The World Health Organization (WHO) has declared the spread of polio is an international public health emergency.

Outbreaks in Asia, Africa and Middle East are an "extraordinary event" needing a co-ordinated "international response", the agency says.

It recommends citizens of affected countries travelling abroad carry a vaccination certificate.

It says Pakistan, Cameroon, and Syria "pose the greatest risk of further wild poliovirus exportations in 2014."

The WHO recorded 417 cases of polio worldwide for the whole of 2013. For 2014, it had already recorded 68 cases by 30 April - up from 24 in the same period last year.

Polio mainly affects children under five years old.

(BBC)