University of Khartoum

Some Epidemiological and Zoonotic Aspects of Bovine Tuberculosis in Khartoum State, Sudan

Some Epidemiological and Zoonotic Aspects of Bovine Tuberculosis in Khartoum State, Sudan

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Title: Some Epidemiological and Zoonotic Aspects of Bovine Tuberculosis in Khartoum State, Sudan
Author: Abd EL Hakeem, Naglaa
Abstract: The present study was conducted in Khartoum State from February 2005 – February 2006 to determine the prevalence of bovine tuberculosis (BTB) and the risk factors associated with the occurrence of the disease on 35 randomly selected dairy herds containing 587 heads of cattle. Moreover, the zoonotic implication of bovine tuberculosis was also investigated. The methods applied were single intradermal comparative tuberculin test (SICTT) and a questionnaire to determine the risk factors. Assessment of the risk factors was based on comparisons of the reactivity of cattle to the tuberculin test. The overall prevalence of bovine TB in the investigated herds was 1.5%. Statistically, significant association was observed between poor body condition (P =0.001) and large herd size (P=0.027) on one side and prevalence of bovine tuberculosis on the other side. Additionally, among the negative animals, 1.9% showed reaction to avian PPD due to exposure to environmental mycobacteria. To study the zoonotic implications of BTB, 102 sputum samples were collected from patients admitted to the Tuberculosis Reference Laboratory, El Shaab Teaching Hospital and Abu Anga Hospital during the period January 2005 –January 2006. The 102 samples were stained by Ziehl-Neelsen and all revealed acid-alcohol-fast bacilli, 6 (5.9%) were fragmented acid-fast bacilli. Out of 102 sputum samples, 79 (77.5%) showed visible growth on Löwenstein-Jensen medium (LJ) when incubated aerobically at 37° C for up to 8 weeks. All the samples that showed fragmented acid-fast bacilli failed to grow on LJ medium. One sample showed visible growth after 6 days and was considered as rapid grower whereas 78 samples showed visible growth after 2 weeks and were considered as slow growers. The 79 mycobacterial isolates were tentatively differentiated by biochemical tests. One isolate was catalse positive and thus identified as mycobacterium other than tuberculosis (MOTT). Most of the isolates were nitrate positive and were resistant to thiophen-2-carboxylic acid hydrazide (TCH) and hence identified as Mycobacterium tuberculosis. Nested polymerase chain reaction (nPCR) was performed to differentiate the 79 mycobacterial isolates using the primer pair MTUB-f and MTUB- r for M. tuberculosis complex specific amplification of the 1,020-bp fragment of the gyrB gene. 77 (97.5%) isolate were positive for gyrB-PCR1 and thus identified as members of M. tuberculosis complex (MTBC) and 2 (2.6%) isolates were negative and identified as MOTT. The 77 MTBC isolates were further differentiated using a set of specific primers MTUB-756-Gf and MTUB-1450-Cr that allowed selective amplification of the gyrB fragment specific for M. tuberculosis. All the MTBC isolates 77 (100%) were positive for the gyrB-PCR2 and thus confirmed as M. tuberculosis strains. To evaluate the gyrB PCR-RFLP technique, the DNA polymorphisms in the 1,020-bp gyrB fragment for 7 M. tuberculosis strains confirmed by nPCR as well as 2 reference strains; M. tuberculosis H37Rv and M. bovis BCG were analyzed with the restriction enzyme Rsa1. All the M. tuberculosis isolates showed the typical M. tuberculosis specific Rsa1 RFLP patterns (100,360,560-bp) while 360 and 480-bp fragments were generated from M. bovis BCG.
URI: http://khartoumspace.uofk.edu/handle/123456789/8607
Date: 2015-04-08


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