Intrafamilial cluster of pulmonary tuberculosis due to Mycobacterium bovis of the African 1 clonal complex

Assessment of the knowledge, attitudes, and practices toward human tuberculosis amongst rural communities in Chad

Introduction

Tuberculosis (TB) is an infectious zoonotic disease caused by bacteria belonging to the Mycobacterium tuberculosis complex. In sub-Saharan African countries such as Chad, TB is endemic and causes a high burden on humans and animals through morbidity, mortality, and reduced productivity in livestock. To effectively prevent and control the disease, strong coordination between policymakers, health and veterinary services, civil society organizations, and communities is needed. It also requires an understanding of the knowledge the communities have regarding TB. However, such knowledge is under-investigated, especially in rural areas. How knowledge affects people's attitudes and practices is also unclear. The main objective of this study was to investigate the knowledge, attitudes, and practices (KAP) of Chadian rural communities to better involve them in TB surveillance programs.

Methods

A survey was conducted in 2021 in five rural health centers. Face-to-face interviews were conducted with persons suspected of having TB, and data on KAP were recorded and analyzed.

Results

In total, 139 participants were enrolled. Overall, the knowledge and attitude of the participants were found to be good to moderate, with 126 (90.6%) and 97 (69.7%) having good knowledge and attitude, respectively. However, their practices were found to be rather weak, with only 40 (28.7%) participants having good practices. Men were found to have good knowledge about the disease significantly more often than women. Poor attitude was significantly associated with a mobile lifestyle compared to settled lifestyles and with farmers (mainly engaged in agriculture) compared to breeders (livestock keepers). Poor health practices were associated more with men than women and with settled lifestyles compared to a mobile lifestyle. Good practices were found to be in line with good knowledge and good attitudes; however, in the analyses, the association was not significant [OR knowledge = 5.83 (95% C.I. 0.6842.83), p = 0.112; OR attitude = 2.09 (95% C.I. 0.875.04), p = 0.100]. Furthermore, attitude was not associated with knowledge [OR = 1.03 (95% C.I. 0.303.55), p = 0.964].

Discussion and conclusion

Our study highlights the need for targeted sensitization and awareness campaigns for communities with poor knowledge and attitudes regarding TB. These campaigns should also include practical training to increase the level of good practice rather than simply providing knowledge.

Genetic Diversity and Population Structure of Mycobacterium bovis at the Human-Animal-Ecosystem Interface in France: “A One Health Approach”

Mycobacterium bovis infects cattle and wildlife, and also causes a small proportion of tuberculosis cases in humans. In most European countries, M. bovis infections in cattle have been drastically reduced, but not eradicated. Here, to determine the M. bovis circulation within and between the human, cattle, and wildlife compartments, we characterized by spoligotyping and mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing the genetic diversity of M. bovis isolates collected from humans, cattle, and wildlife in France from 2000 to 2010. We also assessed their genetic structure within and among the different host groups, and across time and space. The M. bovis genetic structure and its spatiotemporal variations showed different dynamics in the human and animal compartments. Most genotypes detected in human isolates were absent in cattle and wildlife isolates, possibly because in patients, M. bovis infection was contracted abroad or was the reactivation of an old lesion. Therefore, they did not match the genetic pool present in France during the study period. However, some human-cattle exchanges occurred because some genotypes were common to both compartments. This study provides new elements for understanding M. bovis epidemiology in France, and calls for increased efforts to control this pathogen worldwide.

Zoonotic Tuberculosis in Humans: Control, Surveillance, and the One Health Approach

Zoonotic tuberculosis is a reemerging infectious disease in high-income countries and a neglected one in low- and middle-income countries. Despite major advances in its control as a result of milk pasteurization, its global burden is unknown, especially due the lack of surveillance data. Additionally, very little is known about control strategies. The purpose of this review was to contextualize the current knowledge about the epidemiology of zoonotic tuberculosis and to describe the available evidence regarding surveillance and control strategies in high-, middle-, and low-income countries. We conducted this review enriched by a One Health perspective, encompassing its inherent multifaceted characteristics. We found that the burden of zoonotic tuberculosis is likely to be underreported worldwide, with higher incidence in low-income countries, where the surveillance systems are even more fragile. Together with the lack of specific political commitment, surveillance data is affected by lack of a case definition and limitations of diagnostic methods. Control measures were dependent on risk factors and varied greatly between countries. This review supports the claim that a One Health approach is the most valuable concept to build capable surveillance systems, resulting in effective control measures. The disease characteristics and suggestions to implement surveillance and control programs are discussed.

