Prevalence and risk factors for infection of bovine tuberculosis in indigenous cattle in the Serengeti ecosystem, Tanzania

Seroprevalence and risk factors associated with bovine tuberculosis in cattle in Eastern Bhutan

Bovine tuberculosis (bTB) is a chronic zoonotic disease affecting cattle of all age groups including wild animals. It poses a significant threat to public health and high economic losses to dairy farmers. While the disease has been eradicated from most of the developed countries through extensive surveillance, testing and culling strategy, it is endemic in Africa, Asia, and the Middle East countries. Currently, there is limited research regarding the prevalence of bTB in cattle in Bhutan. This study aimed to determine the seroprevalence of bTB in cattle in six districts of eastern Bhutan. A two-stage probability proportional to size (PPS) sampling strategy was used to determine the number of animals from which serum samples needed to be collected in each district and sub-district. All farms and cattle for sampling were randomly selected from the data in the annual livestock census of 2020. The samples were tested using bTB ELISA test kit. The seroprevalence and their 95% confidence intervals were calculated. Logistic regression models were constructed to assess the influence of various individual animal and environmental risk factors (breed, age, sex, source of animal, body condition scores of animals, respiratory system status) associated with sero-positivity in animals. The study revealed an apparent seroprevalence of 2.57% (25/971 cattle; 95% CI:1.58-3.57), with an estimated true seroprevalence of 0.91% (95% CI: 0.0-2.81). However, none of the variables were found to be significantly associated with bTB seroprevalence in cattle. We recommend, further sampling and employment of confirmatory testing to fully ascertain the extent of bTB in the cattle herds in eastern Bhutan for prevention and control.

Prevalence and risk factors of bovine tuberculosis in cattle in selected districts of Fafan pastoral settings, Eastern Ethiopia

Cross-sectional study was conducted from October 2021 to August 2022 to investigate the prevalence and associated risk factors of bovine tuberculosis in cattle in selected districts of the pastoral settings of Fafan zone, Somali region, eastern Ethiopia. A comparative intradermal tuberculin test was performed using purified protein derivatives. Animal-related characteristics, and the owner's knowledge on the importance of BTB were collected using a structured questionnaire. The prevalence was 11.24 % (95 % CI, 8.61-14.35) and 43.3 % (95 % CI, 33.27-53.75) at the individual and herd levels, respectively. There were statistically significant differences in the proportions of positive reactor animals according to body condition score (P = 0.000), age (P = 0.048), seasonal migration (P = 0.038), parity number (P = 0.005), and reproductive status (P = 0.037). Animals with poor body condition scores had a significantly higher likelihood of testing positive, with their odds being 11.4 times greater (COR = 11.408, CI = 3.43-37.94, P < 0.001). In multivariate logistic regression, poor body condition score remained significantly associated with the odds of a positive reaction to tuberculosis (AOR = 0.137, CI = 0.053-0.356, P < 0.001). Similarly, the analysis showed that seasonal migration (AOR = 2.882, CI = 1.155-7.191, P = 0.023) and parity number (AOR = 11.64, CI = 1.818-74.464, P = 0.010) were significant predictors of bovine tuberculosis infection in cattle. According to the questionnaire, 14.2 % (17 of 120) and 13.3 % (16 of 120) of the respondents were knowledgeable about bovine tuberculosis and its transmission from animals to humans, and vice versa, respectively. The general judgment of herders' understanding of bovine tuberculosis transmission methods to humans was very low. The study findings showed a high prevalence of bovine tuberculosis in the study area, emphasizing the need for an effective control and prevention strategy.

Occurrence of tuberculosis among people exposed to cattle in Bangladesh

BACKGROUND

Tuberculosis (TB) has been an important public health concern in Bangladesh. The most common cause of human TB is Mycobacterium tuberculosis, while bovine TB is caused by Mycobacterium bovis.

OBJECTIVE

The objective of this study was to determine the frequency of TB in individuals with occupational exposure to cattle and to detect Mycobacterium bovis among cattle in slaughterhouses in Bangladesh.

METHODS

Between August and September 2015, an observational study was conducted in two government chest disease hospitals, one cattle market, and two slaughterhouses. Sputum samples were collected from individuals who met the criteria for suspected TB and had been exposed to cattle. Tissue samples were collected from cattle that had low body condition score(s). Both humans and cattle samples were screened for acid-fast bacilli (AFB) by Ziehl-Neelsen (Z-N) staining and cultured for Mycobacterium tuberculosis complex (MTC). Region of difference (RD) 9-based polymerase chain reaction (PCR) was also performed to identify Mycobacterium spp. We also conducted Spoligotyping to identify the specific strain of Mycobacterium spp.

