Zoonotic Tuberculosis - The Changing Landscape.

Despite slow reductions in the annual burden of active human tuberculosis (TB) cases, zoonotic TB (zTB) remains a poorly monitored and an important unaddressed global problem. There is a higher incidence in some regions and countries, especially where close association exists between growing numbers of cattle (the major source of Mycobacterium bovis) and people, many suffering from poverty, and where dairy products are consumed unpasteurised. More attention needs to be focused on possible increased zTB incidence resulting from growth in dairy production globally and increased demand in low income countries in particular. Evidence of new zoonotic mycobacterial strains in South Asia and Africa (e.g. M. orygis), warrants urgent assessment of prevalence, potential drivers and risk in order to develop appropriate interventions. Control of M. bovis infection in cattle through detect and cull policies remain the mainstay of reducing zTB risk, whilst in certain circumstances animal vaccination is proving beneficial. New point of care diagnostics will help to detect animal infections and human cases. Given the high burden of human tuberculosis (caused by M. tuberculosis) in endemic areas, animals are affected by reverse zoonosis, including multi-drug resistant strains. This, may create drug resistant reservoirs of infection in animals. Like COVID-19, zTB is evolving in an ever-changing global landscape.

Interactions between helminths and tuberculosis infections: Implications for tuberculosis diagnosis and vaccination in Africa.

Africa is the second most populous continent and has perennial health challenges. Of the estimated 181 million school aged children in sub-Saharan Africa (SSA), nearly half suffer from ascariasis, trichuriasis, or a combination of these infections. Coupled with these is the problem of tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection, which is a leading cause of death in the region. Compared to the effect of the human immunodeficiency virus on the development of TB, the effect of chronic helminth infections is a neglected area of research, yet helminth infections are as ubiquitous as they are varied and may potentially have profound effects upon host immunity, particularly as it relates to TB infection, diagnosis, and vaccination. Protection against active TB is known to require a clearly delineated T-helper type 1 (Th1) response, while helminths induce a strong opposing Th2 and immune-regulatory host response. This Review highlights the potential challenges of helminth-TB co-infection in Africa and the need for further research.

Genetic diversity of Mycobacterium tuberculosis complex strains isolated from livestock workers and cattle in Nigeria.

Molecular typing techniques are useful in understanding tuberculosis epidemiology; yet, they have been under-utilised at the human-animal interface in Nigeria. Sixty-four Mycobacterium tuberculosis complex (MTBC) isolates including 42 M. tuberculosis, 13 M. bovis and nine M. africanum obtained from livestock workers (LW, n = 47) and their cattle (n = 17) in three geographical zones of Nigeria were genotyped to identify and evaluate the genetic diversity of the circulating MTBC using spoligotyping. Distribution into clades of M. tuberculosis revealed; 45.3% Uganda I- [SIT46- cattle: 1; LW: 28], 14.1% Latin American Mediterranean- [SIT61, cattle: 1; LW: 8], and 1.6% T- [SIT53-LW: 1]. The M. bovis strains were 6.3% SB0944 [cattle: 4] and 1.6% each of SB0300, SB1026, SB1027 and SB1439 [cattle: 4]. Seventeen MTBC isolates [cattle: 7; LW: 10] yielded 14 new spoligotype patterns including three M. tuberculosis strains (three isolates), five M. bovis strains (five isolates) and six M. africanum strains (nine isolates), two of which belonged to MAF1. Only few families namely, the not previously described Uganda I-, LAM and SB0944 are predominant among the LW and cattle, with other types in lower prevalences. The strain population structure indicates an intriguing diversity and possible zoonotic linkage with consequences for TB control in the country. The need to employ newer molecular techniques such as Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeats and whole genome sequence to decipher circulating MTBC strains in Nigeria is advocated.

The problem of resistance in Mycobacterium tuberculosis may be underestimated in Africa.

Background: The true burden of tuberculosis (TB) and particularly multidrug-resistant (MDR) TB in Sub-Saharan Africa has remained underestimated. Methods: We investigated drug susceptibility profile and genetic diversity of Mycobacterium tuberculosis isolates collected from confirmed tuberculosis patients in Ibadan, southwestern Nigeria. Results: We confirmed that from 74 randomly selected Mycobacterium tuberculosis isolates available for drug susceptibility testing in Ibadan, in 2011, 13.5% of them were MDR-TB. Conclusions: This figure is obviously above the national and World Health Organization figures.

Prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria.

