MPONDWE, Uganda — On Tuesdays and Fridays, an estimated 19,000 people stream down the hill from Congo’s North Kivu province to cross the border into this small town, many of them headed to a sprawling open-air market.

In recent weeks, crossing the border has become more difficult as Ugandan health authorities have beefed up precautions against the spread of the Ebola virus. An outbreak centered in North Kivu is responsible for 105 confirmed or suspected cases, including 67 deaths, according to Robert Redfield, director of the U.S. Centers for Disease Control and Prevention, who has just returned from the area.

Uganda is determined to keep the deadly hemorrhagic fever from spreading to its side of the border. Before travelers are allowed through, they must step in small tubs of chlorinated water to disinfect their shoes, and their temperatures are taken with no-touch thermometer guns aimed at their temples.

A health care worker from the World Health Organization gives an Ebola vaccination to a front-line aid worker in Mangina, Democratic Republic of Congo.

Uganda moved quickly, imposing the precautions a week after the latest outbreak was declared Aug. 1. It has found six suspected cases at this crossing, but laboratory tests cleared them all.

“So far, we have not gotten any case of Ebola,” Ithungu Honorata, a nurse who oversees the screening effort, said Friday. “But we don’t want it to come to Uganda.”

The latest Ebola outbreak, Congo’s 10th, was declared just a week after a smaller one was quelled in another part of the country.

It comes four years after the Ebola epidemic in Liberia, Sierra Leone and Guinea killed more than 11,000 people, sickened more than 28,000 and sparked panic about travel in other parts of the world, including the United States.

The current outbreak is still escalating, according to Redfield and workers at nongovernmental organizations that have rushed in to treat victims and interrupt the spread of the disease.

“Really, in two weeks, we’ve gone from 24 cases to 105 cases,” Redfield said, mainly because many health workers at a hospital in the town of Mangina, where the outbreak began, became infected when they treated early patients without recognizing that they had Ebola and therefore did not take adequate precautions. The disease spreads through contact with the bodily fluids of victims, putting health workers and patients’ family members at greatest risk.

“In the next couple of weeks, we’ll have greater clarity” about the scope of the problem, Redfield said.

“The scary thing is that we are above 100 cases already,” said Michelle Gayer, director of emergency health for the International Rescue Committee, a nonprofit organization that is helping in the region. But she said it will be another week before health authorities can begin to assess fully how bad the outbreak may become.

“Everyone is concerned, rightfully so, that there are still cases coming,” said Karin Huster, emergency coordinator for Doctors Without Borders, who is in Beni, a city in the affected area of Congo.

Several factors make this outbreak challenging. Years of conflict between militias and the government have put large numbers of people on the move and weakened the region’s health infrastructure. The instability also makes it difficult to travel to outlying areas where cases have been discovered, such as Oicha, without military protection.

But unlike four years ago, when Ebola tore through a portion of West Africa, authorities now have a vaccine and several experimental treatments that were developed in the interval.

Redfield said that nearly 3,000 people have been vaccinated, with 400 to 600 more receiving the vaccine each day.

About a dozen confirmed cases have been treated with two experimental therapies, including one developed at the U.S. National Institutes of Health. All of the treated patients are alive, he said.

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