RESULTS

Sputum was collected from a total of 412 humans. The median age of human participants was 35 (IQR: 25-50) years. Twenty-five (6%) human sputum specimens were positive for AFB, and 44 (11%) were positive for MTC by subsequent culture. All (N = 44) culture-positive isolates were confirmed as Mycobacterium tuberculosis by RD9 PCR. Besides, 10% of cattle workers were infected with Mycobacterium tuberculosis in the cattle market. Of all TB (caused by Mycobacterium tuberculosis) infected individuals, 6.8% of individuals were resistant to one or two anti-TB drugs. The majority of the sampled cattle (67%) were indigenous breeds. No Mycobacterium bovis was detected in cattle.

CONCLUSIONS

We did not detect any TB cases caused by Mycobacterium bovis in humans during the study. However, we detected TB cases caused by Mycobacterium tuberculosis in all humans, including cattle market workers.

The consequential costs of bovine tuberculosis (bTB) breakdowns in England and Wales

Bovine tuberculosis (bTB) is a globally distributed zoonotic disease with significant economic impacts. Control measures in Great Britain include testing for and culling diseased animals. Farmers receive compensation for the value of culled animals, but not for the consequential costs of having to comply with testing and associated control measures. Such uncompensated costs can be significant. We present results of a survey of 1,600 dairy and beef farm holdings conducted in England and Wales to update and improve estimates of these consequential costs.Estimated costs are positively skewed and show considerable variance, which is in agreement with previous, smaller scale surveys of bTB: most farms experiencing bTB incur modest costs but some suffer significant costs. Testing, movement restrictions and output losses account for over three quarters of total uncompensated costs. Total costs rise with herd size and duration of controls. The composition of consequential costs changes as total costs increase, with an increasing proportion of the costs being associated with output losses and movement restrictions, and a decreasing proportion of costs associated with testing costs. Consequential costs tend to be higher for dairy than beef herds but this is likely due to larger herd sizes for dairy.Overall we find the total farm costs of bTB surpass those compensated for by Government in Great Britain. This study contributes to the public-private cost-sharing debate as farmers bear some of the economic burden of a disease breakdown. The methodology and results presented are crucial for informed Government and farmer decision-making. The identification of potential risk factors in this study was challenging but is of relevance outside GB.

Identification and Characterisation of Nontuberculous Mycobacteria in African Buffaloes (Syncerus caffer), South Africa

Diagnosis of bovine tuberculosis (bTB) may be confounded by immunological cross-reactivity to Mycobacterium bovis antigens when animals are sensitised by certain nontuberculous mycobacteria (NTMs). Therefore, this study aimed to investigate NTM species diversity in African buffalo (Syncerus caffer) respiratory secretions and tissue samples, using a combination of novel molecular tools. Oronasal swabs were collected opportunistically from 120 immobilised buffaloes in historically bTB-free herds. In addition, bronchoalveolar lavage fluid (BALF; n = 10) and tissue samples (n = 19) were obtained during post-mortem examination. Mycobacterial species were identified directly from oronasal swab samples using the Xpert MTB/RIF Ultra qPCR (14/120 positive) and GenoType CMdirect (104/120 positive). In addition, all samples underwent mycobacterial culture, and PCRs targeting hsp65 and rpoB were performed. Overall, 55 NTM species were identified in 36 mycobacterial culture-positive swab samples with presence of esat-6 or cfp-10 detected in 20 of 36 isolates. The predominant species were M. avium complex and M. komanii. Nontuberculous mycobacteria were also isolated from 6 of 10 culture-positive BALF and 4 of 19 culture-positive tissue samples. Our findings demonstrate that there is a high diversity of NTMs present in buffaloes, and further investigation should determine their role in confounding bTB diagnosis in this species.

Whole Genome Sequencing in the Management of Non-Tuberculous Mycobacterial Infections

Infections caused by non-tuberculous mycobacteria (NTM) have been a public health problem in recent decades and contribute significantly to the clinical and economic burden globally. The diagnosis of infections is difficult and time-consuming and, in addition, the conventional diagnostics tests do not have sufficient discrimination power in species identification due to cross-reactions and not fully specific probes. However, technological advances have been made and the whole genome sequencing (WGS) method has been shown to be an essential part of routine diagnostics in clinical mycobacteriology laboratories. The use of this technology has contributed to the characterization of new species of mycobacteria, as well as the identification of gene mutations encoding resistance and virulence factors. Sequencing data also allowed to track global outbreaks of nosocomial NTM infections caused by M. abscessus complex and M. chimaera. To highlight the utility of WGS, we summarize recent scientific studies on WGS as a tool suitable for the management of NTM-induced infections in clinical practice.

Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys

Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.

