Nigeria is one of the three remaining poliovirus reservoirs in the world and poses a high risk of re-infecting polio-free areas in the entire west and central Africa.

• 尼日利亚是世界上三个脊髓灰质炎疫源地之一，可能给整个西非和中非地区带来脊髓灰质炎病毒传入的危险。