Abattoir-based study on the epidemiology of caprine tuberculosis in Ethiopia using conventional and molecular tools

Mycobacterium tuberculosis complex in domestic goats in Southern Spain

Tuberculosis (TB) is a zoonotic infectious disease caused by bacteria belonging to the Mycobacterium tuberculosis complex (MTC), which can affect a wide variety of domestic and wild animal species. Although the role of goats as a reservoir of MTC bacteria has been evidenced, information about the circulation of MTC strains in this species is still very scarce. The aim of the present study was to determine the seroprevalence, spatial distribution, risk factors and MTC spoligotypes circulating in goats from Andalusia (Southern Spain), the Spanish region with the largest goat census and a hotspot area of TB in both cattle and wild ungulates. A total of 2155 serum samples from 80 goat flocks were analyzed by an in-house ELISA using the P22 protein complex as a coating antigen. Antibodies against MTC were detected in 473 goats (21.9%, 95% CI: 20.2-23.7) and the true seroprevalence was 22.3% (95% CI: 20.6-24.1). Seropositivity was found in 72 (90.0%) of the 80 flocks analyzed. The generalized estimating equation model showed that the management system (higher seroprevalence on intensive and semi-intensive farms), and the presence of hospital pens inside the regular stables, were risk factors potentially associated with MTC exposure in goats in Southern Spain. The spatial analysis identified a significant spatial cluster (p < 0.001) in Eastern Andalusia. A total of 16 different MTC spoligotypes, including five of M. caprae and eleven of M. bovis, were identified in goats between 2015 and 2022 in the study area, with SB0157 as the most frequently isolated. The results obtained indicate widespread and non-homogeneous spatial distribution of MTC in goat herds from Southern Spain. The high individual and herd-level seroprevalence values found suggest that goats could play a significant role in the maintenance and transmission of MTC in the study area. Our results highlight the importance of implementing control measures in this species.

Pathological study and molecular detection of zoonotic diseases in small ruminants at slaughter houses in Mymensingh, Bangladesh

Background and Aim:

Slaughterhouses act as a significant public health hotspot in developing countries like Bangladesh. The study aimed to investigate small ruminants at slaughterhouses for pathological study and molecular detection of important zoonotic diseases.

Materials and Methods:

A total of 75 goats and 14 sheep were investigated from June 2019 to January 2020 at different slaughterhouses in Mymensingh division, Bangladesh. The targeted diseases were tuberculosis (TB), listeriosis, Q fever, brucellosis, anthrax, toxoplasmosis, hydatidosis, and linguatulosis. The tentative diagnosis was made based on gross and histopathological lesions. Polymerase chain reaction (PCR) was performed to confirm the causal agents of zoonotic diseases using disease-specific primers.

Results:

Grossly, caseous nodule formation in the visceral organs; enlarged and calcifications of mesenteric lymph nodes (MLNs); hydatid cyst formation in the liver were the predominant lesions observed. Histopathologically, granuloma, caseous necrosis, and calcifications admixed with acid-fast bacteria in the MLNs, liver, spleen, and kidney were seen as suggestive of infectivity due to TB. Septic lymphadenitis mixed with rod-shaped bacteria, doughnut granuloma, fibroplasia accompanied by eosinophils and lymphocytic infiltration in MLNs, and portal granuloma were observed in listeriosis, Q fever, linguatulosis, and toxoplasmosis suspected cases, respectively. The PCR amplified Mycobacterium tuberculosis complex (372 bp), Mycobacterium bovis (600 bp), Listeria monocytogenes (517 bp), Toxoplasma gondii (512 bp), and Coxiella burnetii (687 bp) species-specific amplicons. In addition, linguatulosis and hydatidosis were identified in six and three goats, respectively. Brucellosis and anthrax were not detected in any cases. The slaughterhouse samples were also found to harbor the coexistence of different zoonotic pathogens.

Conclusion:

Deadly infectious zoonotic diseases in goats and sheep at slaughterhouses may cause widespread public health risks. As a result, more intensive monitoring and epidemiological surveys are required to successfully prevent and control zoonotic diseases.

