Risk factors of bovine tuberculosis in cattle in rural livestock production systems of Ethiopia

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.

Analysis of Dietary and Nutritional Status of Tuberculosis Patients in Hulunbuir Region

Objective

Tuberculosis (TB) is a major public health problem that affects millions of people worldwide. Malnutrition is a common complication of TB and can worsen the disease outcome. The purpose of this study was to investigate the dietary and nutritional status, as well as the dietary structure, of TB patients in Hulunbuir City, Inner Mongolia, China. Additionally, the study aimed to analyze the factors that influence the nutritional status in order to provide a theoretical foundation for the prevention and treatment of TB and related issues.

Methods

A cross-sectional study was conducted on 334 randomly selected TB patients from Hulunbuir City Second Hospital. A questionnaire survey was administered to collect information on demographic characteristics, dietary habits, and food intake. Nutritional status was assessed by body mass index (BMI). Dietary diversity score (DDS) was calculated based on the number of food groups consumed in the previous 24 hours. Statistical analysis was performed using SPSS 20.0 software. Descriptive statistics employed rates and composition ratios, and categorical data was represented using frequencies and percentages. The chi-square test was used to analyze the association between nutritional status and other variables, with a significance level set at α=0.05. Multivariable ordinal logistic regression analysis was performed to identify the independent factors affecting the nutritional status of TB patients.

Results

The univariate analysis revealed statistically significant differences (P < 0.05) in the nutritional status (as measured by BMI) among tuberculosis patients, considering ethnicity, educational level, smoking, meat-based diet, vegetable consumption, and DDS grading. No statistically significant differences were found regarding gender, age, marital status, occupation, sleep duration, alcohol consumption, and consumption of rice and flour dishes. Statistically significant variables from the univariate analysis were included in a multivariable ordinal logistic regression analysis model. The findings highlighted that educational level (high school or below), smoking, meat-based diet, DDS scores of 1-3, and a primarily vegetable-based diet had independent effects on the nutritional status of tuberculosis patients (all P < 0.05). No significant difference was found in nutritional status between the Han ethnic group and other ethnicities.

Conclusion

The study revealed that the dietary and nutritional status of TB patients in Hulunbuir City was suboptimal and influenced by several factors. Smoking, meat-based diet, and low dietary diversity score were the primary risk factors for malnutrition among TB patients. The study suggests that nutritional education and intervention programs should be implemented for TB patients to improve their dietary quality and nutritional status.

Gut Microbiome Profiling of the Endangered Southern Greater Glider (Petauroides volans) after the 2019-2020 Australian Megafire

Studying the gut microbiome can provide valuable insights into animal health and inform the conservation management of threatened wildlife. Gut microbiota play important roles in regulating mammalian host physiology, including digestion, energy metabolism and immunity. Dysbiosis can impair such physiological processes and compromise host health, so it is essential that the gut microbiome be considered in conservation planning. The southern greater glider (Petauroides volans) is an endangered arboreal marsupial that faced widespread habitat fragmentation and population declines following the 2019-2020 Australian bushfire season. This study details baseline data on the gut microbiome of this species. The V3-V4 region of the 16S rRNA gene was amplified from scats collected from individuals inhabiting burnt and unburnt sites across southeastern Australia and sequenced to determine bacterial community composition. Southern greater glider gut microbiomes were characterised by high relative abundances of Firmicutes and Bacteroidota, which is consistent with that reported for other marsupial herbivores. Significant differences in gut microbial diversity and community structure were detected among individuals from different geographic locations. Certain microbiota and functional orthologues were also found to be significantly differentially abundant between locations. The role of wildfire in shaping southern greater glider gut microbiomes was shown, with some significant differences in the diversity and abundance of microbiota detected between burnt and unburnt sites. Overall, this study details the first data on greater glider (Petauroides) gut microbiomes, laying the foundation for future studies to further explore relationships between microbial community structure, environmental stressors and host health.

Factors determining family and social support among pulmonary tuberculosis patients in East Khasi Hills, Meghalaya: a cross-sectional study

INTRODUCTION

Family support plays a vital role in the outcome of individuals with tuberculosis (TB).

OBJECTIVES

To determine the family and social support among individuals with pulmonary TB during treatment.

METHODS

A cross-sectional survey was conducted among 237 pulmonary TB patients currently in the continuous phase of treatment. Bivariate and multivariate analyses were conducted to determine the association and predictors for family and social support. P-value < 0.05 was considered statistically significant.

RESULTS

The mean age of the respondents was 31.97 ± 12.51 years, and a majority (58.2%) of the respondents with TB disease were 18 to 38 years old, and 59.9% were males. Around 49.7% of the pulmonary TB patients received a high level of family support, whereas 73% received a high level of social support. The determinants like age, average monthly income, the educational level of the head of the family and the occupational level of both the patients and the head of the family are associated with family support.

CONCLUSION

This study recommends a coordinated strategy to treat TB that involves not only professional services but also the vital social support network of family and community that is required throughout therapy.

Assessment of Knowledge, Attitudes, and Practices (KAP): Public Health and Economic Burden of Tuberculosis in Jarso District of West Wollega Zone, Oromia, Western Ethiopia

Tuberculosis is a communicable mycobacterial disease of humans and animals caused by members of Mycobacterium tuberculosis complex, highly impacting the public health and economy of the country in endemic areas. Retrospective and cross-sectional study was conducted between March and August 2021. For knowledge, attitude, and practices study, five villages were randomly selected using simple random sampling. To quantify the public health burden, one-year data were collected from Jarso Health Center, and unregistered patients were identified using snowball method, and the estimation was based on disability-adjusted life years. Younger age groups (18-40 years) had shown 105.8 times more odds of knowledge towards tuberculosis than the older (>60 years). Moreover, tertiary levels of education had 9395.1 times more odds of knowledge towards tuberculosis compared to illiterates. The estimated economic burden was 7,731.25US$. Of the 51 tuberculosis patients, two died from the disease, resulting in 45.03 disability-adjusted life years. Communities of the study district were heard about tuberculosis, however, unaware of the cause and sources of the infection. Therefore, further strategic and continuous community-based health education and awareness should be given for effective control and prevention of tuberculosis in the study area.

Field evaluation of the tuberculin skin test for the detection of Mycobacterium tuberculosis complex infection in communal goats (Capra hircus) in KwaZulu-Natal, South Africa

In South Africa, animal tuberculosis (TB) control programs predominantly focus on domestic cattle and African buffaloes (Syncerus caffer) despite increasing global reports of tuberculosis in goats (Capra hircus). Left undetected, Mycobacterium tuberculosis complex (MTBC) infected goats may hinder TB eradication efforts in cattle and increase zoonotic risk to humans. Since the publication of animal TB testing guidelines in 2018, prescribing the use of the tuberculin skin test (TST) for goats in South Africa by the Department of Agriculture, Land Reform, and Rural Development (DALRRD), there have been no published reports of any field application of the prescribed test criteria in goat herds. Therefore, this study aimed to evaluate the performance of these DALRRD guidelines using the single intradermal cervical tuberculin test (SICT) and the single intradermal comparative cervical tuberculin test (SICCT). Between October and December 2020, 495 goats from communal pastures of Kwa-Zulu Natal (KZN), where M. bovis infection has been identified in cattle and where cattle and goats cohabitate, were tested using the SICT and SICCT (M. bovis-exposed group). Additionally, 277 goats from a commercial Saanen dairy herd, with no history of M. bovis, were also tested (M. bovis-unexposed group). Estimated apparent prevalence of TST positive goats was determined based on published test interpretation criteria as described by DALRRD. When proportions of test-positive goats were compared between different DALRRD criteria, the ≥ 4 mm cut-off criterion for the SICCT resulted in the lowest proportion of positive results in the presumably uninfected group (1/277 positive in the unexposed group). The apparent prevalence of TB in the exposed group was estimated at 3.0% (95% CI: 1.7-4.9%), which is similar to previous reports of M. bovis prevalence in cattle from this area (6%). The detection of a significantly greater proportion of SICCT positive goats in the M. bovis-exposed group compared to the unexposed group suggests that MTBC infection is present in this population. Further investigations should be undertaken, in conjunction with confirmatory molecular tests, mycobacterial culture, and advanced pathogen sequencing to establish whether MTBC infection in domestic goats is a true under-recognized threat to the eradication of animal TB in South Africa.