Mycobacterium bovis in Burkina Faso: epidemiologic and genetic links between human and cattle isolates

BACKGROUND

In sub-Saharan Africa, bovine tuberculosis (bTB) is a potential hazard for animals and humans health. The goal of this study was to improve our understanding of bTB epidemiology in Burkina Faso and especially Mycobacterium bovis transmission within and between the bovine and human populations.

METHODOLOGY/PRINCIPAL FINDINGS

Twenty six M. bovis strains were isolated from 101 cattle carcasses with suspected bTB lesions during routine meat inspections at the Bobo Dioulasso and Ouagadougou slaughterhouses. In addition, 7 M. bovis strains were isolated from 576 patients with pulmonary tuberculosis. Spoligotyping, RDAf1 deletion and MIRU-VNTR typing were used for strains genotyping. The isolation of M. bovis strains was confirmed by spoligotyping and 12 spoligotype signatures were detected. Together, the spoligotyping and MIRU-VNTR data allowed grouping the 33 M. bovis isolates in seven clusters including isolates exclusively from cattle (5) or humans (1) or from both (1). Moreover, these data (genetic analyses and phenetic tree) showed that the M. bovis isolates belonged to the African 1 (Af1) clonal complex (81.8%) and the putative African 5 (Af5) clonal complex (18.2%), in agreement with the results of RDAf1 deletion typing.

CONCLUSIONS/SIGNIFICANCE

This is the first detailed molecular characterization of M. bovis strains from humans and cattle in Burkina Faso. The distribution of the two Af1 and putative Af5 clonal complexes is comparable to what has been reported in neighbouring countries. Furthermore, the strain genetic profiles suggest that M. bovis circulates across the borders and that the Burkina Faso strains originate from different countries, but have a country-specific evolution. The genetic characterization suggests that, currently, M. bovis transmission occurs mainly between cattle, occasionally between cattle and humans and potentially between humans. This study emphasizes the bTB risk in cattle but also in humans and the difficulty to set up proper disease control strategies in Burkina Faso.

Current knowledge and pending challenges in zoonosis caused by Mycobacterium bovis: a review

Mycobacterium bovis is both the causative agent of bovine tuberculosis (TB) and a zoonotic pathogen. In humans, considerably fewer cases of TB are caused by M. bovis than M. tuberculosis; nevertheless, diagnostic limitations mean that currently available data on prevalence grossly underestimate the true dimension of the problem. The routes of transmission from animals to humans are well known and include direct exposure to infected animals or consumption of contaminated animal products. Application of fingerprinting tools facilitates analysis of the molecular epidemiology of M. bovis in animal-to-human and human-to-human transmission. Apart from cattle and M. bovis, other animal species and members within the M. tuberculosis complex can contribute to the zoonosis. Improvements in diagnostic techniques, application of more advanced discriminatory genotyping tools, and collaboration between veterinary and human health care researchers are key to our understanding of this zoonosis.

Low prevalence of bovine tuberculosis in Somali pastoral livestock, southeast Ethiopia

A cross-sectional study of bovine tuberculosis (BTB) detected by the comparative intradermal tuberculin test (CIDT) was conducted in livestock of the Somali region in southeast Ethiopia--in four pastoral associations from January to August 2009. In 94 herds, each of 15 cattle, camels, and goats was tested per herd leading to a total of 1,418 CIDT tested animals, with 421 cattle, 479 camels, and 518 goats. A herd was considered positive if it had at least one reactor. Prevalence per animal species was calculated using a xtgee model for each species. The individual animal prevalence was 2.0% [95% confidence interval (CI), 0.5-8.4], 0.4% (95% CI, 0.1-3%), and 0.2% (95% CI, 0.03-1.3) in cattle, camels, and goats, respectively. Prevalence of avian mycobacterium purified protein derivative (PPD) reactors in cattle, camels, and goats was 0.7% (95% CI, 0.2-2.0%), 10.0% (95% CI, 7.0-14.0%), and 1.9 (95% CI, 0.9-4.0%), respectively, whereby camels had an odds ratio of 16.5 (95% CI, 5.0-55.0) when compared to cattle. There was no significant difference between livestock species in BTB positivity. In the present study, the prevalence of bovine tuberculosis was low in Somali pastoral livestock in general and in camels and goats in particular. The high proportion of camel reactors to avian PPD needs further investigation of its impact on camel production.