Towards a unified generic framework to define and observe contacts between livestock and wildlife: a systematic review

Wild animals are the source of many pathogens of livestock and humans. Concerns about the potential transmission of economically important and zoonotic diseases from wildlife have led to increased surveillance at the livestock-wildlife interface. Knowledge of the types, frequency and duration of contacts between livestock and wildlife is necessary to identify risk factors for disease transmission and to design possible mitigation strategies. Observing the behaviour of many wildlife species is challenging due to their cryptic nature and avoidance of humans, meaning there are relatively few studies in this area. Further, a consensus on the definition of what constitutes a 'contact' between wildlife and livestock is lacking. A systematic review was conducted to investigate which livestock-wildlife contacts have been studied and why, as well as the methods used to observe each species. Over 30,000 publications were screened, of which 122 fulfilled specific criteria for inclusion in the analysis. The majority of studies examined cattle contacts with badgers or with deer; studies involving wild pig contacts with cattle or with domestic pigs were the next most frequent. There was a range of observational methods including motion-activated cameras and global positioning system collars. As a result of the wide variation and lack of consensus in the definitions of direct and indirect contacts, we developed a unified framework to define livestock-wildlife contacts that is sufficiently flexible to be applied to most wildlife and livestock species for non-vector-borne diseases. We hope this framework will help standardise the collection and reporting of contact data; a valuable step towards being able to compare the efficacy of wildlife-livestock observation methods. In doing so, it may aid the development of better disease transmission models and improve the design and effectiveness of interventions to reduce or prevent disease transmission.

One Health approach in the prevention and control of mycobacterial infections in Tanzania: lessons learnt and future perspectives

BACKGROUND

One Health (OH) is an integrated approach, formed inclusive of using multiple disciplines to attain optimal health for humans, animals, and the environment. The increasing proximity between humans, livestock, and wildlife, and its role in the transmission dynamics of mycobacterial infections, necessitates an OH approach in the surveillance of zoonotic diseases. The challenge remains as humans, livestock, and wildlife share resources and interact at various interfaces. Therefore, this review explores the potential of the OH approach to understand the impact of mycobacterial infections in Tanzania in terms of lessons learnt and future perspectives.

MATERIALS AND METHODS

Available literature on OH and mycobacterial infections in Tanzania was searched in PubMed, Google Scholar, and Web of Science. Articles on mycobacterial infections in Tanzania, published between 1997 to 2017, were retrieved to explore the information on OH and mycobacterial infections.

MAIN BODY

The studies conducted in Tanzania had have reported a wide diversity of mycobacterial species in humans and animals, which necessitates an OH approach in surveillance of diseases for better control of infectious agents and to safeguard the health of humans and animals. The close proximity between humans and animals increases the chances of inter-specific transmission of infectious pathogens, including drug-resistant mycobacteria. In an era where HIV co-infection is also the case, opportunistic infection by environmental non-tuberculous mycobacteria (NTM), commonly known as mycobacteria other than tuberculosis (MOTT) may further exacerbate the impact of drug resistance. NTM from various sources have greatest potential for diverse strains among which are resistant strains due to continued evolutional changes.

CONCLUSION

A collaborative interdisciplinary approach among professionals could help in solving the threats posed by mycobacterial infections to public health, particularly by the spread of drug-resistant strains.

Prevalence of Mycobacterium bovis infection in traditionally managed cattle at the wildlife-livestock interface in South Africa in the absence of control measures

Cattle are the domestic animal reservoir for Mycobacterium bovis (M. bovis) which also affects other domestic animals, several wildlife species and humans leading to tuberculosis. The study area is in a resource-poor community that is surrounded by several game parks, where M. bovis infection has been previously diagnosed in wildlife. A cross-sectional study was carried out to determine the prevalence of M. bovis infection in 659 cattle from a total of 192 traditionally managed herds using the BOVIGAM® interferon gamma assay (IFN-γ). Infection was confirmed by post mortem examination and M. bovis isolation from three test-positive cattle. Genotyping of the M. bovis isolates was done using spoligotyping and VNTR (variable number of tandem repeats typing). The apparent M. bovis prevalence rate in cattle at animal level was 12% with a true population prevalence of 6% (95% Confidence interval (C.I) 3.8 to 8.1) and a herd prevalence of 28%. Spoligotyping analysis revealed that the M. bovis isolates belonged to spoligotype SB0130 and were shared with wildlife. Three VNTR profiles were identified among the SB0130 isolates from cattle, two of which had previously been detected in buffalo in a game reserve adjacent to the study area. The apparent widespread presence of M. bovis in the cattle population raises a serious public health concern and justifies further investigation into the risk factors for M. bovis transmission to cattle and humans. Moreover, there is an urgent need for effective bTB control measures to reduce infection in the communal cattle and prevent its spread to uninfected herds.