Public Awareness, Prevalence and Potential Determinants of Bovine Tuberculosis in Selected Districts of Gamo Zone, Southern Ethiopia

Purpose

Bovine tuberculosis (bTB) is infectious chronic disease of animals mainly caused by bacillus Mycobacterium bovis. It is known endemic disease of cattle in Ethiopia. In the current study sites, there is little information on bovine tuberculosis. Thus, this study was aimed to assess public awareness; and estimate prevalence and potential a risk factors of bovine tuberculosis.

Methods

A cross-sectional study was conducted, November 2018 to May 2019, on dairy cattle randomly selected from smallholder farms of Arba Minch Zuria and Chencha districts. Comparative intradermal tuberculin test (CIDT) was used in the diagnosis of bTB in dairy animals. CIDT was administered to 221 dairy cattle. Questionnaire survey was performed on 110 smallholders to assess risk factors accountable for the event of bTB in human population.

Results

8.2% animal level prevalence of bTB was documented in the study sites. Dairy cattle with age of 4 to 8 eight years were 34% more likely to be affected by bTB less than 4 years age cattle (OR=1.34). However, factors like housing, body condition, herd size and parity were not significantly related with the event of bTB. The assessment of bTB awareness was shown 29.7% participants knew that cattle could be infected, and 13.4% of the respondents believed that it can spread from animal to human and vice versa. Besides, 66.1% of participants had habit for consumption of raw milk and soured milk products. Moreover, respondent’s attitude about zoonoses and consequences of bTB was risky.

Conclusion

Present study discloses that bTB is animal health problem affecting dairy cattle in Gamo zone, Southern Ethiopia. Based on the current findings, public awareness creation, bovine tuberculosis test and segregation strategy should be applied to minimize the public health hazards and risk factors for bovine origin tuberculosis.

Histopathological Investigations and Molecular Confirmation Reveal Mycobacterium bovis in One-Horned Rhinoceros (Rhinoceros unicorns)

Mycobacterium bovis causes tuberculosis in dairy and wild animals. Presence of tuberculosis in animals poses a threat not only to their herd mates but also for public. No reports are available about the clinical, pathological, and molecular investigation of naturally occurring tuberculosis (TB) due to M. bovis in one-horned rhinoceros. One-horned female rhinoceros (Rhinoceros unicorns) at the age of 41 years died in a public park in Pakistan. Postmortem and other investigations were carried out to know the cause of death. The present study describes necropsy, histopathology, and molecular-based confirmation of TB in a captive female rhinoceros that died of this infection. Clinically, the rhinoceros showed nonspecific clinical signs including anorexia, lethargy, dyspnoea, coughing, and sudden death. At necropsy, the trachea exhibited mild congestion and contained catarrhal exudate at the bronchial bifurcation. Macroscopic examination revealed characteristic tubercles on all parenchymatous organs. The lungs showed consolidation, grey hepatization, and contained granulomatous lesions packed with cheesy exudate. Histopathological examination showed severe pneumonic changes in the form of granulomatous inflammation consisting of lymphocytes, multinucleated giant cells, caseous materials, and mineralized foci surrounded by a fibrous capsule. PCR amplicon of 500 bp confirmed the presence of M. bovis in multiple hepatic and pulmonary tissue samples, as well as in uterine exudates. It was concluded that the presence of tuberculosis in rhinoceros may pose potential transmission risk to other animals and the application of practical tools to determine TB status in the rhinoceros is crucial.

Prevalence of bovine tuberculosis and distribution of tuberculous lesions in cattle slaughtered at Gondar, Northwest Ethiopia

Background

In Ethiopia, bovine tuberculosis (BTB) is a neglected disease that affects the economy and livelihoods of farmers. However, the available data is limited due to insufficient disease surveillance in the country. Therefore; this study aimed to assess the prevalence and distribution of lesions of BTB in cattle slaughtered at Gondar, Northwest Ethiopia.

Methods

Postmortem examinations were used to detect tuberculous lesions, while smear microscopy and histopathology were performed for the identification of acid-fast bacilli (AFB).

Results

Of 497 inspected slaughtered cattle, 45 (9.1%, 95%CI; 0.0668–0.1193) were diagnosed with BTB suggestive tuberculous lesions. A higher proportion of gross lesions was recorded in lymph nodes of lungs; at the mediastinal (14, 31.1%) and bronchial (10, 22.2%) lymph nodes, and followed by mesenteric lymph nodes (9, 20%). Of 45 tuberculous lesions; only 2 (4.4%) were identified as AFB positive by smear microscopy and histopathology. In the overall statistical analysis, body conditions of slaughtered cattle were found to be significantly associated with BTB tuberculous lesions (p < 0.05).

Conclusion

This finding provides the prevalence of BTB and distribution of tuberculous lesions in cattle slaughtered at the abattoir and highlights the need for a practicable control strategy of the disease in the region.

Bacteriological and molecular characterization of Mycobacterium bovis isolates from tuberculous lesions collected among slaughtered cattle, Northwest Ethiopia

Background

In Ethiopia, the distribution of bovine tuberculosis (BTB) has long been known and documented as a major problem of animal health. However, the burden of circulating M. bovis strains is poorly understood in the country. Therefore; this study aimed to identify and characterize the mycobacterial isolates responsible for BTB in Northwest Ethiopia.

Methods

A cross-sectional study was conducted on tuberculous lesions that had been collected from slaughtered cattle between September 2018 to June 2019. Collected lesions were cultured and tested for tuberculous bacilli. The MPT64 assay and Genotype line probe assay (LPA) were used for identification of mycobacterial isolates, and region of deletion 4 (RD4) typing and spoligotyping were used to characterize the M. bovis strains.

Results

Of the total 1458 examined slaughtered cattle, only 62 (4.3, 95%CI; 0.0328–0.0542) had tuberculous lesions. The highest number of gross tuberculous lesions were observed from the lymph nodes of the thoracic cavity; at the mediastinal (40.3%, 25/62) and bronchial (22.6%, 14/62) lymph nodes. Of the 62 collected tuberculous lesions; 18 (29.0%) were culture positive for mycobacterium isolates, and only five isolates were confirmed for M. tuberculosis complex (MTBc) by the MPT64 assay and LPA. All the five MTBc isolates were positive for RD4 typing of M. bovis with a PCR product size of 446 bp, and no isolate was noticed to have M. tuberculosis. The detected M. bovis strains displayed five spoligotypes; with the common SB1176 and SB0133 M. bovis strains, although the two spoligotypes had not been previously reported.

Conclusion

The present study shows that BTB in North Gondar, Ethiopia, is caused by M. bovis strains SB1176 and SB0033, with low frequency. Thus, the finding highlights the importance of continuous surveillance for mycobacterial strains in cattle populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02349-1.

