Browsing by Author "Gizat Almaw"

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    Across- Sectional Study of Bovine Mastitis in and around Bahirdar and Antibiotic Resistance Patterns of Major Pathogens
    (Addis Ababa University Faculty Of Veterinary Medicine, 2004-06) Gizat Almaw; Ademe Zerihun
    Three hundred fi fty one (J 95 local zebu and 156 Holstein x Local Zebu) lactating cows of smallholder private farms in Bahir Dar milk shed were examined from September, 2003 to March, 2004 (0 determine mastitis prevalence, isolate pathogens involved, evaluate the antibiotic susceptibility profi les and [0 evaluate somatic cell count in identifying intramammary infections. Clinical prevalence was detemlined through examination of abnomlalities of milk, udder or cow. Cal ifornia mastitis test (CMT) and culture were used for subclinical mastitis determ ination. Agar disc di ffusion was used for antibiotic susceptibility test. Somatic cell count was conducted following standard procedures described In International Dairy Federdtion for enumeration of cells with direct Microscopic method. Clinical prevalence at cow level was 3.9% in crossbreds and nonc in local zebu breeds. Subclinical mastitis at cow level based on CMT was high (34.4%) in crossbreds compared to indigenous zebu (17.9%) (p < 0.05). Quarter subclinical prevalence based on eMT was 17.90% and 4.95% for crossbreds and local zebu. respectively. Among potential risk factors considered, stage of lactation, parity and breed were found 10 afTecI the occurrence of mastitis significantly (p < 0.05). The pathogens isolated from mastitic milk were coagulase negalive staphylococci (eNS), s. aureus. Srr. agalacliae. Sir dysgalactiae. Srr. uberis. Micrococcus species, C. bovls. A. pyogefls, B. cereus, and S. illtermedius. Among these, the most frequent isolates were eNS (49.6% of the 10lal isolates). S. alirellS (17.9%), Srr. agalacliae (8.2%) and SIr dysgalacliae (6:7%). Seven antibiotics including sulfi soxazole. tetracycline, erythromycin. oxacillin, chloramphenicol, cJindamycin, and streptomycin were tested on 81 isolates. Except for streptomycin, all isolates \\ere sensitive to all antibiotics. All isolates were most sensitive 10 sulfisoxazole. Staphylococcw; allreus was susceptible to all drugs except streptomycin. SllIphylococcus Ollreus was 91.7% susceptible to oxacillin, however, CNS were less susceptible (68.2%) ill vilro. To evaluate somatic cell count (SeC) in identifying imramamary infection for crossbreds. 10 cutoff poims between 100000 cellsl ml and 300000 celJSJml were evaluated for their sensllivity and speci-ficity in comparison with cultural results. Similarly, cutoff points between 80000 cell ml and "250000 cell ml were taken for local zebu breeds. The sensitivity for
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    Epidemiology and Molecular Characterization of Mycobacterium Bovis in Humans and Cattle and Assessment of its Zoonotic Importance in Central Ethiopia
    (Addis Ababa University, 2021-11) Gizat Almaw; Mihret Adane ; Abebe Tamrat
    Mycobacterium bovis (M. bovis) is a member of the Mycobacterium tuberculosis complex (MTBC) and causes tuberculosis in humans (zoonotic tuberculosis-zTB) and animals, mainly in cattle (bovine tuberculosis-bTB). There were limited studies on zTB in Ethiopia but also a reliable estimate of bTB prevalence in cattle in central Ethiopia is missing. In addition no wholegenome sequencing (WGS) based M .bovis studies had been performed in Ethiopia before this study. Also, there has been a limited effort in search for an alternative diagnostic method to culture to detect M. bovis in clinical specimens. Therefore, due to these research gaps, this study, which combined bTB and zTB, was conducted from 2018 to 2021 in central Ethiopia (Addis Ababa, Sebeta, Holeta, Sululta, Sendafa and Bishoftu) with the objective of generating epidemiological and molecular data to update our understanding on bTB/zTB. The bTB study in cattle involved a cross sectional one-stage cluster sampling survey of dairy farms in central Ethiopia using tuberculin skin testing and the collection of additional data by questionnaire to estimate the prevalence of bTB and identify