Africa declared free of wild polio

Q. What is the news?

A. Africa has been declared free from wild polio by the independent body, the Africa Regional Certification Commission. Now only the vaccine-derived polio virus remains in Africa.

Q. When a country is certified as free of wild polio?

A. A region is certified as free of wild polio after three years have passed without the virus being detected in any of its countries.

Nigeria is the last African country to be declared free from wild polio.

Q. Where wild polio is still present?

A. Wild polio is still present in Pakistan and Afghanistan.

Q. What is a vaccine-derived poliovirus?

• It is a strain of the weakened poliovirus that was initially included in oral polio vaccine (OPV) and that has changed over time and behaves more like the wild or naturally occurring virus.
• This means it can be spread more easily to people who are unvaccinated against polio and who come in contact with the stool or respiratory secretions, such as from a sneeze, of an infected person. 
• These viruses may cause illness, including paralysis.

Q. How is it spread?

• Oral polio vaccine (OPV) contains an attenuated (weakened) vaccine-virus, activating an immune response in the body. When a child is immunized with OPV, the weakened vaccine-virus replicates in the intestine for a limited period, thereby developing immunity by building up antibodies.
• During this time, the vaccine-virus is also excreted. In areas of inadequate sanitation, this excreted vaccine-virus can spread in the immediate community (and this can offer protection to other children through ‘passive’ immunization), before eventually dying out.