Evaluation of the Efficacy of BCG in Protecting Against Contact Challenge With Bovine Tuberculosis in Holstein-Friesian and Zebu Crossbred Calves in Ethiopia

Bovine tuberculosis (bTB) is prevalent in intensive dairy farms in Ethiopia. Vaccination could be an alternative control approach given the socio-economic challenges of a test-and-slaughter control strategy. The efficacy of the BCG was evaluated on 40 Holstein-Friesian (HF) and zebu crossbred calves recruited from single intradermal cervical comparative tuberculin (SICCT) test negative herds and randomly allocated into two groups. Twenty-two calves were vaccinated within 2 weeks of age, and 18 were kept as a control. Six weeks post-vaccination, the two groups were exposed and kept mixed with known SICCT test positive cows for 1 year. Immune responses were monitored by interferon gamma (IFN-γ) release assay (IGRA), SICCT test, and antibody assay. Vaccinated calves developed strong responses to the SICCT test at the sixth week post-vaccination, but did not respond to ESAT-6/CFP-10 peptide antigen-based IGRA. During the exposure, IFN-γ response to the specific peptide cocktail [F_{(2.44, 92.67)} = 26.96; p < 0.001] and skin reaction to the specific proteins cocktail [F_{(1.7, 64.3)}; p < 0.001] increased progressively in both groups while their antibody responses were low. The prevalence of bTB was 88.9% (95% CI: 65.3–98.6) and 63.6% (95% CI: 40.7–83.8) in the control and vaccinated calves, respectively, based on Mycobacterium bovis isolation, giving a direct protective efficacy estimate of 28.4% (95% CI: −2.7 to 50.1). The proportion of vaccinated calves with lesion was 7.0% (34/484) against 11.4% (45/396) in control calves, representing a 38% (95% CI: 5.8–59.4) reduction of lesion prevalence. Besides, the severity of pathology was significantly lower (Mann–Whitney U-test, p < 0.05) in vaccinated (median score = 2.0, IQR = 0–4.75) than in control (median score = 5, IQR = 3.0–6.25) calves. Moreover, survival from M. bovis infection in vaccinated calves was significantly (log-rank test: χ² = 6.749, p < 0.01) higher than that of the control calves. In conclusion, the efficacy of BCG was low, but the reduced frequency and severity of lesion in vaccinated calves could suggest its potential role in containing onward transmission.

The variable prevalence of bovine tuberculosis among dairy herds in Central Ethiopia provides opportunities for targeted intervention

Bovine tuberculosis (bTB) is an important disease for dairy productivity, as well as having the potential for zoonotic transmission. Previous prevalence studies of bTB in the dairy sector in central Ethiopia have suggested high prevalence, however, they have been limited to relatively small scale surveys, raising concerns about their representativeness. Here we carried out a cross sectional one-stage cluster sampling survey taking the dairy herd as a cluster to estimate the prevalence of bTB in dairy farms in six areas of central Ethiopia. The survey, which to date is by far the largest in the area in terms of the number of dairy farms, study areas and risk factors explored, took place from March 2016 to May 2017. This study combined tuberculin skin testing and the collection of additional herd and animal level data by questionnaire to identify potential risk factors contributing to bTB transmission. We applied the single intradermal cervical comparative tuberculin (SICCT) test using >4mm cut-off for considering an individual animal as positive for bTB; at least one reactor animal was required for a herd to be considered bTB positive. Two hundred ninety-nine dairy herds in the six study areas were randomly selected, from which 5,675 cattle were tested. The overall prevalence of bTB after standardisation for herd-size in the population was 54.4% (95% CI 48.7–60%) at the herd level, and it was 24.5% (95% CI 23.3–25.8) at the individual animal level. A Generalized Linear Mixed Model (GLMM) with herd and area as random effect was used to explore risk factors association with bTB status. We found that herd size, age, bTB history at farm, and breed were significant risk factors for animals to be SICCT positive. Animals from large herds had 8.3 times the odds of being tuberculin reactor (OR: 8.3, p-value:0.008) as compared to animals from small herds. The effect of age was strongest for animals 8–10 years of age (the oldest category) having 8.9 times the odds of being tuberculin reactors (OR: 8.9, p-value:<0.001) compared to the youngest category. The other identified significant risk factors were bTB history at farm (OR: 5.2, p-value:0.003) and cattle breed (OR: 2.5, p-value: 0.032). Our study demonstrates a high prevalence of bTB in central Ethiopia but with a large variation in within-herd prevalence between herds, findings that lays an important foundation for the future development of control strategies.

Molecular characterization and antimicrobial resistance profiles of Mycobacterium tuberculosis complex in environmental substrates from three dairy farms in Eastern Cape, South Africa

This study analysed 330 environmental substrates from three dairy farms for the occurrence, drug resistance and the genetic mutations of MTBC (Mycobacterium tuberculosis complex) in Eastern Cape, South Africa using PCR, while the Genotype MTBDRplus assay was used for drug susceptibility and genetic mutations analyses. About 17% (55/330) of the samples were positive for MTBC at 16.7% (water), 13.3% (soil) and 20% (hayfeed). Isoniazid resistance was detected in 47.3% (26/55) of the samples while 16.4% (9/55) were multidrug-resistant. Genetic mutations were detected on the rpoB gene (resistance to rifampicin) with frequencies ranging from 53.6% (D516V) to 21.4% (H526D), while mutations on the katG and inhA genes (resistance to isoniazid) ranged between 14.3% and 80%. Incidents of diverse genetic mutations in the environmental matrices suggest possible resistance to other anti-TB drugs not assayed in this study and emphasizes the need for continuous monitoring of drug resistance patterns for timely detection and control of new clonal groups of MTBC.

Field Evaluation of the Interferon Gamma Assay for Diagnosis of Tuberculosis in Water Buffalo (Bubalus bubalis) Comparing Four Interpretative Criteria

Bovine tuberculosis (bTB) is a worldwide zoonosis that affects many species of domestic and wild animals. Mycobaterium bovis is the main cause of infection in water buffalo (Bubalus bubalis) and bovines and is of great concern for human health and for buffalo producers in Italy. The bTB eradication programme is based on slaughterhouse surveillance and intradermal skin tests. Other in vivo diagnostic methods such as the interferon-gamma (IFN-γ) assay have been developed and are widely used in cattle to accelerate the elimination of bTB positive animals. The present study is the first to assess the use and performance of IFN-γ assays, which is used as an ancillary test for bTB diagnosis in water buffalo, and presents the results of a field-evaluation of the assay from 2012 to 2019 during the buffalo bTB eradication programme in Italy. The study involved 489 buffaloes with a positive result to the single intradermal tuberculin test (SITT). The IFN-γ assays and single intradermal comparative tuberculin test were used as confirmation tests. Then, a total of 458 buffaloes, reared on officially tuberculosis-free (OTF) herds, that were confirmed bTB-free for at least the last 6 years were subjected to IFN-γ testing. Furthermore, to evaluate the IFN-γ test in an OTF herd with Paratuberculosis (PTB) infection, 103 buffaloes were subjected to SITT and IFN-γ test simultaneously. Four interpretative criteria were used, and the IFN-γ test showed high levels of accuracy, with sensitivity levels between 75.3% (CI 95% 71.2–79.0%) and 98.4% (CI 95% 96.7–99.4%) and specificity levels between 94.3% (CI 95% 91.2–96.50%) and 98.5% (CI 95% 96.9–99.4%), depending on the criterion used. Finally, in the OTF herd with PTB infection, in buffalo, the IFN-γ test displayed high specificity values according to all 4 interpretative criteria, with specificity levels between 96.7% (CI 95% 88.4–99.5%) and 100% (CI 95% 96.2–100%), while SITT specificity proved unsatisfactory, with a level of 45.3% (CI 95% 35.0–55.7%). Our results showed that the IFN-γ test in the buffalo species could reach high Sensitivity and Specificity values, and that the level of Sensitivity and Specificity could be chosen based on the interpretative criterion and the antigens used depending on the health status of the herd and the epidemiological context of the territory. The IFN-γ test and the use of different interpretative criteria proved to be useful to implement bTB diagnostic strategies in buffalo herds, with the possibility of a flexible use of the assay.

