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Subjects:
Infectious Diseases
Mycobacterium bovis is the etiologic agent of bovine tuberculosis (BTB), a serious infectious disease in both humans and animals. BTB is a zoonotic disease primarily affecting cattle and occasionally humans infected through close contact with infected hosts or the consumption of unpasteurized dairy products. Zoonotic tuberculosis is strongly associated with poverty and poor hygiene, and low- and middle-income countries bear the brunt of the disease. The epidemiologic trends of M. bovis infection varied across the MENA countries, likely influenced by the population size, characteristics of the targeted population, the geographical region, and the rigor of the adopted diagnostic tools and investigation methods. Additionally, the heterogeneity of BTB prevalence has been also associated with other factors such as Bacille Calmette-Guérin (BCG) vaccination status, the consumption of unpasteurized dairy products, and the efficiency of national surveillance programs and BTB control measures.
- Mycobacterium bovis
- one health
- epidemiology
- antimicrobial resistance
- MENA region
1. Mycobacterium bovis in Animals
Cases of Bovine tuberculosis (BTB) were noted from both pulmonary and extrapulmonary sites in animals (Table 1) and humans (Table 2). In animals, active BTB was usually reported in cattle and buffalo; however, uncommon cases were described among other types of animals. Specifically, M. bovis was reported in a cat and a mongoose in Turkey [16] and Egypt [17], respectively. A deer infected with BTB was also observed in Iran [18], while M. bovis was detected in camels and pigs in Egypt [19,20].
Several risk factors for BTB appear to play an essential role in the spread of M. bovis among animals in the MENA region. Age, gender, animal body condition, immune suppression, crowding, cross-species transmission, grazing practices, feeding system, environment or weather, and physiological and pathological variations are potential factors contributing to the dissemination of zoonotic M. bovis. Female animals are at a greater risk of BTB than males due to lactation, gestation, and parturition [21,22]. Cross-species transmission between goats and cattle and between buffalo and cattle was associated with sharing of drinking and grazing locations in Algeria [23] and Iran, respectively [24,25]. Furthermore, uncontrolled animal migrations and trade within and across countries were noted as key drivers for BTB transmission [26]. People working closely with livestock, particularly dairy cattle (e.g., farmers, veterinarians, slaughterhouse workers) or with wildlife were more susceptible to M. bovis infections [27].
The World Organization for Animal Health (WOAH) has categorized the tuberculin skin test (TST) as a primary screening test for tuberculosis in cattle [28]. TST is the most frequently used test for the diagnosis of BTB in cattle. Typically, TST’s discriminatory power could be improved by combining it with the interferon-gamma release assay (IGRA) which improves both sensitivity and specificity [29]. M. bovis ELISA tests are also available, allowing the detection of antibodies against zoonotic tuberculosis in cattle serum and plasma samples [30]. Although the ELISA assay is not yet recognized as a standard test for tuberculosis in cattle, it has been approved by the WOAH as being complementary to the TST in cattle. It should be noted that when using these diagnostic approaches, it is difficult to distinguish between vaccinated and infected animals and latent and active infections [31]. However, based on these assays, the prevalence of BTB among cattle varied significantly according to the population size and country in the MENA region. In large studies, the prevalence was relatively low, ranging between 0.1 [32] and 16.4% [33] in Egypt, 4.4 [34] and 24.2% [35] in Iraq, 3.5% [36] in Algeria, and 1.4% [37] in Turkey. In contrast, a higher prevalence was reported in studies with small population sizes, ranging from 22.2% [38] to 82.6% [39] in Egypt, 75% [40] in Iraq, and 48% [41] in Tunisia (Table 1). The trends in the prevalence of BTB also changed over time. In Egypt, Iran, Iraq, Morocco and Sudan, the prevalence of infection among cattle varied between 0.2% [42] and 4.3% [43], 8.5% [44] and 26.3% [45], 1.3% [46] and 10.2% [47], 1.7% [48] and 51.3% [49] and 0.2% [50] and 20.8% [51] over the last two decades, respectively.
