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

Abstract

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.

Identification of the molecular characteristics of Bacillus anthracis (1982-2020) isolates in East Indonesia using multilocus variable-number tandem repeat analysis

“…No other lineage of B. anthracis isolates circulating in East Indonesia was found. Other molecular methods, such as extended MLVA assay (MLVA-15, MLVA-25, or MLVA-31), WGS, and canonical SNP, have been recommended for better comparative analysis and genetic study in relation to B. anthracis [ 14 , 15 , 18 - 22 , 24 , 25 , 51 - 54 ]. Further studies are needed that consider the additional loci for VNTR analysis compared to this study.…”

“…A genetic diversity study of B. anthracis has been performed worldwide using several techniques, such as amplified fragment length polymorphism [ 6 ], multilocus variable-number tandem repeat (VNTR) analysis (MLVA) [ 7 - 22 ], single-nucleotide polymorphism (SNP) [ 1 , 2 , 6 , 7 , 12 , 14 - 19 , 23 - 27 ], and whole-genome sequencing (WGS) [ 1 , 2 , 6 , 7 , 22 , 23 , 28 ]. MLVA detects VNTRs through polymerase chain reaction (PCR) based on target genes, which usually contain low-frequency mutations in the bacterial genome [ 29 - 31 ].…”

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“…The results of tissue staining for microscopy and culture were similar, whereas real-time PCR outperformed both methods of identification. The test of splenic tissues from all six animals was positive for anthrax in case of using realtime PCR, whereas B. anthracis were successfully cultured and detected by microscopy in spleens from only three animals [62]. The results suggest that molecular testing should be chosen as the first-line tool for confirming the animal anthrax outbreaks to ensure timely public health protection.…”

Handling of Outbreaks of Anthrax: Future Perspectives and Challenges

“…✓ Anthrax should be suspected in any animal that dies suddenly and without warning (especially ruminants) (Avberšek et al 2021). ✓ The diagnosis can be confirmed by aseptic conditions drawing deceased blood from a peripheral vein (e.g., the jugular vein or the ear vein) by using a suitable dye to analyze a sample of blood for the existence of the capsule.…”