Bovine tuberculosis prevalence and risk factors in selected districts of Bangladesh

A cross-sectional survey was conducted in selected districts of Bangladesh to estimate the prevalence of bovine tuberculosis (bTB), and to identify the risk factors for bTB. We included 1865 farmed cattle from 79 herds randomly selected from five districts. Herd and animal level data were collected using semi-structured interviews with cattle herd owners. The single intradermal comparative tuberculin test (SICTT) was used to estimate the prevalence of bTB. The risk factors were identified using mixed-effect multiple logistic regression analyses. The overall herd and animal level prevalences of bTB were estimated to be 45.6% (95% Confidence Interval [CI] = 34.3–57.2%) and 11.3 (95% CI = 9.9–12.8%), respectively, using the OIE recommended >4 mm cut-off. The true animal level prevalence of bTB was estimated to be 11.8 (95% Credible Interval = 2.1–20.3%). At the herd level, farm size, bTB history of the farm and type of husbandry were significantly associated with bTB status in univariable analysis. Similarly, age group, sex, pregnancy status and parity were significantly associated with bTB at cattle level. However, in multivariable analysis only herd size at the herd level and age group and pregnancy status at the cattle level were significant. Compared to a herd size of 1–10, the odds of bTB were 22.8 (95% CI: 5.2–100.9) and 45.6 times (95% CI: 5.0–417.7) greater in herd sizes of >20–50 and >50, respectively. The odds of bTB were 2.2 (95% CI: 1.0–4.5) and 2.5 times (95% CI: 1.1–5.4) higher in cattle aged >3–6 years and > 6 years, compared to cattle aged ≤1 year. Pregnancy increased the odds of bTB by 1.7 times (95% CI: 1.2–2.4) compared to non-pregnant cattle. Taken together, the results suggest high herd and animal level prevalence of bTB in these 5 districts, with the greatest risk of bTB in older and pregnant cattle within large herds (>20), and highlight an urgent need for continued surveillance and implementation of bTB control programs in Bangladesh.

Tracing cross species transmission of Mycobacterium bovis at the wildlife/livestock interface in South Africa

BACKGROUND

Bovine tuberculosis (bTB) affects cattle and wildlife in South Africa with the African buffalo (Syncerus caffer) as the principal maintenance host. The presence of a wildlife maintenance host at the wildlife/livestock interface acting as spill-over host makes it much more challenging to control and eradicate bTB in cattle. Spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) genotyping methods were performed to investigate the genetic diversity of Mycobacterium bovis (M. bovis) isolates from cattle and wildlife, their distribution and transmission at the wildlife/livestock interface in northern Kwa-Zulu Natal (KZN), South Africa.

RESULTS

SB0130 was identified as the dominant spoligotype pattern at this wildlife/livestock interface, while VNTR typing revealed a total of 29 VNTR profiles (strains) in the KZN province signifying high genetic variability. The detection of 5 VNTR profiles shared between cattle and buffalo suggests M. bovis transmission between species. MIRU-VNTR confirmed co-infection in one cow with three strains of M. bovis that differed at a single locus, with 2 being shared with buffalo, implying pathogen introduction from most probably unrelated wildlife sources.

CONCLUSION

Our findings highlight inter and intra species transmission of bTB at the wildlife/livestock interface and the need for the implementation of adequate bTB control measures to mitigate the spread of the pathogen responsible for economic losses and a public health threat.

Risk practices for bovine tuberculosis transmission to cattle and livestock farming communities living at wildlife-livestock-human interface in northern KwaZulu Natal, South Africa

Bovine tuberculosis (bTB) is a disease of cattle that is transmitted through direct contact with an infected animal or ingestion of contaminated food or water. This study seeks to explore the local knowledge on bTB, obtain information on social and cultural practices regarding risk of bTB transmission to cattle and humans (zoonotic TB) in a traditional livestock farming community with a history of bTB diagnosis in cattle and wildlife. Information was collected using a qualitative approach of Focus Group Discussions (FGDs) targeting household members of livestock farmers that owned bTB tested herds. We conducted fourteen FGDs (150 individuals) across four dip tanks that included the following categories of participants from cattle owning households: head of households, herdsmen, dip tank committee members and women. The qualitative data was managed using NVivo Version 12 Pro software. Social and cultural practices were identified as major risky practices for bTB transmission to people, such as the consumption of undercooked meat, consumption of soured /raw milk and lack of protective measures during slaughtering of cattle. The acceptance of animals into a herd without bTB pre-movement testing following traditional practices (e.g. lobola, 'bride price', the temporary introduction of a bull for 'breeding'), the sharing of grazing and watering points amongst the herds and with wildlife were identified as risky practices for M. bovis infection transmission to cattle. Overall, knowledge of bTB in cattle and modes of transmission to people and livestock was found to be high. However, the community was still involved in risky practices that expose people and cattle to bovine TB. An inter-disciplinary 'One Health' approach that engages the community is recommended, to provide locally relevant interventions that allows the community to keep their traditional practices and socio-economic systems whilst avoiding disease transmission to cattle and people.

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.

Potential efficiency of conventional and advanced approaches used to detect Mycobacterium bovis in cattle

The present study was aimed to assess the prevalence and efficiency of techniques for the diagnosis of bovine tuberculosis (bTB) including enzyme-linked immunosorbent assay (ELISA), Gamma interferon assay (IFN-γ) and polymerase chain reaction (PCR) in comparison to skin tuberculin test and culture technique. A total of 2600 cross-breed dairy cattle in Menoufia and Daqahlia governorates were tested by the single intradermal tuberculin test where the disease prevalence was 1.8%. Serum and whole blood samples were collected from positive tuberculin reactors for ELISA and IFN-γ assay, respectively. After slaughtering of positive tuberculin reactors, the post-mortem examination was carried out and tissue samples were collected for the bacteriological examination and PCR. The percentage of visible lesions of tuberculin reactors was 78.7%, while non-visible lesions were 21.27%. Culture technique revealed that the percentage of bTB was 63.8%. The ELISA and IFN-γ assay using short-term culture filtrate (ST-CF) prepared antigen revealed higher sensitivity (72.3% and 82.9%) than the bovine purified protein derivative (PPD-B) antigen. Although prepared ST-CF antigen has great efficiency and eligibility for the diagnosis of bTB, PCR appeared to have a higher sensitivity (85.1%) than other diagnostic methods when dealing with post-mortem samples. Gamma interferon assay using ST-CF antigen is recommended for antemortem diagnosis of bTB in cattle.

Prevalence of bovine tuberculosis and its associated risk factors in the emerging dairy belts of regional cities in Ethiopia

Bovine tuberculosis (BTB) has become an economically important disease in dairy herds found in and around Addis Ababa City and is emerging in regional cities like Gondar, Hawassa and Mekelle because of the establishment of dairy farms in the milk sheds of these cities. A cross-sectional study to estimate the prevalence of BTB and identify associated risk factors was conducted between February 2016 and March 2017. A total of 174 herds comprising of 2,754 dairy cattle in the cities of Gondar, Hawassa and Mekelle were tested using the Single Intradermal Comparative Cervical Tuberculin (SICCT) test. Data on herd structure, animal origin, body condition, housing condition, farm hygiene, management and biosecurity practices were collected using a pre-tested structured questionnaire. Generalized Linear Models (GLM) and Generalized Linear Mixed Models (GLMM) were used to analyze the herd and animal level risk factors, respectively. The herd prevalence was 22.4% (95% CI: 17-29%) while the animal prevalence was 5.2% (95% CI: 4-6%) at the cut-off >4 mm. The herd prevalence rose to 65.5% (95% CI: 58-72%) and the animal prevalence rose to 9% (95% CI: 8-10%) when the severe interpretation of >2 mm cut-off was applied. The mean within-herd prevalence in positive farms at the cut-off >4 mm was 22.7% (95% CI: 15-31%). At the herd level, the analysis showed that herd size, farm hygiene, feeding condition and biosecurity were significantly associated with BTB status, while new cattle introductions showed only borderline significance and that age of farm, housing condition, farmers' educational status and animal health care practice were not significant. At the animal level, the results showed that age and animal origin were identified as significant predictors for BTB positivity but sex and body condition score were not related to BTB status. Descriptive analysis revealed that herds having 'BTB history' showed slightly higher likelihood of being BTB positive compared to farms having no previous BTB exposure. In conclusion, this study showed relatively lower average prevalence in the emerging dairy regions as compared to the prevalence observed in and around Addis Ababa City, warranting for implementation of control program at this stage to reduce or possibly stop further transmission of BTB.

