Infectious bacteria as biological warfare agents: mechanisms, epidemiological threats, and defense strategies.

Infectious bacteria remain among the most plausible agents for deliberate biological attack because they combine environmental robustness, low infectious dose, and the capacity for rapid, severe disease. This review synthesizes current knowledge on major bacterial biowarfare threats including Bacillus anthracis, Yersinia pestis, Francisella tularensis, Brucella spp., and Clostridium botulinum across three levels: transmission routes, molecular pathogenesis, and defense strategies. We summarize how aerosol, food-water, and vector-borne pathways, together with globalization and urban crowding, shape outbreak potential, and contrast non-contagious threats such as inhalational anthrax with highly transmissible pneumonic plague. At the mechanistic level, we highlight convergent virulence platforms capsules and stealth surfaces, intracellular survival programs, type III/VI secretion systems, and toxins such as anthrax lethal toxin and botulinum neurotoxin that delay immune recognition and compress the window for effective intervention. We then review advances in surveillance and countermeasures, including portable PCR and CRISPR-based diagnostics, next-generation anthrax vaccines, antibiotics and antitoxins for plague and botulism, and emerging decontamination technologies for persistent spores. Finally, we discuss the integration of these tools within CBRNE incident management and global biosecurity frameworks, emphasizing persistent gaps in environmental remediation, resistance surveillance, and capacity in low-resource settings. Together, these data define priorities for strengthening resilience to bacterial biowarfare and bioterrorism.