A medical officer named Suwarno clambered onto his motorcycle Tuesday, one hand clutching a cooler easily mistaken for the type of bucket that people here use to sell ice cream.

Ida Widaningsih, a stout woman with a black-and-white head scarf, hopped on behind him. She was clasping a list of village children who did not show up for their polio vaccinations as part of Indonesia's massive, one-day immunization drive.

The pair buzzed along the mountain road as far as they could go, then continued on foot through village alleys, down earthen steps carved into the lush hillside, and along narrow dikes between fish ponds, hunting down the holdouts.

Six weeks after health authorities confirmed that a 20-month-old boy from an adjacent hamlet in West Java province had contracted polio, Indonesia is seeking to turn back the global resurgence of the crippling disease at its newest frontier. By nightfall, authorities planned to have immunized about 6.4 million children younger than 5 in the capital, Jakarta, and the nearby provinces of West Java and Banten.

Health officials have reported 16 polio cases in recent weeks, all in West Java, marking the first outbreak since a decade ago, when officials said Indonesia had eradicated the disease. The World Health Organization has concluded that the virus originated in West Africa and was probably carried to Indonesia from Saudi Arabia by either a migrant worker or a religious pilgrim returning home. Once in Indonesia, it was spread through feces and saliva, likely in contaminated water.

Global campaigners had been on the verge of eliminating polio worldwide in 2003 when immunization was temporarily halted in the Muslim-dominated northern states of Nigeria over rumors that vaccination was a Western plot against Muslims. Since then, the virus has flared in Nigeria, raced along the midsection of Africa and skipped across the Arabian desert to reach its easternmost point in the misty mountains of West Java.

By 7 a.m. Tuesday, women cradling babies in traditional slings across their chests were already crowding into the health posts of West Java, about 60 miles south of Jakarta, eager to have their children receive the free vaccines, but skeptical, too.

"I'm scared because of the stories I heard, not only on television but from the next village, about how children got paralyzed and couldn't walk," said Titin, 42, who brought her 4-year-old grandson, Rizki.

"I'm afraid the same thing will happen to him," she said, her brown eyes widening beneath a black head scarf. "I'm terrified."

In Parakan Salak's badminton hall, one of nine posts set up in the village, women pressed against the wooden tables, pushing their children forward and holding their heads back while Suwarno, 40, a local health supervisor with a black vest over his tan civil servant's uniform, squeezed two drops into each child's mouth.

By the time the rush trickled to a halt two hours later, about 190 children had been immunized. But after Suwarno, a man with jet black hair and warm brown eyes, scanned the lists, he reported, "We're still missing 36."

Suwarno grabbed the plaid cooler of vaccines and headed outside to his motorcycle. Widaningsih, 39, the matronly volunteer with fingers stained by ink from marking the hands of vaccinated children, trailed behind.

At the first stop, a run-down Islamic school converted into another health post, volunteers confirmed that 23 of the children on Suwarno's list had been brought there by their parents because it was closer to their homes. But that left more than a dozen unaccounted for, and he was worried some mothers might have balked.

"It's challenging for me," he said, smiling softly. "Most people don't have an educational background, so you have to take it slowly with them."

Suwarno and Widaningsih got back on the motorcycle and headed deeper into the rice paddies before parking on the roadside. They ducked into a narrow passageway between two low homes, rambled past a series of stagnant green fishponds and descended the switchback steps into the valley. After traversing a pair of flimsy wood plank bridges in sandaled feet, they found a home fashioned partly from bamboo along a muddy trail.

"Why didn't you come?" Widaningsih barked at a woman on the porch.

"I didn't know," Ibu Juju, 23, shouted back.

Sheepishly, Ibu Juju called her 4-year-old son out of the house. Suwarno placed the drops in his mouth. Then two more children appeared in the doorway and he repeated the procedure.

Farther along, the pair came to an even smaller house on the banks of a stream.

The occupant of the house, Ibu Evi, 34, clad in a floral dress, also complained about the bother of bringing her children for their doses.

Ignoring her response, Suwarno beckoned to her 4-year-old son. "Come here, Rifad. I'll give you something sweet, just like ice cream." One after another, all four of Ibu Evi's children opened their mouths for the drops.

Ultimately, Suwarno and Widaningsih found all of the missing children, including a boy they happened across at a tea plantation, with his 85-year-old grandmother.

Across Parakan Salak, officials reported a high rate of success Tuesday. A total of 907 children were immunized, including 76 tracked down after they failed to appear at a health post. But the record was not perfect. Besides several dozen youngsters who were sick or traveling, the parents of nine children refused to have them immunized. Local police, army officers and Muslim clerics will try to persuade the parents to cooperate, local officials said.

For Suwarno and Widaningsih, the toughest sell was at a small home on the edge of sprawling tea fields. Approaching the porch, Widaningsih had to summon the occupant repeatedly before a young woman, Yanti, emerged, holding her 2-month-old niece in a sling.

"I didn't think she would handle taking the vaccine," Yanti argued. "She's too young. It's not good for her."

Suddenly, the infant's mother, Ipoh, appeared on a rise in the trail, returning from work in the paddies. Thin and looking older than her 30 years, Ipoh echoed the objections. "I didn't bring her because her body isn't strong enough to handle the vaccine," she scolded, tired eyes flashing her displeasure.

But by that time, Suwarno had squeezed a pair of droplets into the baby's mouth.

Special correspondent Yayu Yuniar contributed to this report.

Suwarno, right, a health supervisor in Parakan Salak village, administers the polio vaccine to Firman, 4, while his grandmother holds him still.