Regarding M. bovis in milk samples collected in the MENA region, most studies reported a relatively low prevalence, ranging from 0.004% [33] to 10.2% [52]. Notably, Iraq and Tunisia led the list of M. bovis prevalence in milk samples (Table 1). Using the ELISA assay, a higher infection risk (20.2%) among lactating cows was found in rural areas of Waist and Dhi-Qar provinces, Iraq [53]. Despite the challenges in detection of M. bovis in milk samples, available data from the MENA region confirmed that this matrix represents an important source of zoonotic tuberculosis, because milk (1) is still commonly consumed raw, without pasteurization, in many rural regions and (2) is widely used in the manufacturing of popular dairy products such as cheese and yogurt [54]. Taken together, available data underlined the existence of animal and food sources as well as zoonotic risks that escaped common tuberculosis control measures in many MENA countries. Therefore, there is a strong need to increase awareness on food safety and hygiene and strengthen active surveillance programs in food animals and their products [55]. To prevent the further dissemination of BTB infection, effective approaches must be adopted, including early identification, adequate therapy, and contact tracing [56]. Currently, BTB control mostly relies on slaughter policy, postmortem inspection, and slaughterhouse surveillance [57], which do not even address preharvest risks.
Table 1. Burden of Mycobacterium bovis in animals in the MENA region.
| Country | Study Period | Study Design | Population (N) | Tuberculosis (TST, IGRA, ELISA) † | Samples (N) for Active Tuberculosis Testing | Health Status | BTB Identification (Culture, PCR) | Prevalence ¶ of BTB (%) | Typing Method | References |
|---|---|---|---|---|---|---|---|---|---|---|
| Algeria | 2007 | Cross-sectional | Cattle (7250) | Tissue (260) | Slaughtered | Culture | 88 (1.2%) | Spoligotyping; MIRU-VNTR | [31] | |
| 2017 | Cross-sectional | Cattle (3848) | Tissue (3848) | Slaughtered | Culture; PCR | 59 (1.5%) | Spoligotyping; MIRU-VNTR | [58] | ||
| 2017–2018 | Cross-sectional | Cattle (928) | Tissue (928) | Slaughtered | Culture; PCR | 13 (1.4%) | WGS | [21] | ||
| 2017–2019 | Cross-sectional | Cattle (3546) | Tissue (3546) | Slaughtered | Culture; PCR | 174 (4.9%) | Spoligotyping | [23] | ||
| 2018–2019 | Cross-sectional | Cattle (516) | 18 (3.5%) | Live | ND | [36] | ||||
| Egypt | 2008–2010 | Cross-sectional | Cattle (3255) Buffalo (2950) | Cattle: 105 (3.2%) Buffalo: 85 (2.9%) |
Tissue (190) Milk (520) Blood (190) |
Slaughtered | Culture; PCR | 16 (0.2%) | [59] | |
| 2008–2010 | Cross-sectional | Cattle (1180) | 29 (2.5%) | Tissue (29) | Slaughtered | Culture; PCR | 20 (1.7%) | [60] | ||
| 2010–2011 | Cross-sectional | Cattle (3347) | 32 (1%) | Tissue (32) | Live and slaughtered | Culture; PCR | 21 (0.6%) | [61] | ||
| 2013 | Cross-sectional | Cattle | Milk (100) | Healthy | Culture; PCR | 1 (1%) | [62] | |||
| 2014–2015 | Cross-sectional | Cattle (2935) | 63 (2.2%) | Tissue (56) | Slaughtered | Culture | 39 (1.3%) | [63] | ||
