Table 1.
Summary of key study characteristics of zTB in human observational studies
| Author (Publishing Year) | Objective of study | Assess livestock exposure/ raw dairy? | Location of Study (Country) | Human case inclusion | Study Design | Livestock testing? | Human Sample Size | % positive for zTB as total of all samples | % positive for zTB as total of all Mycobacterium positive samples |
|---|---|---|---|---|---|---|---|---|---|
| Ameni et al. (2013) | Investigate the transmission of MTC between cattle and their owners in Central Ethiopia | Yes | Ethiopia | Farmers: cases clinically diagnosed TB; controls did not have TB history in the last decade | Case‐control | Herds of AFB‐positive and TB‐free households CIDT tested; strong reactors slaughtered and necropsied; TB lesions cultured | 257; 146 cases; 141 controls | 0% | n/a |
| Gumi et al. (2012) | Assess presence of M. bovis among human TB patients; describe mycobacterial strains circulating in SE Ethiopian pastoralists and livestock | No | Ethiopia | Clinically diagnosed with pulmonary TB or TB lymphadenitis | Cross‐sectional | Cattle, goats, camels with suspected TB lesions at abattoirs | 292 | 1.02% (3/292) | 1.6% (3/183) AFB positive |
| Malama et al. (2014) | Molecular identification of M. bovis in humans and cattle; determine zoonotic significance in Namwala district of Zambia | Yes | Zambia | Clinically suspected of pulmonary TB | Cross‐sectional | Slaughtered cattle at 2 abattoirs | 100 | 2% (2/100) | 5.6% (2/36) total MTC |
| Mengistu, Enquselassie, Mulatu, Hailu, & Beyene, (2015) | Investigate/ determine the prevalence of BTB and see possible role of cattle in the epidemiology of human TB and isolate MTC species in the Wollo Zone, Amhara National Regional State | Yes | Ethiopia | Persons with chronic cough of 2 + weeks, owned cattle, not under treatment for TB, and > 15 years of age | Cross‐sectional | Cattle tested using CIDT, no further diagnostics for reactors | 124 | 0% | n/a |
| Milian‐Suazo et al. (2010) | Compare spoligotypes from humans and cattle from the same geographic area to better understand the epidemiology of TB and the link between cattle and human cases of TB | Yes | Mexico | TB symptomatic patients, or dairy farm workers & local slaughterhouse workers | Cross‐sectional | Cattle from a local slaughterhouse with suspect lesions with cultured | 552 | 6.2% (34/552) | n/a |
| Nuru et al. (2017) | Investigate the transmission of zTB between cattle and its owners in smallholder farms in northwestern Ethiopia | Yes | Ethiopia | Clinically diagnosed TBLN patients | Cross‐sectional | CIDT on cattle owned by TB patients and on TB‐free households | 70 | 2.9% (2/70) | 5% (2/40) |
| Prasad et al. (2005) | Utilize PCR‐RFLP and nested‐PCR to differentiate and detect M. bovis and M. tuberculosis and mixed infections in human and cattle extra‐pulmonary tuberculosis samples | No | India | Patients clinically suspected of TB | Cross‐sectional | Cattle clinically ill and clinically normal animals tested | 331 | 10.3% (34/331); 8.7% (29/331) mixed M. bovis and M. tb infection | 29.6% (34/115); 25.2% (29/115) mixed M. bovis and M. tb infection |
| Rahman et al. (2015) | Evaluate PCR‐based diagnostic test specific for M. bovis for testing bovine and human bio samples for bTB and to identify potential risk factors for its human transmission | Yes | Bangladesh | Chest radiograph and direct smear microscopy‐positive TB patients | Cross‐sectional | 300 bovine milk samples: 200 from healthy animals and 100 from debilitated cows | 90 | 6.7% (6/90) | n/a |
| Firdessa et al. (2013) | Explore public health risk for bovine TB in Ethiopia using molecular typing to characterize isolates from TBLN and pulmonary TB patients; define role of M. bovis in human TB | Yes | Ethiopia | Patients suspected of TBLN or pulmonary TB | Cross‐sectional | No | 2,151 | n/a | 0.4% (4/964) AFB positive |
| Kazwala et al. (2001) | Determine the involvement of M. bovis in TB cases presenting at TB clinics in rural areas in the study area. | Yes‐ livestock keeping | Tanzania | Clinically diagnosed pulmonary or extra‐pulmonary TB | Cross‐sectional | No | 149 | 4.7% (7/149) | 15.9% (7/44) Mycobacteria culture positive |
| Khattak et al. (2016) | Determine the burden of active pulmonary TB caused by M. bovis in abattoir workers, butchers, veterinarians, livestock farmers and vet assistants and document associated risk factors | Yes | Pakistan | Government abattoir workers, butchers, farmers, vet assistants and veterinarians with chronic cough with sputum or blood | Cross‐sectional | No | 103 | 4.9% (5/103) | n/a |
| Laniado‐Laborin et al. (2014) | Determine the prevalence of M. bovis human disease among patients referred to the Tuberculosis Laboratory of the Tijuana General Hospital in Baja California, Mexico and to characterize the clinical isolates molecularly | No | Mexico | Culture‐positive cases of TB | Cross‐sectional | No | 2,699 | 1.0% (27/2699) | 4.5% (27/600) |
| Oloya et al. (2008) | Isolate and characterize mycobacteria causing cervical lymphadenitis in patients in the transhumant areas of Karamoja, Uganda | No | Uganda | Diagnosed with cervical lymphadenitis | Cross‐sectional | No | 43 | 7% (3/43) | 12.5% (3/24) |
| Portillo‐Gomez and Sosa‐Iglesias (2011) | To identify isolates of Mycobacterium bovis in humans and cattle by PCR, and establish the clinical and epidemiological importance of ZTB in humans | Yes | Mexico | Clinically diagnosed pulmonary or extra‐pulmonary TB | Cross‐sectional | No | 124 | 28% (35/124) | n/a |
| Viegas et al. (2015) | Explore the public health risk for bovine TB in Maputo, the capital of Mozambique, by characterizing the isolates from TBLN case during one year in the Pathology Service of Maputo Central Hospital | No | Mozambique | Clinically suspected TBLN | Cross‐sectional | No | 110 | 0% | n/a |
Abbreviations: AFB, acid‐fast bacilli; bTB, bovine tuberculosis; CIDT, comparative intradermal tuberculin test; M. tb, M. tuberculosis; MTC, Mycobacterium tuberculosis complex; PCR, polymerase chain reaction; PCR‐ RFLP, polymerase chain reaction ‐ restriction fragment length polymorphism.