Pathology of Bovine Tuberculosis in Three Breeds of Dairy Cattle and Spoligotyping of the Causative Mycobacteria in Ethiopia

Different breeds of cattle were observed to have a variable degree of susceptibility to bovine tuberculosis (bTB). The screening of bTB was conducted on 720 dairy cattle consisting of three breeds using the single intradermal cervical comparative tuberculin (SICCT) test. Besides this, 43 SICCT test-positive cattle were used to compare the severity of the pathology of bTB among the three breeds and to identify the causative mycobacteria using spoligotyping. The overall SICCT test positivity was 17.92% (129/720) by pooling all animals in the three farms. There was a significant difference in SICCT test positivity among the three breeds (χ2 = 71.06; p < 0.001); the highest (25.34%) was recorded in the crossbreed followed by the Boran breed (10.08%), while the least (3.14%) was recorded in the Jersey breed. On other hand, the highest median pathology score (10.0, interquartile range, IQR = 6.0-17.0) was recorded in Boran followed by cross (5.0, IQR = 3.5-7.5), while the least (3.0, IQR = 2.25-3.0) was recorded in Jersey. Thus, the difference in the median pathology scores was significant [Kruskal Wallisχ ( 2 ) 2 = 18.78, p < 0.001] among the three breeds. Furthermore, multivariate analysis using ordinal logistic regression by considering age, sex, breed, reproductive status, and location of the farms also showed a significant [χ ( 2 ) 2 = 11.97, p < 0.01] difference in pathology scores among the three breeds of cattle. Even at a single-herd level at Holeta, the difference in severity of pathology between the Boran and crossbreeds was significant (U = 33.5; p < 0.01). Culture positivity was 39% in 108 suspicious tissues. Fourteen Mycobacterium bovis (M. bovis) and two Mycobacterium tuberculosis (M. tuberculosis) were isolated from the lesions. All the 14 M. bovis isolates belonged to SB0912, while the two M. tuberculosis belonged to SIT54. In conclusion, although the frequency of the SICCT test positivity was high in the crossbreed, a more severe pathology was observed on the Boran (zebu) breed. In addition M. tuberculosis was isolated from TB lesions of dairy cattle, demonstrating the role of M. tuberculosis in causing TB in cattle.

Tuberculosis in small ruminants and dromedary camels in Ethiopia: A systematic review and meta-analysis

Tuberculosis (TB) is a chronic infectious disease of livestock with serious economic and public health impact in Ethiopia. The disease is reported from cattle, small ruminants and dromedary camels in the country. However, there is no organized summary report on the magnitude and distribution pattern of TB in small ruminants and dromedary camels, unlike that of bovine TB. Consequent to this gap, this review was organized to provide pooled prevalence estimates, and examine level of heterogeneity among studies at national level. In addition, it attempts to illustrate the spatial distribution patterns along the three livestock species based on available reports. Tuberculosis articles on the aforesaid livestock species were searched online using PubMed, CAB direct, Web of Science and AJOL databases. Eighteen articles published from January 2000 to May 15, 2020, written in the English language that fulfill the selection quality criteria were considered for the review. Altogether, 50 district based observational studies conducted on 10,371 goats, 6262 dromedary camels, and 1457 sheep were used for analysis. Accordingly, the pooled prevalence estimates of TB, in a random effect model were 2.3 % (95 % CI: 1.7, 3.1) for goats, 0.8 % (95 % CI: 0.5, 1.4) for sheep and 8.2 % (95 % CI: 6.6, 10.2) for dromedary camels. The subgroup analysis revealed presence of statistically significant differences (p < 0.001) in pooled prevalence estimates among the three species. In multivariable meta-regression model, diagnostic methods used for screening (single intra-dermal comparative cervical tuberculin test (SICCTT)> 2mm, SICCTT > 4mm and detailed postmortem inspection) were the only predictors identified to show statistically significant difference (p<0.001) and explained 68.6 % of the explainable heterogeneity (R² =0.686) in goat TB studies. In general, study reports on small ruminant and dromedary camel TB are limited throughout the country. The most significant data gaps were in Gambella, and Benshangul-Gumuz regional states, where no single report could be retrieved on small ruminant TB. Limitation of study reports and lack of comparable categories constrained further investigation on other predictors in sheep and camel studies. Thus, the authors would like to emphasize the need for more representative studies in the species of concern in all regions of the country. Meanwhile, the relatively higher proportion of TB in dromedary camels demands special attention in arid and semiarid parts of the country, as it is the leading livestock species on which agropastoralist and pastoralists livelihoods depend.

