Laboratory diagnostic methods and reported outbreaks of anthrax in Ethiopia

Anthrax is a zoonotic disease caused by Bacillus anthracis, a Gram-positive, non-motile, spore-forming bacterium. It is a globally distributed disease, having been reported from all continents that are populated heavily with animals and humans. The objectives were to review general laboratory diagnostic testing methods and reported outbreaks of anthrax in Ethiopia. Anthrax was second top zoonotic priority next to rabies and endemic in Ethiopia that may occur in May and June every year (Anthrax season) in several farming localities. Animal hosts acquire the disease through grazing, usually by ingestion or inhalation while there are three major routs of transmission: ingestion, inhalation and cutaneous. This review indicated that anthrax remains to be major public and animal health problem in Ethiopia. Although suspected cases of anthrax are reported from several districts, they are not well confirmed by laboratories. Prevention and control of anthrax in animals effectively reduces its impact on public health and the national economy. The control of anthrax outbreaks among domestic animals is primarily dependent on rapid identification and treatment of affected animals; enhanced surveillance for additional cases; implementation of control measures including quarantine, prophylaxis, vaccination and the proper disposal of dead animals with decontamination is critical. DOI: http://dx.doi.org/10.5281/zenodo.377389

Genotype Diversity of Mycobacterium bovis and Pathology of Bovine Tuberculosis in Selected Emerging Dairy Regions of Ethiopia

Bovine tuberculosis (bTB) is endemic in Ethiopia with higher prevalence in cattle, particularly in the central parts. Spread of Mycobacterium bovis (M. bovis) to wider regions is inevitable in uncontrolled conditions. This study was conducted to explore the pathology, characterize M. bovis strains, and describe genotypic diversity to demonstrate possible epidemiological links in emerging dairy areas of Ethiopia, namely, Mekelle and Gondar. Twenty-seven bTB positive cattle identified by the Single Intradermal Comparative Cervical Tuberculin (SICCT) test were subjected to post-mortem inspection to determine lesion distribution and pathological score. Samples from tissues with visible tuberculous or suspected non-visible lesions were processed and cultured following a standard protocol. Isolates identified as M. bovis by Region of Difference (RD)-based Polymerase Chain Reaction (PCR) were also spoligotyped to determine their spoligotype patterns. Post-mortem inspection of visceral organs indicated bTB suggestive lesions in 41% of the animals, with 25% being in the lungs. Lymph nodes from 77% of the animals had lesions. Fifty-five isolates identified from 24 of the slaughtered animals were confirmed as M. bovis. No other mycobacterial species were isolated. Spoligotyping classified strains from 21 of these animals into seven spoligotype patterns: SB0133, SB0134, SB1176, SB2233, SB2290, SB2467, and SB2520. More than one spoligotype were identified from five of these animals, and none of the last four spoligotypes had been reported in Ethiopia before. SB0134 was the most predominant type (47%) followed by SB0133 (25.5%). SB0133, SB2290, SB2467, and SB1176 are spoligotypes lacking spacers 3–7, characteristics of M. bovis strains of the African 2 (Af2) clonal complex, while SB0134, SB2233, and SB2520 do not belong to any of the established clonal complexes and likely to have a different evolutionary history. Despite a small sample size, the present study showed strain diversity with multiple genotypes identified in a single herd and even within a single animal, and the genotypes showed no sign of geographical localization, which could be a consequence of significant movement of bTB diseased cattle around the country, spreading the disease. Therefore, any future control programme of bTB in Ethiopia needs to address the risks of cattle movement

Population structure and transmission of Mycobacterium bovis in Ethiopia

Bovine tuberculosis (bTB) is endemic in cattle in Ethiopia, a country that hosts the largest national cattle herd in Africa. The intensive dairy sector, most of which is peri-urban, has the highest prevalence of disease. Previous studies in Ethiopia have demonstrated that the main cause is Mycobacterium bovis , which has been investigated using conventional molecular tools including deletion typing, spoligotyping and Mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR). Here we use whole-genome sequencing to examine the population structure of M. bovis in Ethiopia. A total of 134 M . bovis isolates were sequenced including 128 genomes from 85 mainly dairy cattle and six genomes isolated from humans, originating from 12 study sites across Ethiopia. These genomes provided a good representation of the previously described population structure of M. bovis , based on spoligotyping and demonstrated that the population is dominated by the clonal complexes African 2 (Af2) and European 3 (Eu3). A range of within-host diversity was observed amongst the isolates and evidence was found for both short- and long-distance transmission. Detailed analysis of available genomes from the Eu3 clonal complex combined with previously published genomes revealed two distinct introductions of this clonal complex into Ethiopia between 1950 and 1987, likely from Europe. This work is important to help better understand bTB transmission in cattle in Ethiopia and can potentially inform national strategies for bTB control in Ethiopia and beyond

Laboratory diagnostic methods and reported outbreaks of anthrax in Ethiopia

Anthrax is a zoonotic disease caused by Bacillus anthracis, a Gram-positive, non-motile, spore-forming bacterium. It is a globally distributed disease, having been reported from all continents that are populated heavily with animals and humans. The objectives were to review general laboratory diagnostic testing methods and reported outbreaks of anthrax in Ethiopia. Anthrax was second top zoonotic priority next to rabies and endemic in Ethiopia that may occur in May and June every year (Anthrax season) in several farming localities. Animal hosts acquire the disease through grazing, usually by ingestion or inhalation while there are three major routs of transmission: ingestion, inhalation and cutaneous. This review indicated that anthrax remains to be major public and animal health problem in Ethiopia. Although suspected cases of anthrax are reported from several districts, they are not well confirmed by laboratories. Prevention and control of anthrax in animals effectively reduces its impact on public health and the national economy. The control of anthrax outbreaks among domestic animals is primarily dependent on rapid identification and treatment of affected animals; enhanced surveillance for additional cases; implementation of control measures including quarantine, prophylaxis, vaccination and the proper disposal of dead animals with decontamination is critical. DOI: http://dx.doi.org/10.5281/zenodo.377389

BCG vaccination reduces bovine tuberculosis transmission, improving prospects for elimination.

Bacillus Calmette-Guérin (BCG) is a routinely used vaccine for protecting children against Mycobacterium tuberculosis that comprises attenuated Mycobacterium bovis. BCG can also be used to protect livestock against M. bovis; however, its effectiveness has not been quantified for this use. We performed a natural transmission experiment to directly estimate the rate of transmission to and from vaccinated and unvaccinated calves over a 1-year exposure period. The results show a higher indirect efficacy of BCG to reduce transmission from vaccinated animals that subsequently become infected [74%; 95% credible interval (CrI): 46 to 98%] compared with direct protection against infection (58%; 95% CrI: 34 to 73%) and an estimated total efficacy of 89% (95% CrI: 74 to 96%). A mechanistic transmission model of bovine tuberculosis (bTB) spread within the Ethiopian dairy sector was developed and showed how the prospects for elimination may be enabled by routine BCG vaccination of cattle.Bill & Melinda Gates Foundation (in partnership with the U.K. Department for International Development.) OPP1176950 Biotechnology and Biological Sciences Research Council, the Department for International Development, the Economic & Social Research Council, the Medical Research Council, the Natural Environment Research Council and the Defence Science & Technology Laboratory, under the Zoonoses and Emerging Livestock Systems (ZELS) programme. BB/L018977/1 and Biotechnology and Biological Sciences Research Council (BB/M011194/1 to KW