| 2008 * | Cross-sectional | Camels (704) | 9 (1.27%) | Tissue (29) | Slaughtered | Culture | 5 (0.7%) | [64] | ||
| 2009 * | Cross-sectional | Cattle (46) | 38 (82.6%) | Milk (23) | Sick | Culture | 1 (2.1%) | [39] | ||
| 2014 * | Cross-sectional | Cattle (422) Buffalo (480) | Cattle: 9 (2.1%) Buffalo: 27 (5.62%) |
Tissue (36) | Slaughtered | Culture | 25 (2.8%) | IS6110 RFLP | [65] | |
| 2015 * | Cross-sectional | Cows (420) | 8 (1.9%) | Milk (8) | Healthy | Culture; PCR | 1 (0.2%) | [42] | ||
| 2018 * | Cross-sectional | Sheep (18) | 4 (22.2%) | Tissue (18) | Slaughtered | Culture; PCR | 15 (83.3%) | [38] | ||
| 2009–2013 | Longitudinal | Cows and buffalos (1,186,772) | 1225 (0.1%) | Blood (14) Tissue (34) |
Live and slaughtered | Culture; PCR | 29 (0.002%) | [32] | ||
| 2016–2019 | Cross-sectional | Cattle (2200) Buffalo (1500) | Tissue | Culture; PCR | Cattle 36 (1.6%) Buffalo 18 (1.2%) |
[66] | ||||
| 2018 | Cross-sectional | Cattle (2650) | 63 (2.4%) | Tissue (63) | Healthy | Culture | 47 (1.8%) | [67] | ||
| 2018–2019 | Cross-sectional | Cattle (569) Buffalo (181) | Tissue (30) | Slaughtered | Culture; PCR | 9 (1.2%) | [68] | |||
| 2011–2016 | Cross-sectional | Cattle (1570) Buffalo (530) | 74 (3.5%) | Tissue (74) | Slaughtered | PCR | 61 (2.9%) | [69] | ||
| 2017 | Cross-sectional | Cattle (2710) | 215 (7.9%) | Milk (245) | Live | Culture; PCR | 68 (2.5%) | [70] | ||
| 2014 * | Cross-sectional | Cattle (300) | 53 (17.6%) | Blood (65) | Live and slaughtered | Culture; PCR | 13 (4.3%) | [43] | ||
| 2011 | Case report | Mongoose (1) | Tissue (1) | Slaughtered | Culture; PCR | 1 | [17] | |||
| 2015–2017 | Longitudinal | Camels (10,903) | 184 (1.7%) | Tissue (184) | Live and slaughtered | Culture; PCR | 112 (1.0%) | [19] | ||
| 2018–2019 | Cross-sectional | Cattle (1464) | Milk (1285); Lymph nodes (179) | Live and slaughtered | Culture; PCR | 127 (8.6%) | [71] | |||
| 2011–2016 | Cross-sectional | Cattle and Buffalo (2100) | 81 (3.8%) | Tissue | Live | Culture; PCR | 61 (2.9%) | MIRU-VNTR | [26] | |
| 2016 * | Cross-sectional | Cattle and Buffalo (6000) | 79 (1.3%) | Tissue | Live and slaughtered | Culture; PCR | 23 (0.4%) | [72] | ||
| 2004–2005 | Cross-sectional | Pigs (745) | Tissue | Slaughtered | Culture; PCR | 12 (1.6%) | [20] | |||
| 2019 * | Cross-sectional | Cattle (2600) | 47 (1.8%) | Tissue | Healthy | Culture; PCR | 40 (1.5%) | [73] | ||
| 2006–2008 | Cross-sectional | Cattle (3000) | 108 (3.6%) | Tissue | Slaughtered | PCR | 90 (3%) | [74] | ||
| 2013 * | Cross-sectional | Cattle (3474) | 78 (2.2%) | Slaughtered | ND | [75] | ||||
| 2013–2015 | Cross-sectional | Cattle (7064) | 242 (3.4%) | Tissue | Slaughtered | Culture; PCR | 31 (0.4%) | MIRU-VNTR; WGS | [76] | |
| 2020 * | Cross-sectional | Cattle (50) | 50 (100%) | Tissue | TST-positive | Culture; PCR | 45 (90%) | [77] | ||
| 2017 | Cross-sectional | Cattle (2710) | 444 (16.4%) | Blood and milk (444) | TST-positive | Culture; PCR | Blood: 44 (1.6%); Milk: 12 (0.004%) | [33] | ||
| Iran | 2003–2005 | Cross-sectional | Buffalo (140) | Tissue (140) | Slaughtered | Culture | 0 | RFLP | [45] | |