Prevalence of bovine tuberculosis in the Aksu Region of Xinjiang, China, between 1985 and 2016

ABSTRACT Prevalence of bovine tuberculosis infection in cattle in Aksu Prefecture determined by intradermal tuberculin skin test (TST), between 1985 and 2016. Cattle were analyzed according to region, feeding pattern, herds and age. A total of 890,009 cattle were tested, with overall bovine tuberculosis prevalence of 0.13% (1172/890009). Statistically significant difference was found in feeding pattern and herds. Prevalence in cows (0.19%, 615/327022) was higher than that in beeves (P< 0.01, OR= 1.903, 95% CI = 1.696 to 2.134). Significant difference (P< 0.01; OR= 2.238, 95%; CI= 1.937 to 2.585) was evident for rates for bovine tuberculosis in the peasant household (0.12%, 942/802343) and farm groups (0.26%, 230/87666). The overall prevalence of bTB was decreased in the Aksu Prefecture, especially the positive rate was under 0.1% in 2010s. We concluded that the control measures forbovine tuberculosis in the Aksu region cattle herds are effective.

Risk factors assessment of bovine tuberculosis among abattoir personnel in Gombe State, Northeastern Nigeria: A One-Health approach

Aim: Bovine tuberculosis (bTB) is an important milk-borne zoonosis that affects cattle production and poses serious threat to public health. This study aimed at assessing the risk factors as well as the level of awareness, attitude, and practices of abattoir personnel toward bTB in Gombe Township Abattoir, Gombe State. Materials and Methods: A prospective survey was conducted between October 2015 and December 2015. During the survey, a total of 112 close-ended structured questionnaires were administered to the abattoir personnel to assess their level of awareness of bTB. Results: Of these respondents, the majority were males (79%), butchers (49%) and about 40% were under the productive age brackets of 26-35 years. Majority of the respondents (85.7%) were aware of the zoonotic nature of the disease. However, only a few of the respondents (44.6%) wear personal protective equipments (PPEs) clothes while handling or in contact with carcasses during the slaughtering process. Only a few among the respondents (24.1% and 31.2%) consumed unpasteurized milk and unaware of eating of improperly cooked meat as a risk factor of bTB, respectively. About 75.7% of the respondents believed that the habit of eating and drinking inside the abattoir and during slaughtering operations has no any significant effects on their health. The results obtained show a statistically significant association between respondents' awareness of bTB and their occupational status, duration of exposure to cattle carcasses, and knowledge about the disease (p<0.05); and the odds of being aware of bTB was 10.0, 5.07, and 4.2, respectively. Conclusion: This study demonstrates the need for public health authorities to intervene in bTB prevention and control through the creation of avenues for enlightenment on the zoonotic risk associated with bTB. The risk factors associated with bTB transmission as indicated by the personnel's practice and awareness levels in Gombe township abattoir are preventable through the use of PPEs clothing.

Prevalence and risk factors analysis of bovine tuberculosis in cattle raised in mixed crop-livestock farming system in Tigray region, Ethiopia

Bovine tuberculosis (BTB) is a disease of animal and public health importance in developing countries. In rural Ethiopia, there is potential for a shift in the epidemiologic of this disease driven by transformation of dairy industry. This includes gradual change from the traditional mixed crop-livestock husbandry practice to a semi-intensification system. It is therefore, essential to document the prevalence and risk factors of BTB to continuously update the designing and implementation of control and prevention strategies. Here, we present findings of a cross-sectional study on the prevalence and associated risk factors of BTB among cattle reared under mixed crop-livestock farming system in Tigray region, Ethiopia. A multistage purposive sampling approach was used to select districts, villages, herds and individual cattle. A total of 1,357 cattle from 310 herds were examined for BTB infection using a comparative intradermal tuberculin skin test (CIDT). Questionnaires were used to gather data on herd structure and herd management practices. A multilevel logistic mixed effect model was used to determine risk factors after accounting for clustering effect at three levels (village, herd and individual animal). Overall prevalence of BTB was 4.3% (95% CI = 3.4-5.6), with the highest prevalence recorded in Alamata district (5.6%) and lowest in Korem (1.6%). Multilevel logistic mixed effect model analysis identified exotic breed (OR = 3, p = 0.014), closed barn (OR = 2.6, p = 0.018), large herd size (OR = 2.6, p = 0.05) and purchase of cattle (OR = 2.1, p = 0.027) as important risk factors for BTB. Taken together, these findings suggest that the current dairy development program centred on the introduction of exotic and or crossed animals could have contributed to changing epidemiological situations of BTB in the study area.