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.

Molecular epidemiology of Mycobacterium tuberculosis complex strains isolated from livestock and wild animals in Italy suggests the need for a different eradication strategy for bovine tuberculosis

Bovine tuberculosis (bTB) is an important zoonosis, which has been re-emerging in different ecological scenarios. In Sicily, Italy, from 2004 to 2014, an anatomopathological survey for tuberculosis-like lesions both in farmed and wild animals was performed. The isolates were genotyped using spoligotyping and Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) techniques. High prevalence of lesions was observed for cattle (4%), pigs (4.9%) and wild boars (6.8%), and a total of 625 Mycobacterium bovis isolates were identified. Genotyping analysis showed the presence of 37 different spoligotypes including fifteen spoligotypes not present in other Italian regions and 266 MIRU-VNTR profiles. Spoligotype SB0120 exhibited the highest prevalence in cattle (50%) and pigs (56%) and the highest genetic variety with 126 different MIRU-VNTR profiles. The isolation of M. bovis in a farmer underlines the importance of M. bovis identification during the human TB diagnostic processes. This study supported the use of the genotyping analysis as a valuable tool for the evaluation of the epidemiological role of pigs and other domestic reservoirs such as goats and the role of wildlife in the maintenance of bTB infection.

Factors associated with tuberculosis treatment outcomes among tuberculosis patients attending tuberculosis treatment centres in 2016-2017 in Mogadishu, Somalia

Introduction

World Health Organization (WHO) reported that tuberculosis (TB) was a major health problem and the second leading cause of mortality globally. An estimated 1.8 million TB deaths were reported in 2015. In Somalia, the average TB incidence was 274 cases per 100,000 people in 2014; prevalence was 513 per 100,000 population; and mortality rate excluding human immune deficiency virus (HIV)/TB co-infection was 64/100,000. In addition, the prevalence rates of multi-drug resistant (MDR)-TB are still high, 5.2% among new cases and 40.7% for retreatment cases. The objective of this study was to determine individual and institutional level factors associated with TB treatment outcomes (TB-TOs) among patients attending TBTCs in Mogadishu.

Methods

The study design was cross-sectional, using quantitative and qualitative methods. Data was collected using interviewer administered semi-structured questionnaires and key in-depth interviews in 2016/2017. Qualitative data was coded using NVIVO8 and quantitative data analyzed using descriptive and inferential statistics at 95% confidence interval using SPSS20 software.

Results

The study used a sample of 385 TB patients. There were 315(81.8%) successful TB-TOs. Individual level factors-marital status, education level, HIV status, treatment category and knowledge on TB influenced TB-TOs (p-value < 0.05). Being married, educated, HIV-negative, new treatment case and knowledgeable on TB increased odds of successful TB-TOs (OR > 0, p value < 0.05) compared to other patients. TBTCs factors did not influence TB-TOs (p-value > 0.05).

Conclusion

TB-TOs were mainly affected by patient individual factors. There was need for patient education on TB management and treatment; and improved patient-health provider relationship.

Factors Affecting Herd Status for Bovine Tuberculosis in Dairy Cattle in Northern Thailand

The objective of this case-control study was to identify farm-level risk factors associated with bovine tuberculosis (bTB) in dairy cows in northern Thailand. Spatial analysis was performed to identify geographical clustering of case-farms located in Chiang Mai and Chiang Rai provinces in northern Thailand. To identify management factors affecting bTB status, a matched case-control study was conducted with 20 case-farms and 38 control-farms. Case-farms were dairy farms with at least single intradermal tuberculin test- (SIT-) reactor(s) in the farms during 2011 to 2015. Control-farms were dairy farms with no SIT-reactors in the same period and located within 5 km from case-farms. Questionnaires were administered for data collection with questions based on epidemiological plausibility and characteristics of the local livestock industry. Data were analyzed using multiple logistic regressions. A significant geographic cluster was identified only in Chiang Mai province (p < 0.05). The risk factor associated with presence of SIT-reactors in dairy herds located in this region was purchasing dairy cows from dealers (OR = 5.85, 95% CI = 1.66-20.58, and p = 0.006). From this study, it was concluded that geographic clustering was identified for dairy farms with SIT-reactors in these provinces, and the cattle movements through cattle dealers increased the risks for SIT-reactor farm status.

Prevalence of tuberculous lesion in cattle slaughtered in Mubende district, Uganda

BACKGROUND

The aim of this study was to estimate the prevalence of gross pathology suggestive of bovine tuberculosis (TB-like lesions) and evaluate animal's characteristics associated with the risk of having bovine TB-like lesions among cattle slaughtered in Mubende district in the Uganda cattle corridor.

METHOD

We conducted a cross sectional study in which 1,576 slaughtered cattle in Mubende district municipal abattoir underwent post-mortem inspection between August 2013 and January 2014. The presence of bovine TB-like lesions in addition to the animal's sex, age, breed, and sub-county of origin prior to slaughter were recorded. Associations between the presence of bovine TB-like lesions and animal's age, sex, breed, and sub-county of origin prior to slaughter were initially analysed using a univariable approach with the chi-square test, and subsequently with a multivariable logistic regression model to assess the combined impact of these animal characteristics with the risk of having a bovine TB-like lesion. Additionally, and as a secondary objective, tissue samples were collected from all carcases that had a bovine TB-like lesion and were processed using standard Mycobacterium culture and identification methods. The culture and acid fast positive samples were tested using Capilia TB-neo® assay to identify Mycobacterium tuberculosis complex (MTC).

RESULTS

Of 1,576 carcasses inspected, 9.7% (153/1,576) had bovine TB-like lesions from which Mycobacterium spp and Mycobacterium Tuberculosis Complex (MTC) were isolated in 13 (8.4%) and 12 (7.8%) respectively. Bovine TB-like lesions were more likely to be found in females (OR = 1.49, OR 95% CI: 1.06-2.13) and in older cattle (OR = 2.5, 95% CI: 1.64-3.7). When compared to Ankole cattle, Cross breed (OR = 6.5, OR 95% CI: 3.37-12.7) and Zebu cattle (OR = 2.57, 95% CI: 1.78-3.72) had higher odds of having bovine TB-like lesions. Animals from Kasanda (OR = 2.5, 95% CI: 1.52-4.17) were more likely to have bovine TB-like lesions than cattle from Kasambya.

CONCLUSIONS

The findings of study reveals that approximately one in ten slaughtered cattle presents with gross pathology suggestive of bovine TB in Mubende district in the Uganda cattle corridor district, however, we isolated MTC in only 8.4% of these bovine TB-like lesions. Therefore, there is a need to understand the cause of all the other bovine TB-like lesions in order to safe guard diagnostic integrity of meat inspection in Uganda.

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.

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.