| 2003–2006 | Cross-sectional | Cattle (213) | Tissue (213) | Slaughtered | Culture; PCR | 56 (26.3%) | RFLP; MIRU-VNTR; Spoligotyping | |||
| 1996–2006 | Cross-sectional | Cattle (488); Buffalo (140) | Tissue | Slaughtered | Culture; PCR | Cattle: 67 (13.7%); Buffalo: 132 (28.1%) | RFLP; RD-PCR; MIRU-VNTR | [24,25] | ||
| 2016 * | Case report | Deer (1) | Tissue | Dead | PCR | 1 | IS6110 RFLP | [18] | ||
| 2016 | Cross-sectional | Cattle (1700) | Tissue | Healthy | PCR | 44 (8.5%) | [44] | |||
| Iraq | 2009 * | Cross-sectional | Cattle | Milk (68) | Culture; PCR | 7 (10.2%) | [47] | |||
| 2016 * | Cross-sectional | Cattle (300) | Tissue | Slaughtered | Culture | 4 (1.3%) | [46] | |||
| 2015–2016 | Cross-sectional | Cows (119) | 24 (20.2%) | Blood and milk | Live | 42 (35.2%) | [53] | |||
| 2019 | Cross-sectional | Cattle (106); Buffalo (90) | Cattle (12.2%); Buffalo (4.4%) | Live | ND | [34] | ||||
| 2010 | Cross-sectional | Cattle | Milk (102) | Healthy | Culture; PCR | 10 (9.8%) | [52] | |||
| 2016 | Cross-sectional | Cattle (186) | 32 (17.2%) | Live | ND | [78] | ||||
| 2014 * | Cross-sectional | Cattle (28) | 21 (75%) | Slaughtered | ND | [40] | ||||
| 2012 * | Cross-sectional | Cows (850) | 206 (24.2%) | Serum (260), Milk (45), swab nasal (45), tissue samples (98), from cattle | Live and slaughtered | Culture | 100 (11.8%) | [35] | ||
| 2016 * | Cross-sectional | Cattle (21) | 4 (19%) | Live | ND | [79] | ||||
| Morocco | 2014–2015 | Cross-sectional | Cattle (8658) | Tissue | Slaughtered | Culture; PCR | 144 (1.7%) | Spoligotyping | [48] | |
| 2018 * | Cross-sectional | Cattle (1087) | 222 (20.4%) | Live | ND | [80] | ||||
| 2000–2001 | Cross-sectional | Cattle (78) | Tissue | Slaughtered | Culture | 40 (51.3%) | [49] | |||
| 1990 | Cross-sectional | Cattle (246) | 114 (46.3%) | Blood and Tissue | Live and slaughtered | Culture | 73 (29.7%) | [81] | ||
| Sudan | 2007–2009 | Cross-sectional | Cattle (6680) | Tissue | Slaughtered | Culture; PCR | 12 (0.2%) | [50] | ||
| 2002 * | Cross-sectional | Cattle (120) | Lymph nodes and tissue | Slaughtered | Culture; PCR | 25 (20.8%) | IS6110 RFLP | [51] | ||
| Turkey | 2019 * | Case report | Cat (1) | Tissue | Slaughtered | Culture; PCR | 1 | [16] | ||
| 2008 | Cross-sectional | Cattle (145) | Milk (145) | Live | Culture; PCR | 1 (0.7%) | Spoligotyping | [82] | ||
| 2011–2012 | Cross-sectional | Cattle (5018) | Tissue (95) | Slaughtered | Culture | 32 (0.6%) | Spoligotyping; MIRU-VNTR | [83] | ||
| 2005 | Cross-sectional | Cattle (210) | 3 (1.4%) | Nasal (198); Milk (146) | Live | PCR | 3(1.42%) | [37] | ||
| 2017–2018 | Cross-sectional | Cattle (ND) | Lymph nodes and tissue | Slaughtered | Culture | 38 (ND) | EIRC-PCR; RAPD-PCR; OUT-PCR; Spoligotyping | [84] | ||
| Tunisia | 2005–2006 | Cross-sectional | Cattle (102) | Milk (306) | TST-positive | Culture; PCR | 5 (4.9%) | IS6110 RFLP; Spoligotyping; MIRU-VNTR | [85] | |
| 2014–2015 | Cross-sectional | Cattle (149) | Tissue (149) | Slaughtered | Culture | 96 (64.4%) | IS6110 RFLP; Spoligotyping; MIRU-VNTR | [86] | ||
| 2010–2011 | Cross-sectional | Cattle (100) | 48 (48%) | Tissue (100) | Slaughtered | Culture; PCR | 27 (27%) | Spoligotyping; MIRU-VNTR | [41] |
