Phenotypic and genotypic characteristics ofBacillus anthracis associated with the occurrence of anthrax cases in East Java, Central Java, and Yogyakarta, Indonesia

Background and Aim: Anthrax is a zoonotic disease caused by Bacillus anthracis, a spore-forming bacterium capable of
long-term environmental persistence. In Indonesia, anthrax has been reported in 22 provinces, with East Java, Central Java, and Yogyakarta identified as persistent endemic regions. Understanding the phenotypic and genetic characteristics of local B. anthracis isolates is critical for informing targeted control strategies under the One Health framework. This study aimed to characterize the phenotypic and genotypic profiles of B. anthracis isolates collected between 1990 and 2021 from three anthrax-endemic provinces in Java, Indonesia, and to identify potential environmental and epidemiological risk factors influencing transmission.

Materials and Methods: A total of 28 isolates obtained from environmental and animal sources across 12 districts were
examined using conventional phenotypic methods and confirmed by multiplex polymerase chain reaction (PCR) targeting
Ba813, lef (pXO1), and capC (pXO2) genes. Laboratory data were interpreted alongside epidemiological and environmental
information within a One Health framework.

Results: All isolates displayed classical phenotypic traits of B. anthracis: Gram-positive morphology, non-hemolytic,
non-motile, capsule formation, and sensitivity to penicillin, tetracycline, and ciprofloxacin. PCR results confirmed the presence of both chromosomal and plasmid virulence markers. Notably, consistent traits across isolates indicated genetic homogeneity among circulating strains. Risk factors contributing to anthrax persistence included inadequate vaccination coverage, livestock movement through trade routes, the slaughter of infected animals, poor carcass disposal, environmental spore survival, and traditional practices such as “Purak” slaughter.

Conclusion: This study provides novel insights into the virulence and genetic stability of B. anthracis in three Indonesian provinces. The findings emphasize the need for integrated control measures that include enhanced surveillance, public education, vaccination campaigns, and environmental decontamination. A robust One Health approach is essential for the sustainable management and eventual eradication of anthrax in endemic regions.