– Until recently, polio was considered a poor man’s problem in Pakistan — a crippling virus that festered in the mountainous tribal belt, traversed the country on interprovincial buses, and spread via infected children who played in the open sewers of sprawling slums.

But since the World Health Organization declared a polio emergency here this month — identifying Pakistan, Syria and Cameroon as the world’s main reservoirs of the virus — the disease has become an urgent concern of the wealthy, too.

A WHO recommendation that travelers not leave Pakistan without a polio vaccination certificate has caused confusion. Doctors, clinics and hospitals have been inundated with inquiries. The association of travel agents has reported “panic” among air travelers.

“It’s very worrisome,” said Mohammad Akbar Khan, a passenger at the Karachi airport on Thursday. “We just found out about this on the news, and we’re trying to find out what to do.”

The government, which is scrambling to meet the WHO requirement, says it needs two weeks to make arrangements at airports and buy more vaccines. But to most Pakistanis, it is a jolting reminder of the gravity of a crisis that has been quietly building for years, and which is now spilling into other countries, threatening to undo decades of efforts to eradicate polio across the globe.

Pakistan has the most cases

This year Pakistan reported 59 new polio cases, by far the most of any country. The WHO had reported 68 cases worldwide as of April 30.

Instability is driving the crisis. The Taliban, which had long opposed the vaccinations as part of what its leaders said was a Jewish conspiracy, has stymied immunization efforts in the northwest and the tribal belt, where infection rates are highest. The Taliban have forbidden vaccinations in North Waziristan, and killed vaccination teams in other areas.

Suspicions among the Taliban and others that the vaccination campaign was an espionage effort gained currency after 2011, when a covert, CIA-financed vaccination campaign used to try to find Osama bin Laden came to light.

The sense of urgency that has gripped health professionals for years, however, was largely absent among the upper class. “There was a total disconnect” in society, said Anita Zaidi, a member of the National Immunization Technical Advisory Group.

Ambivalent responses

Some of the highest refusal rates for polio vaccination were recorded in wealthy Karachi neighborhoods, where residents had little faith in public health care, Zaidi said. Now, the vaccination requirement has drawn an ambivalent response from the wealthy.

Ibrahim Shamsi, a textile exporter who travels to Canada, called it “a lot of botheration.” He said, “I’m sure I was vaccinated as a child so I don’t know why I need to do it now.”

For some experts, the worry is that immunizing all travelers will divert scarce resources from efforts to fight polio where it is most prevalent. Zulfiqar Bhutta of the Center for Excellence in Women and Child Health at Karachi’s Aga Khan University, said the travel advisory was “unfortunate,” and would foster an erroneous sense that polio is a universal problem in Pakistan.

“It’s a geographic problem, and this will take the pressure off the hot spots,” he said.

One such hot spot is on the edge of Karach. Buses filled with Pashtuns, fleeing poverty or conflict in the northwest, enter the city every day; some are unwittingly carrying the polio virus from areas where infection rates are highest.

On Friday morning, a team of eight government health workers boarded passenger buses as they entered the city, administering the vaccine to children under the age of 5.

One vaccinator, Nadir Ali, wove through the crowded aisles with an box filled with vaccines. Children bawled in protest, and passengers looked bemused. “Shh,” one mother said to her crying baby. “You’ve gotten the drops, now quiet.”