Review on Epidemiology and Public Health Importance of Goat Tuberculosis in Ethiopia

Small ruminant is an important and integral part of livestock in Ethiopia. Especially, goats are attractive to people of Ethiopia because of the ability to resist challenges, easily adapt to different ecological regions, and need small land to rearing and small initial capital in which poor people can engaged in the production system. In spite of the presence of large number of goat population in Ethiopia, it fails to utilize expected productivity due to many factors. Among the factors, which limit the economic returns of goats, diseases stand frontline. Tuberculosis is one the diseases that affect goats' health and production in Ethiopia. Goat tuberculosis is a chronic disease, which is characterized by the development of granulomas, essentially in the respiratory tract and related lymph nodes, from which the mycobacteria are discharged and contaminate other susceptible animals. Goat tuberculosis has a public health implication in Ethiopia because of the farmers' habit of consuming raw goat milk and its products, and they do have consistent or day-to-day contact with their goats. The etiological agents also transmitted to humans through the aerogenous route from those animals with active cases in the herd. The infection has been reported from several parts of different areas of the country dependent on the abattoir inspections. Therefore, attention should be given towards the control of tuberculosis in livestock; public health education on zoonotic importance of the disease or awareness creation and the national tuberculosis control needs to consider the one health approach, and further epidemiological studies should be undertaken.

Tuberculosis Caused by Mycobacterium bovis in a Sheep Flock Colocated with a Tuberculous Dairy Cattle Herd in Central Ethiopia

Mycobacterium bovis (M. bovis) has an exceptionally wide host range including sheep. Information on tuberculosis (TB) in sheep is scarce, and there appears to be conflicting opinions about the relative susceptibility of sheep to infection. In Ethiopia, there was no single previous report on tuberculosis in sheep, though mixed farming of cattle and sheep is a common practice. In this study, following the observation of TB-like lesions on sheep died from sheep flock kept in contact with cattle herd, further investigation was conducted on the flock to assess the magnitude of the infection and identify and characterize the causative M. bovis strain. An outbreak investigation was carried out on 26 eligible sheep out of 33 sheep found on the farm. Comparative intradermal tuberculin (CIDT) test, postmortem examination, Mycobacterium culturing, and spoligotyping were the techniques used in the study. The prevalence of TB in the tested sheep was 15% (4/26). All the sheep that were positive to CIDT had gross lesions suggestive of TB. Three of the positive sheep had extensive and multiple lesions. M. bovis was isolated from all four sheep and the strain was identified as spoligotype SBO134. The in-contact dairy cows were screened for TB and 98% (45/46) of the cows tested positive to CIDT. Furthermore, the same strain, SB0134, was also isolated from the two in-contact cows. The isolation of a matching genotype (SB0134) of M. bovis from both species sharing a known epidemiologic link strongly suggests that the sheep flock might have acquired the pathogen from the dairy cows. This warrants strict physical separation of the sheep flock from the cattle herd to prevent such interspecies transmission of M. bovis.

