By Tom Miles
GENEVA, May 5 (Reuters) - Pakistan's failure to stem the spread of polio triggered global emergency health measures on Monday, with the World Health Organisation (WHO) recommending all residents must show proof of vaccination before they can leave the country.
The emergency measures also apply to Syria and Cameroon, which along with Pakistan are seen as posing the greatest risk of exporting the crippling virus and undermining a U.N. plan to eradicate it by 2018.
Pakistan is in the spotlight as the only country with endemic polio that saw cases rise last year. Its caseload rose to 93 from 58 in 2012, accounting for more than a fifth of the 417 cases globally in 2013.
The virus has recently spread to Afghanistan, Iraq, Israel and Syria, and has been found in sewage in the West Bank, Gaza Strip and greater Cairo, said WHO assistant director general Bruce Aylward. It also appeared in China two years ago.
"In the majority of these reinfected areas, the viruses circulating actually trace back to Pakistan within the last 12-18 months," Aylward told reporters on a conference call.
Pakistan has called an emergency meeting of senior provincial and federal health officials for Wednesday to finalise how to implement the new requirements.
"The best option would be vaccinating the passengers at the airport departure where polio vaccination cards would be issued to the passengers. Human resource and vaccines would have to be worked out for the purpose," State Minister for Health Services Saira Afzal Tarar said in a televised broadcast.
"It would be most practical as people often have to fly in emergencies."
Aylward said Pakistan had done "tremendous" work to restore security in Peshawar after deadly attacks on health workers had impeded the fight against polio. The race to meet a target to eradicate polio by 2018 was still feasible, he said.
"In terms of the 2014 working target to try and stop transmission, from the data presented, clearly Pakistan would be the only country that would be considered 'off track' in terms of its ability to meet that deadline," he added.
WHO chief Margaret Chan declared the resurgence of the disease to be a public health emergency of international concern, the first such designation since a 2009 flu pandemic.
The travel restrictions should stay in place until there is a whole year with no new exports of the disease, or six months if the countries can show they have carried out high quality eradication activities in infected and high risk areas.
The WHO's emergency committee, an independent group of experts that drew up the recommendations, will meet in three months to assess the countries' actions, or sooner if needed.
The steps published on Monday were the minimum actions that could be taken without unnecessarily disrupting travel or trade, but much stronger measures could have been recommended, Aylward said. Those include full vaccination programmes, restrictions on more countries and recommendations on countries of arrival.
The WHO says 10 million people are walking today thanks to efforts to wipe out the disease, which mainly affects children under five years old. It says economic models show eradicating polio would save at least $40-50 billion over the next 20 years.
Polio passes easily from person to person and can spread rapidly among children, especially in the kind of unsanitary conditions endured by displaced people in war-torn regions, refugee camps and areas where health care is limited.
The virus invades the nervous system and can cause irreversible paralysis within hours. The WHO has repeatedly warned that as long as any single child remains infected with polio, children everywhere are at risk.
There is no cure for the disease but it can be prevented by immunisation. The polio vaccine, administered multiple times, can protect a child for life. (Reporting by Tom Miles, additional reporting by Maria Golovnina in Islamabad; editing by Stephanie Nebehay and Tom Heneghan)