of animals tuberculosis is meager and the true picture of the epidemiology of the disease in different parts of the Sudan is still not clear. Thence this study was designed in an attempt to delineate the pathology, bacteriology and molecular characterization of TB in slaughtered cattle, goats, sheep and camels in South Darfur State during the period October 2015 to December 2016 to establish a data base, which expected to help in the formulation of strategic control measures. Tuberculous lesions were found in 358 (10.7%) cattle, 119 (3.7%) goats, 93 (2.9%) sheep and 17 (1.4%) camels, infected animals had generalized or localized tuberculosis excepting camels which had only localized tuberculosis, mainly in the lungs, lymph nodes, liver, spleen, rumen and/or kidneys and ribs. Tuberculous lesions were collected either in buffered neutral formalin for histopathology or in ice boxes for microscopy and bacteriology. Grossly, in cattle, goats, sheep and camels the tubercles appearance as embedded in the parenchyma and sometimes bulging on the surface of the infected organs with thick fibrous capsule in yellow, or pale yellowish, or white, or gray or light grey color in variable in sizes, containing caseous, or caseo-calcified, or calcified, or sticky or gritty materials. In general cases, the granulomatous sections showed central caseous necrosis areas in round or oval or irregular shape, with or without moderate central calcification, surrounded by moderate epithelioid cells and langhan's type giant cells with partially or completely fibrous connective tissues and infiltrated by lymphocytes and plasma cells. Furthermore, randomly invasive of calcium in black color were observed in necrotic areas and acid fast bacilli (AFB) were seen scattered randomly in necrotic areas or inside macrophages or giant cells. Samples with microscopic examination showed 87.3% cattle samples, 91.6% goats samples, 91.8% sheep samples and 73.4% camels samples were positive for acid fast bacilli. A total samples of 1400 (18.5%) cattle, 479 (16.1%) goats, 383 (16.2%) sheep and 64 (23.4%) camels were grew on LJ medium and 259 Mycobacterium from cattle, 77 from goats, 62 from sheep and 15 from camels were isolated and identified by biochemical and molecular techniques. Out of them, in cattle 179 were identified as M. bovis and 15 were identified M. tuberculosis, while in camels 11 were identified as M. bovis and 4 were identified M. tuberculosis. Furthermore, in goats 62 were identified as M. bovis and 7 were identified M. v tuberculosis, Whereas in sheep 46 were identified as M. bovis. The sequencing of 45 DNA products of M. bovis were confirmed as M. bovis BCG strain and 5 DNA products of M. tuberculosis were confirmed M. tuberculosis H37Ra strain. These study concluded that the occurrence of cattle tuberculosis is on the increase during the years ago and more goats, sheep and camels in the region are getting exposed. In addition, Ambboror's cattle and sheep, and Baggara's goats are the reservoirs of TB among the livestock in the region and respiratory pathway is the most site of infection in animals. To the best of our knowledge, this is the first isolate of M. tuberculosis from goats and camels and detects Mycobacterium bovis BCG strain M. tuberculosis H37Ra strain in the Sudan. Further studies are needed to determinate the occurrence of TB in the live animals and complete genome sequencing of isolated Mycobacterium.