Epidemiology of Mycobacterium bovis and Mycobacterium tuberculosis in animals: Transmission dynamics and control challenges of zoonotic TB in Ethiopia

Mycobacterium tuberculosis complex is the cause of tuberculosis (TB) in humans and other animals. Specifically, Mycobacterium bovis (M. bovis) and Mycobacterium tuberculosis (M. tuberculosis) are highly pathogenic mycobacteria that may infect different animal species and are the sources of TB in humans. The objective of this paper was to review the epidemiology of M. bovis and M. tuberculosis in animals. The review also highlighted the transmission dynamics of M. bovis and M. tuberculosis in humans and animals and control challenges of zoonotic TB in Ethiopia. The literature review focused on scientific peer-reviewed articles from studies exclusively conducted in Ethiopia that were published from 1998 to 2017. Husbandry system, breed and herd size have significant role in the epidemiology of bovine tuberculosis (BTB) in Ethiopia. The information presented reveals that different strains of M. bovis are widely distributed in domestic animals predominantly in the Ethiopian cattle and the main strain was found to be SB1176. In addition, the isolation of M. tuberculosis from domestic animals in different settings signifies the circulation of the agent between humans and animals in Ethiopia. The life styles of the Ethiopian communities, close contact with domestic animals and/or the habit of consuming raw animal products, are suggested as the main factors for transmission of M. bovis and M. tuberculosis between human and animal which may have impact on the TB control program in human. In Ethiopia, a human TB control program has been widely implemented, however, the role of animal in the transmission of the causative agent has been neglected which could be one of the challenges for an effective control program. This warrants the need for incorporating animal TB control programs using "One Health" approach for effective TB control for both human and animal.

Prevalence of bovine and avian tuberculosis in camel herds and associated public health risk factors in Isiolo County, Kenya

A cross-sectional study was conducted among 308 lactating camels selected from 15 herds from three different camel milk clusters in Isiolo County, Kenya, to determine prevalence of bovine and avian tuberculosis using Single Comparative Intradermal Tuberculin Skin test. Seventy-five (75) questionnaires were administered to pastoralists/herders, and focus group discussions were conducted among 3-5 pastoralists/herders selected from each camel herd to collect information on camel husbandry and health management practices and knowledge on tuberculosis in livestock and wildlife. An overall prevalence of bovine and avian reactors was 3.57 and 18.18%, respectively, with bovine and avian reactors for different clusters being 2.38, 3.82, and 4.48% and 25, 17.2, and 11.94%, respectively. There was significant difference (p < 0.05) in prevalence of bovine and avian reactors between different clusters. There was a negative correction (r = -0.1399) between herd size and bovine reactors, while there was a positive correlation (r = 0.0445) between herd size and avian reactors. The respondents indicated that camel herds are exposed to several risk factors like close contact with other herds or livestock or wildlife during grazing and at watering points. Pastoralists have poor knowledge on mode of infection and transmission of bovine or avian tuberculosis. The high prevalence of bovine and avian reactors and pastoralists' poor knowledge on mode of transmission signify potential risk to public health.

An assessment of caprine tuberculosis prevalence in Lubumbashi slaughterhouse, Democratic Republic of Congo

Caprine tuberculosis is a major health problem for goats and a major zoonosis of veterinary public health interest. In order to prepare a response to and control of caprine tuberculosis, to evaluate the potential risks to public health, and to assess the prevalence of the disease in Katanga province, Democratic Republic of Congo, 656 goats that were slaughtered at the Kabasele abattoir of Mzee Laurent-Desire Kabila Market in Lubumbashi were subjected to rigorous veterinary inspection during June to August 2012. All goat specimens came from the Kasumbalesa, Kasenga, and Kipushi areas of Katanga province. Consequently, suspected organs presenting signs of tuberculosis were collected and examined using Ziehl-Neelsen stains for diagnosis. Through this investigative inspection in the province, we found an overall prevalence of caprine tuberculosis of 1.68%. Although females showed higher prevalence of caprine tuberculosis (1.07%) compared to males (0.61%), and adults showed higher prevalence (1.22%) than juveniles (0.45%), these comparisons were not statically significant. However, lung and intestine infection by tuberculosis showed significantly higher prevalence of positive cases (1.21 and 0.46%, respectively) (p < 0.05). Goats from Kasumbalesa had the highest prevalence of caprine tuberculosis (1.22%) compared to goats from Kipushi (0.31%) and Kasenga (0.18%). These findings show the risk of caprine tuberculosis in the province for the first time, and we therefore recommend the implementation of strict animal biosecurity and tuberculosis controlling protocols.