* Date of publication; † Based on interferon gamma release assay, ELISA, or tuberculin skin test (TST). If different methods were used, we adopted the results of the TST; ND, Not Determined; MIRU-VNTR, Mycobacterial Interspersed Repetitive Units—Variable Number of Tandem Repeats; MLVA, Multiple Locus Variable Number of Tandem Repeats Analysis; ETR, Exact Tandem Repeats; RFLP-PCR, Restriction Fragment Length Polymorphism-PCR; WGS: Whole Genome Sequencing. ¶ Prevalence = n of M. bovis infected cases/n of total population.
2. Mycobacterium bovis in Humans
In humans, Mycobacterium tuberculosis is the primary causative agent of tuberculosis, followed by other MTBC species, including M. bovis. Nationwide estimations in the MENA countries, when available, revealed a relatively low prevalence of M. bovis among tuberculosis patients in some countries (Table 2). The prevalence of M. tuberculosis and M. bovis in Turkey was 94.1% and 4.3%, respectively [87]. Similarly, a study showed that only one tuberculosis case was due to M. bovis out of 67 extrapulmonary [88] and 45 pulmonary [89] tuberculosis cases in Egypt. In Lebanon, a nationwide surveillance study on tuberculosis showed that 3.4% (12/348) of patients were infected with M. bovis, while the remaining cases had human-associated tuberculosis strains (i.e., M. tuberculosis or Mycobacterium africanum) [90]. In contrast, BTB appears to have rapidly increased in comparison to other forms in Tunisia in recent years. Specifically, the estimated prevalence increased from 2.2% in 2009 [91] to 92.4% in 2013 [92]. Additionally, when focusing on at-risk groups such as farmers or slaughterhouse employees, available data showed high proportions of zoonotic tuberculosis, ranging from 8% in Iraq [35] and 5.36% in Egypt [71], to 3.3% in Lebanon [93].
The paucity of data and deficiencies in rigorous monitoring along with inappropriate control measures might cause the disease to spread more within the MENA region and beyond. Several factors might promote the spread of BTB among humans in the MENA region. For example, inappropriate hand washing or disinfection following cow handling appears to be a major risk factor for M. bovis infections among dairy farm workers [42]. The consumption of contaminated raw or unpasteurized milk also plays a crucial role in the transmission of BTB and has been significantly associated with the elevated risk of M. bovis infections in dairy workers [20,42,94]. The latter might also affect other human and animal populations. For instance, in Turkey and Lebanon, raw milk is widely available, which increases the risk of becoming infected from contaminated milk [84]. Furthermore, close quarters and proximity to animals, inadequate ventilation, and cow crowding were significant contributors to an increase in the risk of BTB [42,68]. These conditions are relevant in rural regions and in refugee camps in several Middle Eastern countries (e.g., Lebanon, Jordan, Turkey) and some geographical locations (e.g., the Nile Delta and Valley in Egypt) [63,95,96,97].