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 diagnosis of bovine tuberculosis in bovine and human samples: implications for zoonosis

ABSTRACT 

Aim: To develop emerging diagnostic technique for bovine tuberculosis and to identify its potential risk factors. Materials & methods: Bacterial genomic DNA was isolated from bovine milk and human sputum samples and subjected to PCR using specific primer pairs. PCR results were validated using bacteriological cultures. Results: PCR amplification of the targeted DNA fragment of Mycobacterium bovis was successful in 12.33% (37/300) of the bovine samples. Interestingly, 500-bp DNA fragment was also amplified in 6.67% (6/90) of the sputum indicating the possibility of zoonotic transmission. Rearing of livestock in household, unpasteurized milk consumption and smoking were identified as potential risk factors. Conclusion: Results of the study may add value to bovine tuberculosis eradication campaigns to achieve the One Health initiative.

Brucellosis and bovine tuberculosis prevalence in livestock from pastoralist communities adjacent to Awash National Park, Ethiopia

This cross-sectional study investigated the prevalence of brucellosis and bovine tuberculosis (BTB) in local cattle and goat breeds of Oromo and Afar pastoralist communities living in two distinct parts around the Awash National Park. A questionnaire survey was carried out to assess information on husbandry, milk consumption habits, and on knowledge-attitude-practice regarding both diseases. Among a total of 771 animals from all sites tested by comparative intradermal tuberculin test (CIDT) none were BTB reactors with the >4mm cut-off. Using the >2mm cut-off, individual apparent prevalence was 0.9% (95%CI: 0.23-3.56%) in cattle and 0.7% (95%CI: 0.12-3.45%) in goats. Herd prevalence in Oromia and Afar sites was 0% and 66.7% respectively in goats and 16.7% and 50% in cattle. Among the 327 animals tested by enzyme linked immunoassay for brucellosis, 4.8% (95%CI: 1.2-17.1%) of cattle and 22.8% (95%CI: 5.98-29.5%) of goats were reactors. Highest individual prevalence of both diseases was found in Afar settlements with brucellosis being as high as 50%. Respondent ethnicity was the only risk factor for brucellosis positivity in goats in the univariable risk factor analysis. Knowledge about the diseases was poor. Raw goat milk was regularly consumed by women and children, putting them at risk for brucellosis. This study highlighted an increased prevalence gradient of BTB and brucellosis from West to East along the study sites with high brucellosis individual prevalence and abortion rates among Afar settlements in particular.

Prevalence of bovine tuberculosis and risk factor assessment in cattle in rural livestock areas of Govuro District in the Southeast of Mozambique

Background

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is an infectious disease of cattle that also affects other domestic animals, free-ranging and farmed wildlife, and also humans. In Mozambique, scattered surveys have reported a wide variation of bTB prevalence rates in cattle from different regions. Due to direct economic repercussions on livestock and indirect consequences for human health and wildlife, knowing the prevalence rates of the disease is essential to define an effective control strategy.

Methodology/Principal findings

A cross-sectional study was conducted in Govuro district to determine bTB prevalence in cattle and identify associated risk factors. A representative sample of the cattle population was defined, stratified by livestock areas (n = 14). A total of 1136 cattle from 289 farmers were tested using the single comparative intradermal tuberculin test. The overall apparent prevalence was estimated at 39.6% (95% CI 36.8–42.5) using a diagnostic threshold cut-off according to the World Organization for Animal Health. bTB reactors were found in 13 livestock areas, with prevalence rates ranging from 8.1 to 65.8%. Age was the main risk factor; animals older than 4 years were more likely to be positive reactors (OR = 3.2, 95% CI: 2.2–4.7). Landim local breed showed a lower prevalence than crossbred animals (Landim × Brahman) (OR = 0.6, 95% CI: 0.4–0.8).

Conclusions/Significance

The findings reveal an urgent need for intervention with effective, area-based, control measures in order to reduce bTB prevalence and prevent its spread to the human population. In addition to the high prevalence, population habits in Govuro, particularly the consumption of raw milk, clearly may potentiate the transmission to humans. Thus, further studies on human tuberculosis and the molecular characterization of the predominant strain lineages that cause bTB in cattle and humans are urgently required to evaluate the impact on human health in the region.

Tuberculosis prevalence and risk factors for water buffalo in Pará, Brazil

The prevalence of and possible risk factors for tuberculosis were studied in water buffalo from Pará, Brazil. In this study, 3,917 pregnant and nonpregnant female Murrah and Mediterranean buffaloes were studied; 2,089 originated from Marajó Island, and 1,108 were from the mainland. The comparative cervical tuberculin test was used as a diagnostic test for tuberculosis in these animals. The prevalence of positive buffaloes was 3.5 % (100/2,809) on Marajó Island and 7.2 % (80/1,108) on the mainland. The municipalities with the highest tuberculosis prevalence rates in animals were Ipixuna do Pará (10.1 %), Marapanim (9.8 %), Chaves (9.4 %), Paragominas (8.6 %), and Cachoeira do Arari (6.7 %). The tuberculosis prevalence was not significantly different between the Murrah (4.3 %) and Mediterranean (4.8 %) breeds or between pregnant (5 %) and nonpregnant (4.3 %) buffaloes. Tuberculosis was detected in water buffaloes from Pará, Brazil; the mainland buffalo exhibited the highest tuberculosis prevalence. These results indicate that this disease is dangerous to public health and buffalo farming in Pará.

Bovine tuberculosis and brucellosis prevalence in cattle from selected milk cooperatives in Arsi zone, Oromia region, Ethiopia

Background

Bovine tuberculosis (BTB) and bovine brucellosis are two important milk-borne zoonoses that have been shown to be prevalent to various degrees in Ethiopian cattle.

The study was carried out in four Woredas (districts) around Asella town, Arsi Zone between October 2011 and March 2012 and included 318 small-holders in 13 dairy cooperatives that marketed the delivered milk. The aims of the study were i) to assess the prevalence of the two diseases in cattle in a cross-sectional study, ii) to assess potential risk factors of BTB and brucellosis to humans as well as the knowledge-attitude-practice (KAP) among these farmers towards these diseases.

Results

BTB testing using the comparative intradermal skin test (CIDT) was done on 584 milking cows, out of which 417 were serologically tested for brucellosis using the Rose Bengal Plate Test and reactors confirmed with an indirect ELISA test (PrioCHECK®). The individual animal prevalence was 0.3% (95% CI 0.1% to 1.3%) for BTB, 1.7% (95% CI 0.8% to 3.5%) for brucellosis and 8.9% (95% CI 6.8% to 11.5%) for MAC (Mycobacterium avium complex). Of the 13 milk cooperatives, two had at least one positive BTB reactor and five had animals positive for brucellosis.

Cross-breeds accounted for 100% and 71.4% of the BTB and brucellosis reactors respectively. For both diseases, there were prevalence variations depending on Woreda. No animal was concomitant reactor for BTB and brucellosis.

Raw milk was consumed by 55.4% of the respondents. 79.2% of the respondents reported touching the afterbirth with bare hands. The latter was fed to dogs in 83% of the households. One cow among the herds of the 130 interviewees had aborted in the last 12 months. Among the interviewees, 77% stated knowing tuberculosis in general but 42 out of the 130 respondents (32.3%) did not know that BTB was transmitted by livestock. Less than half (47.7%) of the respondents knew about brucellosis.

Conclusions

Low prevalence of both diseases reflected the potential for the area to compete with the growing milk demand. The authors discussed the possible control strategies for the area.