Using a cross-sectional survey, we determined the prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria. Antibodies to Brucella species in serum samples were tested using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (cELISA); for milk, the milk ring test (MRT) and indirect-ELISA (i-ELISA) were used. Questionnaire was administered to cattle herdsmen to determine factors predisposing the animals to bovine brucellosis. Data were analyzed using STATA 12. From 513 serum and 635 milk samples tested among 120 herds, overall animal-level prevalence of 10.1% (95% CI 7.5-12.7%) and 20.2% (95% CI 17.1-23.3%) were recorded by RBT and MRT, respectively; while 9.4% (95% CI 6.9-11.9%) and 17.8% (95% CI 14.8-20.8%) were obtained using cELISA and i-ELISA, respectively. In all, from the 120 herds tested, 29.2% and 43.3% were positive by RBT and MRT, respectively. Multivariable logistic regression revealed that herd location (OR = 8.12, 95% CI 1.68-38.90) and improper disposal of placenta/fetus (OR = 17.33, 95% CI 4.81-62.33) were predictors for a seropositive herd using RBT; while herd location (OR = 5.13, 95% CI 1.27-20.28), large herd size (OR = 2.62, 95% CI 1.15-5.85), and occurrence of abortion for a year or more (OR = 4.62, 95% CI 1.53-13.71) were predictors of seropositivity to antibodies to Brucella spp. using MRT. We found high prevalence of brucellosis in cattle herds under extensive management system in southwestern Nigeria. Urgent and coordinated control strategies are required to mitigate this problem.

Prevalence and risk factors of mycobacterial infections in farm and trade cattle in southwestern Nigeria.

We evaluated the prevalence of mycobacterial infections (i.e., Mycobacterium bovis and non-tuberculous mycobacteria [NTM]) and their associated risk factors among cattle herds and trade cattle in southwestern Nigeria. Through cross-sectional study design, cattle herds from three locations were screened using the single intradermal comparative cervical tuberculin test based on two diagnostic standards; more than 4 mm (˃ 4 mm) and more than 2 mm (˃ 2 mm) cut-off points. Abattoir study involved screening trade cattle for tuberculous lesions. Overall, 515 cattle from 45 herds were screened. Using > 4 mm, animal level and herd prevalence of 11.7 and 46.7% were recorded, respectively. Applying the ˃ 2 mm cut-off, animal level and herd prevalence increased to 31.1 and 60.0%, respectively. Significantly, using the ˃ 2 mm cut-off, cattle in medium size herds/extensive management system (OR = 1.6; 95% CI 1.1-2.5) and Sokoto Gudali (OR = 2.3; 95% CI 1.4-3.8) were more at risk of being positive reactors, while Rahaji (OR = 0.3; 95% CI 0.1-0.7) breeds of cattle and cows in the peri-urban area (OR = 0.4; 95% CI 0.2-0.9) were less at risk of being positive reactors. Again, M. avium reactor of 21.7% was observed. In the abattoir, 1797 cattle were examined with 126 lesions suggestive of tuberculosis (TB). Culture/molecular analyses confirmed 2.2% M. bovis and 0.9% NTM infections. Risk factors associated with bovine TB among trade cattle were sex (OR = 4.0; 95% CI 1.2-13.5) and age (OR = 0.3; 95% CI 0.1-0.9). We confirm 11.7% prevalence of mycobacterial infections among populations of cattle screened with breed and herd size being major risk factors.

Sero-epidemiological survey and risk factors associated with bovine brucellosis among slaughtered cattle in Nigeria.

Bovine brucellosis is endemic in Nigeria; however, limited data exist on nationwide studies and risk factors associated with the disease. Using a cross-sectional sero-epidemiological survey, we determined the prevalence of and risk factors for brucellosis in slaughtered cattle in three geographical regions of Nigeria. Serum samples from randomly selected unvaccinated cattle slaughtered over a period of 3 years (between December 2010 and September 2013) from northern, southern and south-western Nigeria were tested for antibodies to Brucella abortus using the Rose Bengal test. Data associated with risk factors of brucellosis were analysed by Stata Version 12. In all, 8105 cattle were screened. An overall seroprevalence of 3.9% (315/8105) was recorded by the Rose Bengal test, with 3.8%, 3.4% and 4.0% from the northern, southern and south-western regions, respectively. Bivariate analysis showed that cattle screened in northern Nigeria were less likely to be seropositive for antibodies to Brucella spp. than those from south-western Nigeria (odds ratio = 0.94; 95% confidence interval: 0.73-1.22). However, logistic regression analysis revealed that breed ( p = 0.04) and sex ( p £ 0.0001) of cattle were statistically significant for seropositivity to Brucella spp. The study found that brucellosis was endemic at a low prevalence among slaughtered cattle in Nigeria, with sex and breed of cattle being significant risk factors. Considering the public health implications of brucellosis, we advocate coordinated surveillance for the disease among diverse cattle populations in Nigeria, as is carried out in most developed countries.

Serological investigation of bovine brucellosis in three cattle production systems in Yewa Division, south-western Nigeria.

