The World Health Organisation (WHO) said the world would soon be left with only one remaining wild poliovirus as it is expected to announce the eradication of the type-3 virus.
According to WHO, since the UN health agency launched a global initiative in 1988 to wipe out the virus, infection numbers had so far dropped by 99 percent, preventing 18 million cases of paralysis.
A WHO spokesman, Christian Lindmeier, said in Geneva that the eradication of type-3 would likely be certified on Thursday, to coincide with World Polio Day.
No infection with this type had been detected since a case in Nigeria in 2012.
“This shows us that the tactics are working, as individual family lines of the virus are being successfully knocked out.
“Type-2 has previously been eradicated, with the last case detected in India, in 1999.
“Only poliovirus type-1 remains in circulation, but it is restricted to border areas in Pakistan and Afghanistan,’’ Lindmeier.
However, Lindmeier warned that immunisation rates must be kept at high levels, to prevent the spread of polio from vaccines that use a weak but still active virus.
The Philippines saw its first polio case in decades in September, after unsanitary vaccination conditions allowed the virus to spread to children who had not been immunised.
According to WHO, there has been a similar individual case in African countries.
Such back-door infections could only be prevented if the entire population were immunised.