Dilution effect in bovine tuberculosis: risk factors for regional disease occurrence in Africa

Changes in host diversity have been postulated to influence the risk of infectious diseases, including both dilution and amplification effects. The dilution effect refers to a negative relationship between biodiversity and disease risk, whereas the amplification effect occurs when biodiversity increases disease risk. We tested these effects with an influential disease, bovine tuberculosis (BTB), which is widespread in many countries, causing severe economic losses. Based on the BTB outbreak data in cattle from 2005 to 2010, we also tested, using generalized linear mixed models, which other factors were associated with the regional BTB presence in cattle in Africa. The interdependencies of predictors and their correlations with BTB presence were examined using path analysis. Our results suggested a dilution effect, where increased mammal species richness was associated with reduced probability of BTB presence after adjustment for cattle density. In addition, our results also suggested that areas with BTB infection in the preceding year, higher cattle density and larger percentage of area occupied by African buffalo were more likely to report BTB outbreaks. Climatic variables only indirectly influenced the risk of BTB presence through their effects on cattle density and wildlife distribution. Since most studies investigating the role of wildlife species on BTB transmission only involve single-species analysis, more efforts are needed to better understand the effect of the structure of wildlife communities on BTB dynamics.

A review of bovine tuberculosis at the wildlife-livestock-human interface in sub-Saharan Africa

Infection of wild animals by bovine tuberculosis (bTB) is raising concern worldwide. This article reviews the current epidemiological situation, risk of emergence and control options at the wildlife–livestock–human interface in sub-Saharan Africa. In livestock, bTB has been confirmed in the majority of countries from all parts of the continent. Wildlife infection is confirmed in seven countries from southern and eastern Africa, apparently spreading in the southern Africa region. Mycobacterium bovis has been isolated from 17 wild mammal species, although only four are suspected to play a role as maintenance host. Zoonotic risks are a concern, but no direct spillover from wildlife to humans has been documented, and no case of bTB spillback from wildlife to livestock has been confirmed. In this paper we assess the main risk factors of bTB spillover at the wildlife–livestock–human interface and suggest several research themes which could improve the control of the disease in the African context.

High prevalence of bovine tuberculosis in dairy cattle in central ethiopia: implications for the dairy industry and public health

Background

Ethiopia has the largest cattle population in Africa. The vast majority of the national herd is of indigenous zebu cattle maintained in rural areas under extensive husbandry systems. However, in response to the increasing demand for milk products and the Ethiopian government's efforts to improve productivity in the livestock sector, recent years have seen increased intensive husbandry settings holding exotic and cross breeds. This drive for increased productivity is however threatened by animal diseases that thrive under intensive settings, such as bovine tuberculosis (BTB), a disease that is already endemic in Ethiopia.

Methodology/Principal Findings

An extensive study was conducted to: estimate the prevalence of BTB in intensive dairy farms in central Ethiopia; identify associated risk factors; and characterize circulating strains of the causative agent, Mycobacterium bovis. The comparative intradermal tuberculin test (CIDT), questionnaire survey, post-mortem examination, bacteriology, and molecular typing were used to get a better understanding of the BTB prevalence among dairy farms in the study area. Based on the CIDT, our findings showed that around 30% of 2956 tested dairy cattle from 88 herds were positive for BTB while the herd prevalence was over 50%. Post-mortem examination revealed gross tuberculous lesions in 34/36 CIDT positive cattle and acid-fast bacilli were recovered from 31 animals. Molecular typing identified all isolates as M. bovis and further characterization by spoligotyping and MIRU-VNTR typing indicated low strain diversity within the study area.

Conclusions/Significance

This study showed an overall BTB herd prevalence of 50% in intensive dairy farms in Addis Ababa and surroundings, signalling an urgent need for intervention to control the disease and prevent zoonotic transmission of M. bovis to human populations consuming dairy products coming from these farms. It is suggested that government and policy makers should work together with stakeholders to design methods for the control of BTB in intensive farms in Ethiopia.

Bovine tuberculosis at a cattle-small ruminant-human interface in Meskan, Gurage region, Central Ethiopia

BACKGROUND

Bovine tuberculosis (BTB) is endemic in Ethiopian cattle. The aim of this study was to assess BTB prevalence at an intensive contact interface in Meskan Woreda (district) in cattle, small ruminants and suspected TB-lymphadenitis (TBLN) human patients.

METHODS

The comparative intradermal test (CIDT) was carried out for all animals involved in the cross-sectional study and results interpreted using a > 4 mm and a > 2 mm cut-off. One PPD positive goat was slaughtered and lymph nodes subjected to culture and molecular typing. In the same villages, people with lymphadenitis were subjected to clinical examination. Fine needle aspirates (FNA) were taken from suspected TBLN and analyzed by smear microscopy and molecular typing.

RESULTS

A total of 1214 cattle and 406 small ruminants were tested for BTB. In cattle, overall individual prevalence (> 2 mm cut-off) was 6.8% (CI: 5.4-8.5%) with 100% herd prevalence. Only three small ruminants (2 sheep and 1 goat) were reactors. The overall individual prevalence in small ruminants (> 2 mm cut-off) was 0.4% (CI: 0.03-5.1%) with 25% herd prevalence. Cattle from owners with PPD positive small ruminants were all PPD negative. 83% of the owners kept their sheep and goats inside their house at night and 5% drank regularly goat milk.FNAs were taken from 33 TBLN suspected cases out of a total of 127 screened individuals with lymph node swellings. Based on cytology results, 12 were confirmed TBLN cases. Nine out of 33 cultures were AFB positive. Culture positive samples were subjected to molecular typing and they all yielded M. tuberculosis. M. tuberculosis was also isolated from the goat that was slaughtered.

CONCLUSIONS

This study highlighted a low BTB prevalence in sheep and goats despite intensive contact with cattle reactors. TBLN in humans was caused entirely by M. tuberculosis, the human pathogen. M. tuberculosis seems to circulate also in livestock but their role at the interface is unknown.

Bovine tuberculosis prevalence survey on cattle in the rural livestock system of Torodi (Niger)

BACKGROUND

Bovine tuberculosis (BTB) is a widespread zoonosis in developing countries but has received little attention in sub-Saharan Africa, especially in Niger. Recent investigations confirmed the high incidence of the disease in cattle slaughtered in an abattoir in Niamey. The fact that most of the animals in which M. bovis has been identified were from the rural area of Torodi implied the existence of a probable source of BTB in this region. This study aimed to determine the prevalence of BTB infection in cattle and to identify risk factors for infection in human and cattle populations in Torodi.

METHODS AND PRINCIPAL FINDINGS

A survey was carried out at the level of households keeping livestock (n = 51). The questionnaire was related to the potential risk factors and the presence of clinical signs of TB both in animals and humans. Comparative Intradermal Tuberculin Test was conducted to determine the TB status in cattle (n = 393). The overall apparent individual animal prevalence of tuberculin reactors was 3.6% (CI: 95%, 1.9-5.9), whereas the individual true prevalence was estimated at 0.8% (CI: 95%, 0.0-5.0). Using a multivariate logistic regression analysis and a classification tree analysis, the only household level risk factor that significantly influenced the presence of BTB in cattle was the presence of animals coughing in the herd (OR = 4.7, 95% CI: 1.12-19.71, p-value = 0.034). The lack of the practice of quarantine was borderline significant (OR = 4.2, 95% CI: 0.96-18.40, p-value = 0.056).

CONCLUSION/SIGNIFICANCE

The study confirmed that BTB is endemic in cattle in Torodi and the risk of the transmission of the disease to humans is potentially high. For the control of the disease in livestock, slaughtering of infected animals and the compensation of the owners is needed. Collaboration between the veterinary and the medical sectors, in the diagnosis, monitoring, prevention and control of BTB is strongly encouraged.