Table 2. Burden of Mycobacterium bovis among humans in the MENA region.
| Country | Study Period | Study Design | Population (N) | Samples (N) for Active Tuberculosis Testing | Health Status | Identification Method | Prevalence ¶ of BTB (%) | Typing Method | References |
|---|---|---|---|---|---|---|---|---|---|
| Algeria | 2015–2018 | Cross-sectional | ND (98) | Sputum (98) | Pulmonary TB | 4 (4.3%) | WGS | [98] | |
| 2017–2019 | Cross-sectional | ND (1952) | Sputum (51), Bronchial aspiration fluids (7); Gastric aspirations (25); Extra-pulmonary specimens (32) |
TB patients | Culture; PCR | 7 (0.3%) | Spoligotyping; PhyloSNP |
[23] | |
| Egypt | 1998–2000 | Cross-sectional | ND (67) | Cerebrospinal fluid (67) | Meningitis patients | 1 (1.5%) | IS6110 RFLP; Spoligotyping |
[88] | |
| 2010–2011 | Cross-sectional | ND (42) | Sputum (42) | TB patients | Culture; PCR | 0 | [61] | ||
| 2013 | Cross-sectional | Dairy workers | Hand swab (50) | Healthy | Culture; PCR | 0 | [62] | ||
| 2007 * | Cross-sectional | ND (45) | Sputum (45) | Pulmonary TB | PCR | 1 (2.2%) | IS6110 RFLP; Spoligotyping |
[89] | |
| 2009 * | Cross-sectional | Farm workers (15) | Sputum (15) | Healthy | Culture | [39] | |||
| 2015 * | Cross-sectional | Farm workers (25) | Sputum (25) | Healthy | Culture; PCR | 1 (4%) | [42] | ||
| 2018 * | Cross-sectional | Farm workers (10) | Blood (10) | Healthy | Culture; PCR | [38] | |||
| 2015–2017 | Longitudinal | Humans in contact with camels (48) | Sputum (48); Serum (48) | Healthy | Culture; PCR | 0 | [19] | ||
| 2018–2019 | Cross-sectional | Farm workers (149) | Sputum (149) | Healthy | Culture; PCR | 8 (5.3%) | [71] | ||
| 2016 * | Cross-sectional | ND (10) | Sputum (3) | Diagnosed human | Culture; PCR | 0 | [72] | ||
| 2020 * | Cross-sectional | ND | Sputum (10) | Tuberculin test positive | Culture; PCR | 90% | Sequencing (Mpb70 genes) | [77] | |
| Iran | 2009 | Cross-sectional | ND | Mycobacteriology bank in MRC (60) | Culture | 1 (1.7%) | MIRU-VNTR Spoligotyping |
[99] | |
| 2004–2005 | Cross-sectional | ND (165) | Positives isolates (156) | TB patients | 15 (9.7%) | IS6110-RFLP MIRU-VNTR ETR-VNTR |
[100] | ||
| 1995–2004 | Cross-sectional | ND (30) | Serum (30) | Patients with disseminated BCG disease | 17 (56.6%) | [101] | |||
| 2016 | Case report | ND (1) | Tissue | Brain tuberculoma | PCR | 1 | [102] | ||
| Iraq | 2016 * | Cross-sectional | ND (186) | Sputum (186) | Healthy | Culture | 2 (1.1%) | [46] | |
| 2012 * | Cross-sectional | Farm workers and veterinary doctors (25) | Sputum (25); Serum (25) | Healthy | Culture | 2 (8%) | [35] | ||
| Lebanon | 2004–2005 | Cross-sectional | Workers and veterinary doctors (60) | Sputum (60) | Pulmonary TB | Culture; PCR | 2 (3.3%) | Spoligotyping | [93] |
| 2015–2017 | Cross-sectional | ND (13) | Clinical samples (13) | Suspected TB patients | Culture | 2 (15.4%) | IS6110 insertion; Spoligotyping; MIRU-VNTR; WGS | [103] | |
| 2016–2017 | Cross-sectional | ND (1104) | Clinical samples (1104) | TB patients | Culture; PCR | 12 (1.1%) | Spoligotyping; MIRU-VNTR; Deeplex-TB | [90] | |
| Morocco | 2000–2001 | Cross-sectional | ND (200) | Sputum (200) | Suspected TB patients | Culture | 18 (17.8%) | [49] | |
