Nigeria and Cameroon declared polio free

The World Health Organization (WHO) has certified Nigeria and Cameroon to be free of polio, a crippling disease that usually affects children under five.

Afghanistan and Pakistan are now the only countries with cases of the wild polio virus.

The UN health agency is expected to formally present Nigeria with a certificate and also declare Africa free of the wild polio virus.

Nigeria's head of primary health care agency Dr Faisal Shuaib described the achievement as a "proud moment for us and indeed all Nigerians".

Cameroon's Health Minister Malachie Manaouda had on Wednesday announced that the country had been certified free of polio.

Health experts in the country welcomed the development but urged caution.

For a country to be declared polio-free it must ensure high immunisation coverage and prove there have been no transmissions for at least three consecutive years.

It should also maintain a surveillance and outbreak preparedness system.