Anthrax is diagnosed by which method?

• A. Bacterial culture and identification
• B. Virus isolation
• C. Characteristic clinical signs; there is no laboratory test
• D. Agar gel immunodiffusion assay

Answer: (A)

Definitive diagnosis of anthrax relies on isolating Bacillus anthracis from affected material and confirming its identity. Because the disease is caused by a bacterium, growing the organism in culture and then identifying its characteristic features (large Gram-positive rods, nonmotile, often encapsulated, with colony traits on selective media) provides concrete evidence of infection. Molecular or biochemical confirmation can follow, but culture and identification are the standard basis for diagnosis.

Relying on clinical signs alone is unreliable because other conditions can mimic anthrax, and virus isolation is not applicable since this is a bacterial, not viral, disease. Immunodiffusion tests are not used for routine confirmation of anthrax.