The prevalence of brucellosis and bovine tuberculosis in ruminants in Sidi Kacem Province, Morocco

Bovine tuberculosis (BTB) and brucellosis are major endemic zoonoses in ruminants in Morocco that impact on both animal and human health. This study presents an assessment of the epidemiological and socioeconomic burden of bacterial zoonoses in Sidi Kacem Province in Northern Morocco from a cross-sectional survey of 125 cattle and/or small ruminant-owning households. In total, 1082 sheep and goats were examined from 81 households. The single intradermal comparative cervical test to screen for bovine tuberculosis was undertaken on 1194 cattle from 123 households and all cattle were blood sampled. Cattle and small ruminant sera were tested for brucellosis using the standard Rose Bengal Test (sRBT) and the modified Rose Bengal Test (mRBT). Bacteriology was performed on 21 milk samples obtained from cattle that were seropositive for brucellosis for isolation and phenotyping of circulating Brucella strains. Individual and herd prevalence for BTB in cattle of 20.4% (95% CI 18%-23%) and 57.7% (95% CI 48%-66%), respectively, were observed in this study. The prevalence of brucellosis in cattle at individual and herd level was 1.9% (95% CI 1.2%-2.8%) and 9% (95% CI 4.5%-1.5%), respectively. Brucella pathogens were isolated from three cattle milk samples and were identified as B. abortus using Bruceladder® multiplex PCR and B. abortus biovar 1 by classical phenotyping. All small ruminants were seronegative to sRBT, two were positive to mRBT. A higher risk of BTB and brucellosis was observed in cattle in intensive livestock systems, in imported and crossed breeds and in animals from larger herds (>15). The three risk factors were usually present in the same herds, leading to higher transmission risk and persistence of both zoonoses. These results highlight the importance of implementing control strategies for both BTB and brucellosis to reduce productivity losses and the risk of transmission to humans. Prioritising control for BTB and brucellosis in intensive livestock production systems is essential for human and animal health.

SCREENING FOR BOVINE TUBERCULOSIS IN AFRICAN BUFFALO (SYNCERUS CAFFER) IN NGORONGORO CONSERVATION AREA, NORTHERN TANZANIA: IMPLICATIONS FOR PUBLIC HEALTH

In the Ngorongoro Conservation Area (NCA), Tanzania, where wildlife and livestock interaction is intense, greater potential for intra- and interspecies disease transmission is expected. We assessed the prevalence of bovine tuberculosis in African buffalo (Syncerus caffer) residing on the valley floor of the crater in the NCA. Apparently healthy animals were randomly selected from herds in nine sites of the Ngorongoro Crater. Syncerus caffer buffalo herds were located using very high-frequency radio-aided rangers positioned in various observation points around the crater in the NCA. A total of 102 African buffalo from 16 herds were immobilized from the ground using a cocktail of 4-10 mg etorphine hydrochloride (M99) and 60-150 mg azaperone tartrate. The M99 was reversed using 10-25 mg diprenorphine hydrochloride depending on age of animals. An interferon gamma assay was performed on harvested plasma samples using sandwich enzyme linked immunosorbent assay. Of the 102 animals sampled, two (2%) African buffalo tested positive for bovine tuberculosis. These results corroborate those of the skin test done recently in cattle in the NCA. The presence of bovine tuberculosis in livestock and wildlife suggested the possibility of cross-species transmission of the disease, indicating the need for appropriate intervention measures.

Isolation and Potential for Transmission of Mycobacterium bovis at Human-livestock-wildlife Interface of the Serengeti Ecosystem, Northern Tanzania

Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB), is a multihost pathogen of public health and veterinary importance. We characterized the M. bovis isolated at the human-livestock-wildlife interface of the Serengeti ecosystem to determine the epidemiology and risk of cross-species transmission between interacting hosts species. DNA was extracted from mycobacterial cultures obtained from sputum samples of 472 tuberculosis (TB) suspected patients and tissue samples from 606 livestock and wild animal species. M. bovis isolates were characterized using spoligotyping and Mycobacterial Interspersed Repetitive Units-Variable Tandem Repeats (MIRU-VNTR) on 24 loci. Only 5 M. bovis were isolated from the cultured samples. Spoligotyping results revealed that three M. bovis isolates from two buffaloes (Syncerus caffer) and 1 African civet (Civettictis civetta) belonged to SB0133 spoligotype. The two novel strains (AR1 and AR2) assigned as spoligotype SB2290 and SB2289, respectively, were identified from indigenous cattle (Bos indicus). No M. bovis was detected from patients with clinical signs consistent with TB. Of the 606 animal tissue specimens and sputa of 472 TB-suspected patients 43 (7.09%) and 12 (2.9%), respectively, yielded non-tuberculous mycobacteria (NTM), of which 20 isolates were M. intracellulare. No M. avium was identified. M. bovis isolates from wildlife had 45.2% and 96.8% spoligotype pattern agreement with AR1 and AR2 strains, respectively. This finding indicates that bTB infections in wild animals and cattle were epidemiologically related. Of the 24 MIRU-VNTR loci, QUB 11b showed the highest discrimination among the M. bovis strains. The novel strains obtained in this study have not been previously reported in the area, but no clear evidence for recent cross-species transmission of M. bovis was found between human, livestock and wild animals.

