The children entered in twos and threes, timidly threading through a knot of bearded, black-clad al Qaida fighters clustered at the entrance of a decrepit government clinic on a back street of the war-savaged Damascus suburb of Yelda.
Inside, smiling Syrian Arab Red Crescent volunteers steered the toddlers to a bench, where they sat in wide-eyed apprehension, unaware that they were beneficiaries of a rare instance of cooperation between the government of President Bashar Assad and its insurgent foes.
Even as it blocks deliveries of food and other crucial aid, the government allows the Red Crescent through its siege lines into rebel-held areas to immunize children against polio. The visits are part of a U.N.-backed drive to extinguish an outbreak of the highly contagious, crippling childhood disease, which has re-emerged in Syria after an 18-year absence, crossed the border into Iraq and threatens to spread further, borne by a tidal wave of refugees.
Yelda, which is held by fighters of al Qaida's Syrian branch, the Nusra Front, is one of those areas. Red Crescent volunteers, taking advantage of a cease-fire negotiated several months ago, have visited twice to administer oral polio vaccine to children 5 and younger. It's a harrowing trip, with volunteers crossing from army lines through a debris-carpeted quarter-mile of no-man's land before threading their way to a desolate government clinic through checkpoints manned by rebels sporting black uniforms and long beards.
"God curse you, Bashar," several rebels muttered, trying to spot a Syrian jet fighter that thundered over Yelda's main road recently as the latest Red Crescent convoy waited to move into the village.
By day's end, 720 children had received the vaccine.
Immunization requires several doses administered at least two weeks apart.
"We consider one case to be an outbreak," said Sona Bari, a spokeswoman for the U.N. World Health Organization, explaining that for every child who contracts paralytic polio, up to 1,000 others can be carrying the virus and can infect others without ever developing symptoms themselves.
U.N. and Red Crescent officials think they've made significant progress toward halting the spread of the virus. Nearly 3 million children have been immunized in government- and opposition-held areas, and there's only been one case of paralytic polio confirmed this year, they said. That compares with 35 cases last year, most of which occurred in rebel-held areas.
Like everything in Syria, though, that record is disputed. One expert says the U.N. uses too stringent a standard for confirming whether a child has polio and that assessments conducted by an opposition aid organization in rebel-held areas suggest the outbreak is far worse.
"Polio is out of control," said Dr. Annie Sparrow, an intensive care pediatrician and public health expert who teaches at the Icahn School of Medicine at Mount Sinai Hospital in New York.
Beyond dispute, however, is that the besieged areas are perfect breeding grounds for the virus, which is spread through feces, contaminated water, coughing and sneezing.
Government forces deliberately have targeted health care professionals and facilities in rebel-held areas, say U.N. investigators and human rights groups, and tens of thousands of civilians inside the encirclements are suffering from malnutrition and shortages of medicines. Water supplies are befouled or shut, power is nonexistent or supplied by generators, and sanitation systems are wrecked.
A McClatchy correspondent who accompanied the Red Crescent convoy into Yelda found it ravaged by street battles and regime airstrikes. Multistory buildings have collapsed in on themselves like massive decks of concrete cards. Bomb craters pit the streets.
Precisely how polio returned to Syria remains a mystery. The strain of wild type 1 poliovirus _ the most virulent kind _ that's been found in Syria has been traced to one in Pakistan, prompting the Syrian government to blame the outbreak on foreign jihadis who've descended on the country to fight with Nusra and another radical Islamist group, the Islamic State of Iraq and Syria.
But Dr. Mohammad Hazem Bakleh, the Syrian Red Crescent official who oversees the immunization operations, said that hadn't been confirmed, and he noted that similar strains have been found in sewers in Israel and Egypt, although there have been no polio outbreaks there.
Red Crescent and United Nations officials point to the single case they've confirmed this year in asserting that major headway has been made toward halting the disease's spread in Syria. Thousands of independent monitors are going door-to-door in the country, seeking out children who haven't been immunized.
It's a measure of the threat, said Elizabeth Hoff, the World Health Organization's representative in Damascus, that both sides are cooperating in the program.
The government restricts deliveries of medical supplies _ such as intravenous fluids and syringes _ needed to halt outbreaks of diarrhea, measles and other illnesses but that also could be used to treat wounded rebels. Yet it's imposed no such impediments on the polio immunization program, she said.
Both sides "realize the risk of this spreading not only in Syria, but the risk of Syria becoming an epicenter of polio," Hoff said.
That risk was made clear this spring, when the virus paralyzed a 6-month-old boy in Baghdad _ Iraq's first polio case in 14 years. The virus was "exported" from Syria, Hoff said.
And there are an estimated 300,000 Syrian children under the age of 5 who are living in besieged areas or in places too remote to be reached easily.
It took weeks for the Red Crescent to overcome suspicions on both sides when it received permission late last year for its volunteers _ many of whom are university students _ to cross front lines to administer oral polio vaccines, said the Red Crescent's Bakleh. Both sides fired on convoys, though none of the 37 volunteers who've died during the more than three-year war have been killed on polio immunization runs.
"We couldn't get the vaccine to some areas because of the fighting," said Bakleh, who has a photograph in which he's holding a bullet that had buried itself in the back of a car seat on which he was sitting. "Even the army stopped the Red Crescent from bringing supplies to the rebel side at the beginning, thinking we were carrying weapons."
Volunteers also had to overcome widespread ignorance among ordinary people about polio and fears about the oral vaccine.
"Before the crisis, we'd forgotten about this disease," said Tamman Muhrez, 34, a civil engineer who's been a Red Crescent volunteer for more than 16 years. He described one incident in which "volunteers had to take the polio vaccine themselves to prove to villagers that it was safe."
The McClatchy correspondent was permitted into Yelda in his own vehicle for about 40 minutes during the Red Crescent's visit earlier this month. He was forbidden to photograph anything except the children receiving polio vaccine. His driver later said a rebel had demanded 15,000 Syrian pounds, about $88, for the visit.
Rebels kept close watch on the Red Crescent vehicles as they drove deep into a maze of ruined back streets, guided by three young gunmen astride a motorcycle. Only a few women were seen. All wore body-length black dresses. Only their eyes were uncovered by black scarves wrapped about their heads.
All the stores appeared shuttered except for two butcher shops in which several whole sides of sheep hung from hooks. Wheat was planted in vacant lots.
A gunman who called himself Abu Noor said that under the terms of the cease-fire, the regime allowed 10 sheep to be brought into Yelda on Wednesdays and about 3 tons of vegetables every three days. But it's insufficient for the 6,000 families he estimated are living here.
"It meets about 40 percent of the needs," said Noor, who added that there hadn't been any power for 20 days and that water was available from taps for only two hours each day.
More fighters stood outside the government clinic as the convoy pulled up and the Red Crescent volunteers poured out.
The one-story building was virtually bare except for dust-covered desks, a ruined dental chair and the bench on which the volunteers sat the children, many of whom had been brought from the neighboring besieged Palestinian refugee camp of Yarmouk.
In ones and twos, they were led into a small office where a volunteer gently pinched their cheeks, puckering their lips open, and administered the vaccine.
A man who gave only his first name, Ghasam, said he'd gone home to fetch his 14-month-old daughter, Malaq, after he saw the convoy drive into Yelda. She was there to have her second immunization.
"Thank God for this program," he said, before carrying her away to receive her drops.
By Jonathan S. Landay
McClatchy Washington Bureau