Zoonotic transmission of tuberculosis between pastoralists and their livestock in South-East Ethiopia

Despite huge global efforts in tuberculosis (TB) control, pastoral areas remain under-investigated. During two years sputum and fine needle aspirate (FNA) specimens were collected from 260 Ethiopian pastoralists of Oromia and Somali Regional States with suspected pulmonary TB and from 32 cases with suspected TB lymphadenitis. In parallel, 207 suspected tuberculous lesions were collected from cattle, camels and goats at abattoirs. All specimens were processed and cultured for mycobacteria; samples with acid-fast stained bacilli (AFB) were further characterized by molecular methods including genus and deletion typing as well as spoligotyping. Non-tuberculous mycobacteria (NTM) were sequenced at the 16S rDNA locus. Culturing of AFB from human sputum and FNA samples gave a yield of 174 (67%) and 9 (28%) isolates, respectively. Molecular typing was performed on 173 of these isolates and 160 were confirmed as Mycobacterium tuberculosis, three as M. bovis, and the remaining 10 were typed as NTMs. Similarly, 48 AFB isolates (23%) yielded from tuberculous lesions of livestock, of which 39 were molecular typed, including 24 M. bovis and 4 NTMs from cattle, 1 M. tuberculosis and 1 NTM from camels and 9 NTMs from goats. Isolation of M. bovis from humans and M. tuberculosis from livestock suggests transmission between livestock and humans in the pastoral areas of South-East Ethiopia.

The global distribution and phylogeography of Mycobacterium bovis clonal complexes

The consequences of the clonality of the Mycobacterium tuberculosis complex are described and, in particular, the identification of clonal complexes. Clonal complexes are groups of strains all descended from a single cell that was the most recent common ancestor (MRCA) of the clonal complex and all bearing characteristics derived from the MRCA. Three clonal complexes of Mycobacterium bovis have been identified and called African 1, African 2 and European 1. Members of each clonal complex have a distinct spoligotype signature and are identified by a unique deletion present in each member of the clonal complex. The African 1 and African 2 clonal complexes are geographically localised to Central-West Africa and East Africa, respectively and have not been found in cattle outside of these regions. However, the European 1 clonal complex is globally distributed and has been identified in the British Isles, former British colonies, The Americas as well as Kazakhstan and Korea. It is suggested that modern cattle breeds, such as Herefords, bred in the UK in the 18th Century, would provide a good vehicle for the global distribution of this closely related group of strains. The phylogeography of M. bovis and M. tuberculosis are compared and in particular the diversity of M. tuberculosis in Africa, compared with the localised dominance of M. bovis clonal complexes, is highlighted. Finally, the practical use of M. bovis clonal complexes is reviewed, however, a more significant use of M. bovis clonal complexes is to generate testable hypotheses to understand the pathogenicity and spread of this important veterinary pathogen. This first look at the phylogeography of M. bovis clonal complexes has shown surprising geographical localisation of molecular types but also hints strongly that much of the worldwide distribution of bovine pathogen resulted from human trade in cattle within the last 200 years.

Perspectives on the History of Bovine TB and the Role of Tuberculin in Bovine TB Eradication

Tuberculosis remains a significant disease of animals and humans worldwide. Bovine tuberculosis is caused by Mycobacteria with an extremely wide host range and serious, although currently probably underdiagnosed, zoonotic potential. Where bovine tuberculosis controls are effective, human zoonotic TB, due to Mycobacterium bovis or M. caprae, is uncommon and clinical cases are infrequent in cattle. Therefore, the control and ultimate eradication of bovine tuberculosis is desirable. Tuberculin tests are the primary screening tool used in bovine eradication. The choice of tuberculin test is dependent on the environment in which it is to be used. Tuberculin potency is critical to test performance, and the accurate determination of potency is therefore particularly important. The design of a control or eradication programme should take into consideration the fundamental scientific knowledge, the epidemiological profile of disease, the experience of other eradication programmes, and the presence, in the same ecosystem, of maintenance hosts, in which infection is self-sustaining and which are capable of transmitting infection. A control or eradication programme will necessarily require modification as it progresses and must be under constant review to identify the optimal desirable goals, the efficacy of policy, and constraints to progress.