| 2011 * | Case report | ND (1) | Gastric specimen | Patient with erythema nodosum | Culture | 1 | [104] | ||
| Palestine | 2005–2010 | Cross-sectional | ND (53) | Sputum (53); Smears (31) | TB patients | Culture | 2 (3.7%) | Spoligotyping MIRU-VNTR |
[105] |
| Djibouti | 1999 | Cross-sectional | ND (153) | Lymph nodes (196) | Patients with adenopathy | Culture | 1 (0.7%) | [106] | |
| 1997–2011 | Cross-sectional | ND (411) | Sputum (411) | Suspected TB patients | Culture | 1 (0.2%) | Spoligotyping; VNTR-MLVA; WGS | [107] | |
| Saudi-Arabia | 2002–2005 | Cross-sectional | ND (1505) | Clinical isolates (1505) | Healthy | Culture | 13 (0.9%) | Spoligotyping; MIRU-VNTR | [108] |
| 2014–2016 | Cross-sectional | ND (2092) | Extrapulmonary clinical isolates (1003); Pulmonary clinical isolates (1089) | TB patients | Culture | Extrapulmonary: 119 (11.8%); Pulmonary: 32 (2.9%) | MIRU-VNTR | [109] | |
| Sudan | 1998–1999 | Cross-sectional | ND (105) | Sputum (105) | TB patients | PCR | 1 (0.9%) | Spoligotyping | [110] |
| Turkey | 2007–2010 | Cross-sectional | ND (188) | Clinical samples (188) | TB patients | Culture; PCR | 8 (4.3%) | [87] | |
| 2011–2012 | Cross-sectional | ND (10) | Sputum (10) | TB patients | Culture | 5 (50%) | Spoligotyping; MIRU-VNTR | [83] | |
| 2015 * | Case report | ND (1) | Tissue sample | NEMO-deficient patient | Culture; PCR | 1 | GenoType MTBC; Spoligotyping | [111] | |
| 2007–2010 | Cross-sectional | ND (2436) | Clinical samples (188) | TB patients | PCR | 8 (0.3%) | GenoType MTBC | [87] | |
| 2016 | Case report | Slaughterhouse worker (1) | Clinical sample | Skin lesion | Culture | 1 | GenoType MTBC | [112] | |
| 1996 * | Case report | Slaughterhouse worker (1) | Clinical sample | Flexor Tenosynovitis | Culture | 1 | [113] | ||
| 2007 * | Cross-sectional | ND (60) | Sputum (60) | TB patients | PCR | 8 (13.3%) | [114] | ||
| 2004–2014 | Cross-sectional | ND (220) | Clinical samples (220) | TB patients | Culture | 3 (1.4%) | Genotyping MTBC | [115] | |
| 2009–2014 | Cross-sectional | ND (482) | Clinical samples (482) | Pulmonary and extrapulmonary TB patients | Culture | 13 (2.7%) | Spoligotyping | [94] | |
| Tunisia | 2014–2018 | Case report | ND (4) | Tissue (4) | Spondylodiscitis patients | Culture; PCR | 4 | [116] | |
| 2009–2013 | Cross-sectional | ND (181) | Tissues (181) | Patients with adenopathy | Culture | 4 (2.2%) | [91] | ||
| 2013 | Cross-sectional | ND (174) | Lymph node (174) | Patients with adenopathy | Culture; PCR | 60 (34.4%) | [117] | ||
| 2013–2015 | Cross-sectional | ND (170) | Lymph nodes biopsy (144); Pus and abscess (10); Cerebrospinal fluid (8); Pleural fluid (1); Tissue (5); Bone scarping (2) | TB patients | Culture; PCR | 157 (92.4%) | [92] |
* Date of publication; If both were used, we adopted the results of the interferon gamma release assay; ND, Not Determined; MIRU-VNTR, Mycobacterial Interspersed Repetitive Units—Variable Number of Tandem Repeats; MLVA, Multiple Locus Variable Number of Tandem Repeats Analysis; ETR, Exact Tandem Repeats; RFLP-PCR, Restriction Fragment Length Polymorphism-PCR; WGS: Whole Genome Sequencing. ¶ Prevalence = n of M. bovis infected cases/n of total population.