Tuberculosis Infection: Occurrence and Risk Factors in Presumptive Tuberculosis Patients of the Serengeti Ecosystem in Tanzania

Background

Cross-species tuberculosis (TB) transmission between humans and animals has been reported for quite a long time in sub-Saharan Africa. Because humans and animals coexist in the same ecosystem, exploring their potential for cross-species transmission and the impact the disease may have on the health of humans, animals, and their products is critical.

Objectives

This study aimed to identify risk factors for transmission of TB (Mycobacterium tuberculosis) and to assess the potential for zoonotic TB (Mycobacterium bovis) transmission in the Serengeti ecosystem where humans and animals are in intense contact. Our aim is to create a base for future implementation of appropriate control strategies to limit infection in both humans and animals.

Methodology

We administered a semi-structured questionnaire to 421 self-reporting patients to gather information on risk factors and TB occurrence. In a parallel study, researchers screened sputum smears using Ziehl-Neelsen staining and confirmed by mycobacterial culture. We then performed descriptive statistics (Pearson's chi-square test) and logistic regression analysis to establish frequencies, association, and quantification of the risk factors associated with TB cases.

Results

Our findings showed 44% (95% confidence interval [CI], 0.40-0.49) of the results were positive from sputum samples collected over a 1-year duration in areas with a high TB burden, particularly the Bunda district, followed by the Serengeti and Ngorongoro districts. Of the culture-positive patients who also had infections other than TB (43/187 patients), 21 (49%) were HIV positive. Contact with livestock products (odds ratio [OR] 6.0; 95% CI, 1.81-19.9), infrequent milk consumption (OR 2.5; 95% CI, 1.42-4.23), cigarette smoking (OR 2.9; 95% CI, 1.19-7.1.2), and alcohol consumption (OR 2.3; 95% CI, 1.22-4.23) were associated with a higher likelihood of TB infection.

Conclusion

There was no evidence of direct cross-species transmission of either M tuberculosis or M bovis between humans and animals using the study methods. The absence of cross-species TB transmission could be due to limited chances of contact rather than an inability of cross-species disease transmission. In addition, not all people with presumptive TB are infected with TB, and therefore control strategies should emphasise confirming TB status before administering anti-TB drugs.

Prevalence of tuberculosis, brucellosis and trypanosomiasis in cattle in Tanzania: a systematic review and meta-analysis

A meta-analysis was performed to derive prevalence estimates for Brucella spp., Mycobacterium spp. and Trypanosoma spp. in cattle in Tanzania using data derived from a systematic review of zoonotic hazards in cattle production systems. Articles published before 2012 reporting prevalence and considered at least moderate in quality were included in the analysis. Results showed high heterogeneity between studies, with wide ranges in the reported prevalence: Brucella (0.3–60.8%), Mycobacterium (0.1–13.2%) and Trypanosoma (0.82–33.3%). Overall meta-analytic mean prevalence estimates were 8.2% (95% CI 6.5–10.2), 1.28% (95% CI 0.35–4.58) and 10.3% (95% CI 6.20–16.70) respectively, for Brucella spp., Mycobacterium spp. and Trypanosoma spp. Time and region were predictors of variability of Brucella spp. prevalence, while diagnostic test was a strong predictor of Mycobacterium spp. prevalence, with higher prevalence estimates given by skin tests compared with post-mortem inspection. None of the studied factors were associated with prevalence of Trypanosoma spp. The small sample sizes, range of study locations, study designs and diagnostics used, contributed to high variability among prevalence estimates. Larger and more robust prevalence studies are needed to adequately support risk assessment and management of animal and public health threats.

