Practical and effective diagnosis of animal anthrax in endemic low-resource settings

Aminu, Olubunmi Rhoda; Lembo, Tiziana; Zadoks, Ruth N.; Biek, Roman; Lewis, Suzanna; Kiwelu, Ireen; Mmbaga, Blandina T; Mshanga, Deogratius; Shirima, Gabriel; Denwood, Matt; Forde, Taya

doi:10.1371/journal.pntd.0008655

Cited by 21 publications

(25 citation statements)

References 33 publications

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“…However, in our study, spleen samples were clearly superior to blood and intestinal samples collected postmortem . On the other hand, the non-invasively collected ear clipping sample performed well with real-time PCR, like the skin samples showing high sensitivity and specificity in a previous study [ 15 ]. Because anthrax is a fatal disease with a high mortality rate in humans and animals if not diagnosed and treated in time, rapid and reliable diagnosis is of utmost importance.…”

Section: Discussionmentioning

confidence: 70%

“…In countries with regular anthrax cases, outbreaks may occur in very remote or challenging environments, and the samples collected may not be suitable for cultivation when they reach the laboratory [ 15 ]. Therefore, in countries with both endemic and sporadic anthrax, real-time PCR should be a preferred method for detecting B. anthracis in tissue samples.…”

Section: Discussionmentioning

confidence: 99%

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A Suggested Diagnostic Approach for Sporadic Anthrax in Cattle to Protect Public Health

et al. 2021

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The repeated occurrence of anthrax in grazing animals should be a reminder of a widespread presence of Bacillus anthracis spores in the environment. Its rapid diagnosis is critical to protect public health. Here, we report a case of anthrax in cattle that was investigated using conventional and molecular methods. In 2015, six cows suddenly died within three days and the number of dead animals increased to a total of 12 within two weeks. At necropsy, anthrax was suspected. Therefore, spleen tissue samples were collected (from 6/12 animals) and laboratory tests (microscopy, cultivation, and real-time PCR) performed. The results of tissue staining for microscopy and cultivation were in congruence, while B. anthracis real-time PCR outperformed both. Spleen tissues from all six animals were real-time PCR-positive, while B. anthracis was successfully cultivated and detected by microscopy from the spleen of only three animals. Additionally, the ear tissue from another (1/12) cow tested positive by real-time PCR, supporting the suitability of ear clippings for molecular confirmation of B. anthracis. Genotyping of the isolates using multiple-locus variable-number tandem repeat analysis (MLVA) revealed a common source of infection as all three typed isolates had an indistinguishable MLVA genotype, which has not been observed previously in Europe. The results indicate that molecular testing should be selected as the first-line tool for confirming anthrax outbreaks in animals to ensure timely protection of public health.

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Section: Discussionmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

A Suggested Diagnostic Approach for Sporadic Anthrax in Cattle to Protect Public Health

et al. 2021

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“…In Outbreak 2, we detected B. anthracis DNA in swabs taken from the dried meat of one of the index animal cases (goat). This finding contributes to the literature on the utility of dried animal products as a useful substrate for anthrax detection in low income countries when other samples, such as blood, are not available at the time of investigation [29]. Due to the extensive practice of fasting in Ethiopia-in which observers of the Ethiopian Orthodox faith abstain from consumption of all animal products for around 180 days each year-meat is frequently dried for later consumption in the non-fasting season.…”