Prevalence of bovine tuberculosis in pastoral cattle herds in the Oromia region, southern Ethiopia

A cross-sectional study of bovine tuberculosis (BTB) was conducted in pastoral cattle herds in southern Ethiopia, from February to August 2008 using the comparative intradermal tuberculin test. The prevalence of BTB and the risk factors for having positive reactor herds were assessed in four pastoral associations in two districts of southern Ethiopia, namely Goro-Dola with 242 cattle in 16 herds and Liben with 231 cattle in 15 herds. A herd was considered positive if there was at least one reactor animal in a herd. The test results were interpreted based on the Office Internationale des Epizooties recommended 4-mm and a recently suggested 2-mm cut-off. The apparent individual animal prevalence of tuberculin reactors was 5.5% (95% confidence interval (CI), 4.0-8.0%) and 7.0% (95% CI, 5.0-10.0%), whereas the true prevalence estimate was 4.4% (95% CI, 0.8-8.0%) and 6.1% (95% CI, 2.6-9.5%), when using the 4-mm and the 2-mm cut-offs, respectively. The overall herd apparent prevalence of tuberculin reactor animals was 41.9% (95% CI, 24.9-60.9%) and 48.4% (95% CI, 30.2-66.9%) with the 4-mm and 2-mm cut-offs, respectively. A positive tuberculin test was associated with the age of animals and the main drinking water sources during dry seasons. In order to investigate the public health risks and the epidemiological importance of BTB in the area, we recommend to include other livestock species (camels and goats) as well as humans in future studies.

Repeated cross-sectional skin testing for bovine tuberculosis in cattle kept in a traditional husbandry system in Ethiopia

Representative repeated cross-sectional skin testing for bovine tuberculosis (TB) was conducted over a period of three years in a total of 5377 cattle in three randomly selected woredas (districts) in Ethiopia (Meskan, Woldia and Bako-Gazer) that had never previously been tested for TB. Almost all (99 per cent) of the animals included local zebus kept in traditional husbandry systems. The comparative intradermal tuberculin test with two diagnostic thresholds were used to define positive test results, one according to the World Organisation for Animal Health (OIE) recommended cut-off of more than 4 mm, and the other with a cut-off of >2 mm. Data analysis was performed using a logistic regression model with a random effect at the village level. Applying the OIE definition, the overall representative apparent prevalence of bovine TB in skin test-positive local zebus was 0.9 per cent (95 per cent confidence interval [CI] 0.6 to 1.3 per cent). Using a cut-off of more than 2 mm the overall representative prevalence increased to 4 per cent (95 per cent CI 2.4 to 4.8 per cent). Due to the low apparent prevalence, the true prevalence could be calculated only in Meskan (4.5 per cent) and Bako-Gazer (2.4 per cent) for the more than 2 mm cut-off. With the exception of Meskan, prevalence by woreda did not change significantly over the years. Mycobacterium avium reactor animals were found at all study sites, but there were significant geographical variations. Overall, bulls and oxen were more at risk of being positive reactors (odds ratio [OR] 1.6, 95 per cent CI 1.1 to 2.3; OR 2, 95 per cent CI 1.4 to 2.6, respectively), as were animals in good body condition (OR 2, 95 per cent CI 1.5 to 2.9). Similar results were found at woreda level with the exception of Woldia, where none of the analysed variables was significantly associated with a positive test result.

Risk factors associated with the presence of positive reactions in the SCCIT test in water buffalo around two cities in Punjab, Pakistan

The present study was undertaken to find out the association of certain risk factors with the positive SCCIT (single comparative cervical intradermal tuberculin) test in water buffaloes at Faisalabad and Okara, Pakistan. Seventy-six herds (697 buffaloes) at Faisalabad and 56 (395 buffaloes) at Okara were included in the study. The buffaloes were screened through SCCIT Test. Positive reaction to SCCIT test was recorded in 14% of herds and in 3% of buffaloes. The herds positive for this test were 18% when herds with less than 10 animals were excluded from the analysis and these were 19% when herds with less than 10 buffaloes were excluded. The results of logistic analysis (crude and adjusted) revealed the association of lactating status of buffaloes (OR=1.8) and the presence of cattle at the farm (OR=2-4) with positive SCCIT test. After controlling for the farm, the risk of a positive skin test was 1.5 times higher if we change the location of the animal. Similarly, the controlled analysis (for the farm, breed and other variables) revealed an increased risk (OR=1.1) of a positive skin test with the increase in cattle at the farm. The breed controlled stratified analysis showed the association of a number of cattle at the farm with a positive skin test. It can be concluded from the study that the prevalence of tuberculosis on the basis of a positive skin test is higher at herd level and lower at animal level. Further the risk of a positive skin test is higher when cattle are present at the farm.

Bovine tuberculosis at the wildlife-livestock-human interface in Hamer Woreda, South Omo, Southern Ethiopia

Bovine tuberculosis (BTB) is endemic in cattle in the Ethiopian Highlands but no studies have been done so far in pastoralists in South Omo. This study assessed the prevalence of bovine tuberculosis (BTB) at an intensive interface of livestock, wildlife and pastoralists in Hamer Woreda (South Omo), Ethiopia. A cross-sectional survey including a comparative intradermal skin testing (CIDT) was conducted in 499 zebu cattle and 186 goats in 12 settlements. Sputum samples from 26 symptomatic livestock owners were cultured for TB. Fifty-one wildlife samples from 13 different species were also collected in the same area and tested with serological (lateral flow assay) and bacteriological (culture of lymph nodes) techniques. Individual BTB prevalence in cattle was 0.8% (CI: 0.3%–2%) with the >4 mm cut-off and 3.4% (CI: 2.1%–5.4%) with the >2 mm cut-off. Herd prevalence was 33.3% and 83% when using the >4 and the >2 mm cut-off respectively. There was no correlation between age, sex, body condition and positive reactors upon univariate analysis. None of the goats were reactors for BTB. Acid fast bacilli (AFB) were detected in 50% of the wildlife cultures, 79.2% of which were identified as Mycobacterium terrae complex. No M. bovis was detected. Twenty-seven percent of tested wildlife were sero-positive. Four sputum cultures (15.4%) yielded AFB positive colonies among which one was M. tuberculosis and 3 non-tuberculous mycobacteria (NTM). The prevalence of M. avium-complex (MAC) was 4.2% in wildlife, 2.5% in cattle and 0.5% in goats. In conclusion, individual BTB prevalence was low, but herd prevalence high in cattle and BTB was not detected in goats, wildlife and humans despite an intensive contact interface. On the contrary, NTMs were highly prevalent and some Mycobacterium spp were more prevalent in specific species. The role of NTMs in livestock and co-infection with BTB need further research.

Risk factors associated with observed clinical lumpy skin disease in Ethiopia

A cross-sectional study based on a questionnaire survey was conducted to determine the distribution of lumpy skin disease (LSD) and associated risk factors in three main agro-climatic zones of Ethiopia. A total of 330 questionnaire surveys were collected from 44 peasant associations (PA) distributed in 15 districts. Across agro-climate zones, herd-level LSD prevalence in the midland agro-climate was significantly higher 55.2% [95% confidence interval (CI) 47.5-62.6] than in highland and lowland agro-climate zones. Overall observed LSD prevalence at animal-level was 8.1% (95% CI 7.3-8.9) and observed mortality was 2.12% (95% CI 1.73-2.6). The odds ratio (OR) of LSD occurrence in midland vs. highland and lowland vs. highland zones was 3.86 (95% CI 2.61-5.11) and 4.85 (95% CI 2.59-7.1), respectively. Significantly high risk of LSD occurrence was associated with communal grazing and watering management (OR 4.1, 95% CI 2.02-6.18) and introduction of new cattle (OR 8.5, 95% CI 6.0-11.0). Our findings describe the distribution of LSD in different agro-climates in Ethiopia along with associated risk factors, and can help shed light on the epidemiology of LSD in other African countries suffering from the disease.