Risk Factors for Bovine Tuberculosis (bTB) in Cattle in Ethiopia

Bovine tuberculosis (bTB) infection is generally correlated with individual cattle's age, sex, body condition, and with husbandry practices such as herd composition, cattle movement, herd size, production system and proximity to wildlife-including bTB maintenance hosts. We tested the correlation between those factors and the prevalence of bTB, which is endemic in Ethiopia's highland cattle, in the Afar Region and Awash National Park between November 2013 and April 2015. A total of 2550 cattle from 102 herds were tested for bTB presence using the comparative intradermal tuberculin test (CITT). Data on herd structure, herd movement, management and production system, livestock transfer, and contact with wildlife were collected using semi-structured interviews with cattle herders and herd owners. The individual overall prevalence of cattle bTB was 5.5%, with a herd prevalence of 46%. Generalized Linear Mixed Models with a random herd-effect were used to analyse risk factors of cattle reactors within each herd. The older the age of the cattle and the lower the body condition the higher the chance of a positive bTB test result, but sex, lactation status and reproductive status were not correlated with bTB status. At herd level, General Linear Models showed that pastoral production systems with transhumant herds had a higher bTB prevalence than sedentary herds. A model averaging analysis identified herd size, contact with wildlife, and the interaction of herd size and contact with wildlife as significant risk factors for bTB prevalence in cattle. A subsequent Structural Equation Model showed that the probability of contact with wildlife was influenced by herd size, through herd movement. Larger herds moved more and grazed in larger areas, hence the probability of grazing in an area with wildlife and contact with either infected cattle or infected wildlife hosts increased, enhancing the chances for bTB infection. Therefore, future bTB control strategies in cattle in pastoral areas should consider herd size and movement as important risk factors.

Prevalence and risk factors of bovine tuberculosis in dairy cattle in Eritrea

Background

The prevalence of bovine tuberculosis (BTB) in dairy cattle in the three major milk producing regions of Eritrea was assessed by subjecting 15,354 dairy cattle, 50 % of Eritrea’s dairy cattle population, to the single intradermal comparative tuberculin test (SICTT). Skin test results were interpreted according to guidelines of the World Organization for Animal Health (OIE) with >4 mm as cutoff in skin thickness increase. In addition, we studied the relation between ‘physiological’ variables related to pregnancy and lactation, and the variable ‘region’ on the probability to be skin test positive.

Results

The BTB prevalences at animal and herd levels were: 21.5 % and 40.9 % in Maekel, 7.3 % and 10 % in Debub, and 0.2 % and 1.6 % in the Anseba region, respectively. Overall, in the regions included, prevalence was 11.3 % (confidence interval (CI) 95 % CI, 11.29 – 11.31 %) and 17.3 % (95 % CI, 17.27–17.33 %), at animal and herd level, respectively. Considering positive herds only, the animal BTB prevalence was 36.8 %, 30.1 %, and 1.8 %, in Maekel, Debub and Anseba, respectively, and the overall animal prevalence within these herds was 32 %. In adult dairy cattle the probability of positive reactivity in the SICTT test was highest in pregnant animals as compared to the other categories.

Conclusion

This study reports persistent prevalence of BTB as defined by positive SICTT in the dairy sector of Eritrea, especially in the regions of Maekel and Debub that are located in the central highlands of the country. To our understanding this is the first report that has encompassed all the major dairy farms in Eritrea and it will be instrumental in advocating future BTB control programs in the dairy sector.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0705-9) contains supplementary material, which is available to authorized users.

Modelling the role of multi-transmission routes in the epidemiology of bovine tuberculosis in cattle and buffalo populations

A mathematical model that describes the transmission dynamics of bovine tuberculosis (BTB) in both buffalo and cattle populations is proposed. The model incorporates cross-infection and contaminated environment transmission routes. A full analysis of the model is undertaken. The reproduction number of the entire model is comprised of cross-infection and contaminated parameters. This underscores the importance of including both cross-infection and contaminated environment transmission routes. Crucially our simulations suggest that the disease has a more devastating effect on cattle populations than on buffalo populations when all transmission routes are involved. This has important implications for agriculture and tourism.

Molecular detection of Mycobacterium bovis in cattle herds of the state of Pernambuco, Brazil

Background

The present study aimed to direct detect Mycobacterium bovis in milk (n = 401) and blood (n = 401) samples collected from 401 dairy cows of 20 properties located in the state of Pernambuco, Brazil, by real-time quantitative PCR (qPCR) targeting the region of difference 4 (RD4). Risk factors possibly associated with bovine tuberculosis (BTB) were also evaluated.

Results

Of the 802 samples analyzed, one milk (0.25 %) and eight blood (2 %) samples were positive for M. bovis in the qPCR and their identities were confirmed by sequencing. Animals positive for M. bovis were found in six (30 %) of the 20 properties visited. None of the risk factors evaluated were statistically associated with BTB.

Conclusions

M. bovis DNA was detected in one milk sample what may pose a risk to public health because raw milk is commonly consumed in Brazil.

