Since 1988, when the polio-eradication plan began, the global incidence of the disease had been reduced by 99 per cent with the number of countries affected by endemic polio down from 125 to just three by the end of 2012.
However, a resurgence of the viral disease, which can be completely prevented by oral vaccination, has occurred this year and in 2013 in several countries across Asia, the Middle East and Africa where vaccine campaigns have failed to reach high-risk children.
An emergency committee of the WHO said in a statement yesterday that the international spread of polio to date in 2014 constitutes an “extraordinary event” and that there is a serious public health threat to other countries where vaccination is incomplete.
“If unchecked, this situation could result in failure to eradicate globally one of the world’s most serious vaccine-preventable diseases. It was the unanimous view of the committee that the conditions for a public health emergency of international concern have been met,” the committee said.
At the end of April, there were 68 confirmed cases of polio this year, compared with 24 at the same point last year. Three countries – Pakistan, Cameroon and the Syrian Arab Republic – were identified as places that had exported polio to other countries in 2014.
Wild poliovirus was also found to be present in Afghanistan, Equatorial Guinea, Ethiopia, Iraq, Israel, Somalia and Nigeria. Although these countries were not identified as exporting the virus, there was a serious risk that people could carry it with them when travelling, particularly from Nigeria which has a history of spreading polio across borders, the WHO said.
The polio virus typically affects children under five and can cause severe paralysis and death. It is usually spread in water contaminated with human faeces and although there is no specific treatment or cure, it can be prevented by a vaccine taken by mouth.
The WHO’s global polio-eradication campaign, backed by the Bill and Melinda Gates Foundation, was based on administering the vaccine to as many children as possible in the at-risk countries to eliminate the disease completely in the wild. However, it has met opposition in some Muslim regions, which has been made worse in conflict zones where vaccine administration is even more difficult.
“Until it is eradicated, polio will continue to spread internationally, find and paralyse susceptible kids,” said Bruce Aylward, the head of the polio-eradication campaign at the WHO.
In 2013, polio reappeared in Syria, sparking fears that the civil unrest there could ignite wider outbreaks across the region. The virus has also been identified in the sewage systems of Israel, the West Bank and Gaza, although no cases have been identified.
In February, the WHO found polio had also returned to Iraq. It is already circulating in eight other countries: Pakistan, Nigeria, Ethiopia, Afghanistan, Equatorial Guinea, Cameroon, Somalia and Kenya.
An independent monitoring board set up by WHO to assess progress in eradicating polio has described the problems as “unprecedented” and said the situation in Pakistan was “a powder keg”. Dozens of Pakistani polio workers have been killed in the last two years and the vast majority of new cases are in Pakistan.