Which statement best describes how West Nile virus was identified in the United States?

• A. Diagnosed due to the keen observations and persistence of a zoo veterinarian
• B. Discovered via routine cattle surveillance
• C. Detected only after equine outbreaks
• D. Identified through hospital-based surveillance

Answer: (A)

Early detection of West Nile virus in the United States came from wildlife and veterinary observations rather than routine animal or human surveillance. A Bronx Zoo veterinarian noticed a puzzling pattern of bird deaths, especially among crows, and pursued samples and reporting to public health authorities. This alert triggered laboratory work that led to the isolation and identification of the virus as West Nile virus. The key lesson is that vivid signals in wildlife health, reported by a dedicated veterinarian, can reveal a new pathogen and spark the investigations that confirm its identity. The other scenarios—routine cattle surveillance, discovery only after horse outbreaks, or hospital-based human surveillance—did not provide the initial clue that led to the identification.