Spatial predictors of bovine tuberculosis infection and Brucella spp. exposure in pastoralist and agropastoralist livestock herds in the Ruaha ecosystem of Tanzania

While many studies investigate animal-related risk factors for disease, few have considered environmental or spatial risk factors in the dynamics of bovine tuberculosis (bTB) and brucellosis. In the Ruaha ecosystem of Tanzania, we investigated the role of household location as a predictor for infection with Mycobacterium bovis and exposure to Brucella in pastoralist and agropastoralist cattle herds in a typical African wildlife-livestock-human interface. ArcGIS was utilized to calculate Euclidian distances between households and the nearest river, village center, protected area, and other infected households, followed by multivariate logistic regression to assess the association between risk factors and herd-level bTB and Brucella outcomes. Global and local spatial clustering of bTB-infected and Brucella-exposed herds was explored using the Cuzick-Edward’s test and SaTScan spatial scan statistics. Households located farther from rivers and closer to village centers and herds belonging to agropastoralists were more likely to have bTB-positive cattle. Risk of Brucella exposure increased with proximity to protected areas. One spatial cluster of households with Brucella spp. seropositive cattle was identified. Spatial factors may be useful for assessing disease risk and for formulating intervention and control strategies for households that manage cattle in ecosystems characterized by seasonally limited resources and intense wildlife-livestock interfaces.

Genetic diversity of Mycobacterium tuberculosis isolated from tuberculosis patients in the Serengeti ecosystem in Tanzania

This study was part of a larger cross-sectional survey that was evaluating tuberculosis (TB) infection in humans, livestock and wildlife in the Serengeti ecosystem in Tanzania. The study aimed at evaluating the genetic diversity of Mycobacterium tuberculosis isolates from TB patients attending health facilities in the Serengeti ecosystem. DNA was extracted from 214 sputum cultures obtained from consecutively enrolled newly diagnosed untreated TB patients aged ≥18 years. Spacer oligonucleotide typing (spoligotyping) and Mycobacterium Interspersed Repetitive Units and Variable Number Tandem Repeat (MIRU-VNTR) were used to genotype M. tuberculosis to establish the circulating lineages. Of the214 M. tuberculosis isolates genotyped, 55 (25.7%) belonged to the Central Asian (CAS) family, 52 (24.3%) were T family (an ill-defined family), 38 (17.8%) belonged to the Latin American Mediterranean (LAM) family, 25 (11.7%) to the East-African Indian (EAI) family, 25 (11.7%) comprised of different unassigned (‘Serengeti’) strain families, while 8 (3.7%) belonged to the Beijing family. A minority group that included Haarlem, X, U and S altogether accounted for 11 (5.2%) of all genotypes. MIRU-VNTR typing produced diverse patterns within and between families indicative of unlinked transmission chains. We conclude that, in the Serengeti ecosystem only a few successful families predominate namely CAS, T, LAM and EAI families. Other types found in lower prevalence are Beijing, Haarlem, X, S and MANU. The Haarlem, EAI_Somalia, LAM3 and S/convergent and X2 subfamilies found in this study were not reported in previous studies in Tanzania.

Species diversity of non-tuberculous mycobacteria isolated from humans, livestock and wildlife in the Serengeti ecosystem, Tanzania

BACKGROUND

Non-tuberculous mycobacteria (NTM), which are ubiquitous micro-organisms occurring in humans, animals and the environment, sometimes receive public health and veterinary attention as opportunistic disease-causing agents. In Tanzania, there is limited information regarding the diversity of NTM species, particularly at the human-livestock-wildlife interface such as the Serengeti ecosystem, where potential for cross species infection or transmission may exist.

METHODS

Mycobacterial DNA was extracted from cultured isolates obtained from sputum samples of 472 suspect TB patients and 606 tissues from wildlife species and indigenous cattle. Multiplex PCR was used to differentiate NTM from Mycobacterium tuberculosis complex (MTBC) members. NTM were further identified to species level by nucleotide sequencing of the 16S rRNA gene.

RESULTS

A total of fifty five (55) NTM isolates representing 16 mycobacterial species and 5 isolates belonging to the MTBC were detected. Overall, Mycobacterium intracellulare which was isolated from human, cattle and wildlife, was the most frequently isolated species (20 isolates, 36.4%) followed by M. lentiflavum (11 isolates, 20%), M. fortuitum (4 isolates, 7.3%) and M. chelonae-abscessus group (3 isolates, 5.5%). In terms of hosts, 36 isolates were from cattle and 12 from humans, the balance being found in various wildlife species.

CONCLUSION

This study reveals a diversity of NTM species in the Serengeti ecosystem, some of which have potential for causing disease in animals and humans. The isolation of NTM from tuberculosis-like lesions in the absence of MTBC calls for further research to elucidate their actual role in causing disease. We are also suggesting a one health approach in identifying risk factors for and possible transmission mechanisms of the NTM in the agro-pastoral communities in the Serengeti ecosystem.