As of 1999, what was the global status of wild poliovirus type 2?

• A. It was globally eradicated.
• B. It was circulating in most regions.
• C. It had been replaced by a vaccine-derived strain.
• D. It was confined to a few pockets in Africa.

Answer: (A)

Wild poliovirus type 2 had no active transmission anywhere in the world by that time. Eradication means a wild virus type is no longer circulating globally, a conclusion reached when surveillance shows no cases or detections for an extended period. The last wild-type instance of type 2 was detected in 1999, and thereafter global monitoring found no circulation. So, as of 1999, it was considered globally eradicated. The other options would imply ongoing spread in many regions, confinement to a specific area, or replacement by a vaccine-derived strain, none of which reflected the global absence of wild WPV2 at that time. (Vaccine-derived cases arise from the vaccine strain, not the wild virus.)