3. Laboratory Methods for the Diagnosis and Typing of Mycobacterium bovis Adopted in the MENA Region
Although the reported detection methods in the studies from the MENA countries varied, active tuberculosis infections are still confirmed by mycobacterial culture which is considered the main approach, even for BTB. However, the adoption of molecular assays might be advantageous. For example, comparing molecular assays with microbiological culture revealed that the detection level of PCR-based assays was slightly greater than the conventional culture approach [118]. Moreover, molecular methods provide faster detection and identify the isolates at the species level. To confirm the identification of M. bovis, the detection of polymorphism in pncA or oxyR genes represents a valuable approach [119,120]. Recently, two PCR-based methods, VetMAXTM and GeneXpert®, were developed for M. bovis identification [1,121].
Traditionally, the molecular epidemiology of M. bovis is studied by DNA fingerprinting methods such as IS6110 RFLP (Restriction Fragment Length Polymorphism) [122]. Despite the method’s potential to identify outbreaks in hospitals and communities, its low discriminatory power for strains with low number of IS6110 copies imposes the need for other complementary tools, such as spoligotyping and Mycobacterial Interspersed Repetitive Units/Variable Number Tandem Repeat (MIRU/VNTR) [123,124]. Furthermore, next-generation genome sequencing is receiving significant attention for M. bovis diagnosis because it provides a higher discriminatory power, facilitating the investigation of MTBC molecular epidemiology and genetic diversity with greater resolution [125]. However, when sequencing is unavailable (due to limited resources in LMICs), the combination of MIRU-VNTR with spoligotyping is more suitable for tracking infections and detecting risk factors than either technique alone [99]. Regardless, the application of molecular techniques in the genotyping of M. bovis facilitates infection control and tracking processes. An obvious example of the latter is revealing the effect of the animal movement on the appearance of M. bovis in African countries, which was mainly due to cattle delivered from Europe. This cross-border link was detected by using the spoligotyping approach, with SB0120 and SB0121 spoligotypes being the most abundant of M. bovis [109]. Spoligotype SB0120 is the most common circulating type worldwide while SB0121 mainly exists in Europe [126]. This geographical spillover was also observed in the MENA countries, especially Tunisia, Algeria, Morocco [34,98,116] and Iran [24].
4. Antimicrobial Resistance among Mycobacterium bovis Isolates in the MENA Region
A major factor that might complicate the control of M. bovis in the MENA region is the drug resistant properties of this zoonotic agent. M. bovis has a natural resistance to pyrazinamide, an essential drug for standard short-course anti-tuberculosis therapy in humans. Unfortunately, phenotypic susceptibility to pyrazinamide is often not tested in the MENA region. Since the currently adopted diagnostic tools do not usually differentiate M. bovis from other MTBC species in MENA countries, BTB patients receive inadequate treatment, risking poorer outcomes and enhancing the selection of drug-resistant strains. Additionally, alarming data on drug resistance have been reported recently in the MENA region. Antimicrobial resistance genes were found in isolates retrieved from both infected humans and animals [95,127,128]. M. bovis strains were most commonly resistant to rifampicin and isoniazid in several reports from the MENA region [71,110,111]. A rifampicin (RIF)-resistant M. bovis strain was first reported in a Turkish patient in 2015, an 8-month-old male infant with nuclear factor-kB essential modulator (NEMO) deficiency [111]. Moreover, an Egyptian study reported the spread of multidrug-resistant M. bovis strains among buffaloes [68]. In Sudan, 4% of M. bovis isolates possessed resistance to both rifampicin and isoniazid due to genetic mutations [110], while, in Palestine, mutated rpoB and katG genes were identified in clinical samples from three unrelated individuals who did not respond to the first line of antituberculosis drug therapy [105].
This entry is adapted from the peer-reviewed paper 10.3390/diseases11010039
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