potential risk factors contributing to Btb transmission. For the zTB part, surveillance of TB in humans was carried out among individuals working in bTB infected dairy farms, patients presented at selected health centers, and exposure to risk factors was assessed using questionnaire. From consenting TB suspected individuals, demographic and clinical information was collected by questionnaire. Sputum and Fine Needle Aspirates (FNA) samples were collected from suspected cases. In addition, isolation of M. bovis was done from raw milk collected from tuberculin skin test positive cows and from cattle tissue lesions. The genetic diversity of M. bovis isolates was examined using spoligotyping and whole genome sequencing (WGS) analysis. Furthermore, in this study the performance of a TaqMan real time PCR (RT-PCR) assay as an alternative diagnostic method to culture was evaluated. Two hundred ninety-nine (n=299) dairy herds in the six study areas were randomly selected, from which 5,675 cattle were tested. The overall prevalence of bTB after standardisation for herd-size in the population was 54.4% (95% CI 48.7-60%) at the herd level, and it was 24.5% (95% CI 23.3-25.8) at the individual animal level. A Generalized Linear Mixed Model (GLMM) was used to explore risk factors association with bTB status. We found that herd size, animal age, bTB history at farm, and breed were significant risk factors. With regard to zTB, among 110 DFWs in 73 bTB infected dairy farms, 41 had at least one of the symptoms that are typical forTB. Three DFWs had swollen nodes at their neck, a symptom typical for TB lymphadenitis. In assessment of risk factors: raw milk consumption was practiced by more than two thirds of theDFWs with symptoms of TB (68.2%) and over half of DFWs with symptoms did not think TBcould be transmitted via raw milk consumption. Overall in the surveillance of zTB (active and passive), a total of 167 specimens (sputum=131; FNA=36) were collected from 161 TB suspected individuals for the isolation of M. bovis. Of these processed specimens, three samples with M. bovis were detected in total (1.8%, n=167). And of these three, one M. bovis isolate was sequenced and the genotype was spoligotype SB1476 which was previously reported from cattlein Ethiopia suggesting possible zoonotic transmission. With regard to isolation and characterization of M. bovis from cattle, out of 827 cattle (abattoirs and dairy farms), 76 of them(9.2%) had tuberculous lesion. From these tuberculous lesions, 62 isolates (n=137 samples) from42 animals were confirmed to be M. bovis. Similarly out of 975 milking cows which were tuberculin skin test positive (37.8%, n=2582), 490 composite raw milk samples were collectedand of these 11 (2.2%) yield M. bovis isolates showing evidence that raw milk is not safe and can be a source of infection for human TB due to M. bovis. The genetic diversity of 74 M. bovisisolates (one being a human isolate) was assessed and ten different spoligotypes were recorded. In cattle spoligotype SB1176 was the most prevalent type (n=31, 44.3%) followed by SB0133(n=11, 15.7%). Our WGS analysis with a total of 55 M. bovis isolates sequenced (one being ahuman isolate) showed three clonal complexes clearly segregating in the phylogeny: African 2(Af2; n=47), European 3 (Eu3; n=7) and Unknown8 (n=1). In addition, the present study reported for the first time clonal complex European 3 (Eu3) from Ethiopia. With regard toTaqMan assay performance evaluation - the assay performance on 440 clinical samples was variable for different specimens and overall performed well for sputum samples for all targets. In conclusion, this study recorded high prevalence of bTB in dairy cattle in central Ethiopia. M.bovis prevalence in humans in central Ethiopia was low; however, further investigation is neededin all regions at national level given bTB is endemic in cattle in Ethiopia. Knowledge gap onbTB and M. bovis isolation from milk, showed that there is a clear potential for zoonotic transmission and needs further investigation. The TaqMan RT-PCR assay is a promising methodology for the diagnosis of zTB and bTB, but with further validation works needed usingdifferent targets and specimens