Limited data are available on the risk factors responsible for the occurrence of brucellosis amongst different cattle production systems in Nigeria despite its significant impact on livestock production. Consequently, a cross-sectional study was conducted to determine the prevalence of bovine brucellosis in three cattle production systems in Yewa Division of Ogun State, south-western Nigeria. A total of 279 blood samples (sedentary = 88; transhumance = 64; trade = 127) were examined for antibodies to Brucella sp. using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (cELISA). Overall, 24 (8.6%) and 16 (5.7%) of the animals tested seropositive for Brucella using RBT and cELISA, respectively. The herd seroprevalences based on RBT and cELISA were 31.6% and 15.8%, respectively. The results using cELISA reveal higher seroprevalence in the trade cattle (7.9%; confidence intervals [CI] = 3.2% - 12.6%) and those in a sedentary system (5.7%; CI = 0.9% - 10.5%) than in cattle kept under a transhumant management system (1.6%; CI = 1.5% - 4.7%). Age (> 3 years; p = 0.043) and breed (Djali; p = 0.038) were statistically significant for seropositivity to brucellosis based on cELISA, but sex (female, p = 0.234), production system (trade and sedentary; p = 0.208) or herd size (> 120; p = 0.359) was not. Since breeding stock is mostly sourced from trade and sedentary cattle, it is important that routine serological screening should be conducted before introducing any animal into an existing herd.

Knowledge and practices related to bovine brucellosis transmission amongst livestock workers in Yewa, south-western Nigeria.

Brucellosis is an endemic disease in the animal population in Nigeria and of major public health importance, particularly amongst livestock workers who are ignorant of the risk of Brucella infection. Therefore, to gain insight into the knowledge and practices related to brucellosis transmission amongst livestock holders (LH) and livestock marketers (LM) in Yewa, an international livestock trading centre in south-western Nigeria, we conducted an interviewbased study using a cluster sampling technique. In all, a total of 157 respondents comprising 54 LH and 103 LM were interviewed. Two-thirds (69.5%) of the two groups had poor knowledge of brucellosis with no significant difference between them (p = 0.262). Furthermore, consumption of unpasteurised milk, uncooked meat and its products, co-habitation with animals, and poor hygiene were significant risk practices identified as possible means of transfer of Brucella infection from animals to humans amongst these livestock workers (p < 0.05). In conclusion, our findings revealed that poor knowledge and practices related to the consumption of unpasteurised or unboiled dairy products, contaminated beef, and unhygienic practices are factors that will facilitate Brucella infections amongst livestock workers in Nigeria. Therefore, there is a need for more public health enlightenment programmes, as well as implementation of brucellosis control measures in the cattle populations.

Exposure of dentists to Mycobacterium tuberculosis, Ibadan, Nigeria.

To determine the prevalence of Mycobacterium tuberculosis infection among dental patients and to assess dentists' risk for exposure, we conducted a study among dental patients at a large tertiary hospital in Nigeria, a country where tuberculosis is endemic. Ten (13%) of 78 sputum samples obtained were positive for M. tuberculosis.

Prevalence of bovine tuberculosis in Jigawa State, northwestern Nigeria.

We determined the prevalence of bovine tuberculosis in Jigawa State, northwestern Nigeria using the comparative intradermal tuberculin test in 22 herds consisting of 922 cattle with overall and individual prevalence of 1.08% (10/922) and 45.45% (10/22) obtained, respectively.

Mycobacterium bovis, but also M. africanum present in raw milk of pastoral cattle in north-central Nigeria.

Using deletion typing technique, five mycobacteria isolated from unpasteurised milk samples from cows in north-central Nigeria were characterized as Mycobacterium bovis (n = 4) and M. africanum (n = 1). This report emphasizes that transmission between the animal and human reservoir is a serious threat in Nigeria.

Bovine fetal wastage in Southwestern Nigeria: a survey of some abattoirs.

As a result of inadequate veterinary services and indiscriminate slaughter of animals in most Nigerian abattoirs, pregnant animals are often slaughtered resulting in wastage of scarce protein made available to the people. To this end, an evaluation of the volume of pregnant cows slaughtered at some abattoirs in Southwestern Nigeria between 2005 and 2007 based on meat inspection records was carried out with a view to determining the level of fetal wastage in this part of the country. A total of 321,448 cows were slaughtered, out of which, 16,092 (5.01%) were pregnant. The fetal wastages across the four seasons of the study period were statistically significant (P < 0.05); the late dry season showing the highest percentage. There was a downward trend across the years, and this was considerably lower in 2007 than the other 2 years which were not statistically different from each other (X (A2005) = 224.33; X (A2006) = 216.38; X (B2007) = 126.38). Our results indicated a considerable level of slaughtering of pregnant cows in the abattoirs studied. Hence, we advocate stepping up routine veterinary checks and interventions among trade animals in order to salvage the high level of fetal wastage in the region and the country at large.

Co-infection of brucellosis and tuberculosis in slaughtered cattle in Ibadan, Nigeria: a case report.

The authors present a case report on co-infection of brucellosis and tuberculosis in cattle slaughtered at the Bodija abattoir in Ibadan, Nigeria. Out of 32 animals that were seropositive for brucellosis using the Rose Bengal test, indirect enzyme-linked immunosorbent assay (ELISA) and competitive ELISA, six were also demonstrated as being infected with tuberculosis through mycobacterial culture. This is the first report of co-infection of brucellosis and tuberculosis in cattle slaughtered in Nigeria. There is a need for further studies to investigate this occurrence.