Section: Discussionmentioning

confidence: 72%

First PCR Confirmed anthrax outbreaks in Ethiopia—Amhara region, 2018–2019

et al. 2022

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Background Anthrax is a disease that affects humans and animals. In Ethiopia, anthrax is a reportable disease and assumed to be endemic, although laboratory confirmation has not been routinely performed until recently. We describe the findings from the investigation of two outbreaks in Amhara region. Methods Following reports of suspected outbreaks in Wag Hamra zone (Outbreak 1) and South Gondar zone (Outbreak 2), multi-sectoral teams involving both animal and public health officials were deployed to investigate and establish control programs. A suspect case was defined as: sudden death with rapid bloating or bleeding from orifice(s) with unclotted blood (animals); and signs compatible with cutaneous, ingestion, or inhalation anthrax ≤7 days after exposure to a suspect animal (humans). Suspect human cases were interviewed using a standard questionnaire. Samples were collected from humans with suspected anthrax (Outbreak 1 and Outbreak 2) as well as dried meat of suspect animal cases (Outbreak 2). A case was confirmed if a positive test was returned using real-time polymerase chain reaction (qPCR). Results In Outbreak 1, a total of 49 cows died due to suspected anthrax and 22 humans developed symptoms consistent with cutaneous anthrax (40% attack rate), two of whom died due to suspected ingestion anthrax. Three people were confirmed to have anthrax by qPCR. In Outbreak 2, anthrax was suspected to have caused the deaths of two livestock animals and one human. Subsequent investigation revealed 18 suspected cases of cutaneous anthrax in humans (27% attack rate). None of the 12 human samples collected tested positive, however, a swab taken from the dried meat of one animal case (goat) was positive by qPCR. Conclusion We report the first qPCR-confirmed outbreaks of anthrax in Ethiopia. Both outbreaks were controlled through active case finding, carcass management, ring vaccination of livestock, training of health professionals and outreach with livestock owners. Human and animal health authorities should work together using a One Health approach to improve case reporting and vaccine coverage.

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“…For B. anthracis , DNA extracts (n = 93) from animal carcasses sampled in northern Tanzania between 2016 and 2018 were analysed. All sample extracts had tested positive by qPCR for three regions of the B. anthracis genome ( cap, lef and PL3 [27]), with one exception where cap failed to amplify. Taking the highest of the three Ct values per sample, the Ct values ranged from 19 to 37 (median = 25).…”

Section: Methodsmentioning

confidence: 99%

Target-enrichment sequencing yields valuable genomic data for difficult-to-culture bacteria of public health importance

Dennis

Mable

Brunelle

et al. 2022

Preprint

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Genomic data contribute invaluable information to the epidemiological investigation of pathogens of public health importance. However, whole genome sequencing (WGS) of bacteria typically relies on culture, which represents a major hurdle for generating such data for a wide range of species for which culture is challenging. In this study, we assessed the use of culture-free target-enrichment sequencing as a method for generating genomic data for two bacterial species: 1) Bacillus anthracis, which causes anthrax in both people and animals and whose culture requires high level containment facilities; and 2) Mycoplasma amphoriforme, a fastidious emerging human respiratory pathogen. We obtained high quality genomic data for both species directly from clinical samples, with sufficient coverage (>15X) for confident variant calling over at least 80% of the baited genomes for over two thirds of the samples tested. Higher qPCR cycle threshold (Ct) values (indicative of lower pathogen concentrations in the samples), pooling libraries prior to capture, and lower captured library concentration were all statistically associated with lower capture efficiency. The Ct value had the highest predictive value, explaining 52% of the variation in capture efficiency. Samples with Ct values ≤ 30 were over 6 times more likely to achieve the threshold coverage than those with a Ct > 30. We conclude that target-enrichment sequencing provides a valuable alternative to standard WGS following bacterial culture and creates opportunities for an improved understanding of the epidemiology and evolution of many clinically important pathogens for which culture is challenging.

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Practical and effective diagnosis of animal anthrax in endemic low-resource settings

Cited by 21 publications

References 33 publications

A Suggested Diagnostic Approach for Sporadic Anthrax in Cattle to Protect Public Health

A Suggested Diagnostic Approach for Sporadic Anthrax in Cattle to Protect Public Health

First PCR Confirmed anthrax outbreaks in Ethiopia—Amhara region, 2018–2019

Target-enrichment sequencing yields valuable genomic data for difficult-to-culture bacteria of public health importance

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