The month-old Ebola outbreak in the Democratic Republic of Congo, which emerged unexpectedly in a dangerous region and quickly soared to over 100 cases, now appears to be fading.
Only a handful of new cases appear each week, and the region's two treatment centers, full until recently, now have fewer than 30 patients in their 78 beds.
More than 3,500 contacts of known cases are being followed, more than 4,000 doses of vaccine have been given and officials feel hopeful enough to allow schools in the area — North Kivu Province, on the eastern border with Uganda — to open as usual on Monday.
However, it is far too early to relax, health experts warned.
“We cannot say the outbreak is under control yet,” said Dr. Oly Ilunga, the country’s health minister, echoing a warning from Tedros Adhanom Ghebreyesus, director general of the World Health Organization.
“While the number of confirmed cases has slowed down lately, we must remain vigilant,” Dr. Ilunga said. “An Ebola outbreak works in waves, and the first wave hit us hard.”
That wave, he explained, comprised people infected before health workers arrived, and these patients may have infected a second wave of family members, neighbors and medical workers who are still in their incubation periods.
“Over the next few days,” he said on Friday, “many contacts will come out of their 21-day surveillance periods, and we’ll know to what extent we managed to break the transmission chain.”
As of Friday, there were 118 confirmed or probable cases and 77 deaths, and the threat of more is still so high that officials have not halted construction of a third treatment center.
If the outbreak does fade out, credit will again go to rapid action by the Congolese government and global health agencies, as well as to a new, highly protective Merck vaccine.
Although five experimental treatments for infected patients recently won approval for emergency use, so far too few patients have received them to draw conclusions about how well they may work.
One reason experts are reluctant to declare the outbreak contained is that some remote towns have not been visited because of armed groups roaming the area.
Thus far, fighting has not hampered the response, said Florence Marchal, spokeswoman for the United Nations peacekeeping mission in the region.
Congolese health workers escorted by peacekeepers were able to safely reach Oicha, the only town in a “red zone” with confirmed Ebola cases.
However, just two weeks ago, Ms. Marchal said, as many as 18 Congolese soldiers were killed in an attack in North Kivu, probably by the Allied Democratic Forces, a Ugandan rebel group.
Ebola experts also said they would not let down their guard because they remembered a brief, deceptive lull in the early days of the 2014 West African outbreak before it reached three capital cities and exploded, killing more than 11,000 people.
But with each new outbreak, medical groups are bringing new technologies and tactics to bear on the disease.
A new vaccine, rVSV-ZEBOV, proved itself in the recent outbreak in Congo’s central Équateur Province that began in April and was declared over on July 24.
Even though the virus had spread from a rural area to a thriving lakeside town and ultimately to a big city, Mbandaka, the outbreak was quickly stopped by inoculating health workers and the rings of contacts of each known case.
Techniques pioneered in that outbreak are playing even more prominent roles in this one.
For example, in Mangina and Beni, the towns at the epicenter, the Ministry of Public Health immediately sent about 150 hospital staff personnel into home quarantine and replaced them with others who had been trained in donning and safely removing protective gear.
To encourage patients to come in, the ministry also made all care at public hospitals free — for any illness.
Then, as soon as possible, health officials vaccinated all medical personnel. Those steps reduced a major risk factor — medical workers who catch the virus from one patient and unwittingly pass it to others before they themselves collapse. (In the early days of any outbreak, most people coming to hospitals do not have Ebola but malaria, bacterial infections or other crises, like difficult pregnancies.)
Soon afterward, Alima, the Alliance for International Medical Action, deployed its new Biosecure Emergency Care Units, which it calls “cubes,” in its treatment center in Beni.
The rooms, made of clear, flexible plastic with sleeves, gloves and bodysuits built into the walls, allow nurses to safely perform about 80 percent of the care an Ebola patient needs without having to put on hot, cumbersome gowns, hoods, rubber aprons, boots and goggles.
Wearing full gear, caregivers can look terrifying, especially to children.
“Now they can see us as human beings,” said Claude Mahoudeau, Alima’s emergency response coordinator.
Nurses can check vital signs, feed patients and change intravenous drip rates, said Augustin Augier, Alima’s secretary general, and may eventually start inserting intravenous needles from outside. Workers must still enter the cube to clean up diarrhea and vomit, unless patients are strong enough to do it themselves and then seal the soiled linens in bags and pass them out through a portal.
The chambers are air-conditioned for comfort. Also, patients’ relatives can safely sit outside and talk to them.
The cubes “sound like a very interesting idea” said Leah Feldman, medical coordinator for the Doctors Without Borders treatment center in Mangina, who said she plans to visit Alima’s center soon.
Her center keeps patients and relatives separated by two rows of waist-high fencing; those who are bedridden can talk on phones.
Families will only bring in their sick if they can see they are well cared for, she said. “It can’t be that they just go inside and come out later in a body bag.”
Medically, the most exciting prospect on the horizon is that, as of Aug. 22, Congo has approved the emergency use of five potential treatments: two antiviral drugs, remdesivir and favipiravir; and three cocktails of antibodies originally found in recovered patients, including ZMapp, mAb114 and Regn3450-3471-3479.
Previously, only about half of Ebola patients were saved if they got supportive treatment, including fluid replacement and fever control, in time.
Being consistently able to cure most patients would be a terrific advance, experts said, reducing the terrifying aura around the virus to one more like that surrounding cholera.
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In the 19th century, cholera swept away millions, and it can still can go on lethal rampages, as it recently has in Haiti, Somalia and Yemen. But cholera can also be controlled and its fatality rate cut to less than 1 percent if vaccines, antibiotics and fluid replacement are deployed quickly.
Few Ebola victims have received the experimental treatments, and the results have not been compiled.
As of Thursday, according to the W.H.O., 19 patients had been given remdesivir, ZMapp or mAb114. One died, two survived and 16 were still on treatment. (Remdesivir is given for 10 days.)
But “Ebola is tricky,” warned Ms. Feldman, a trauma nurse working on her fourth outbreak. “Patients can look like they’re doing better and then crash.”
Despite the lull, the International Medical Corps, a nonprofit group of volunteer doctors and nurses, is still working to complete a 50-bed unit in Makeke.
“The decrease is promising, but I don’t think we can relax,” said Ky Luu, the I.M.C.’s chief operating officer. “When we were tasked to do it, the other two centers were at capacity, and cases could still ramp up.”
Building in such a remote area is not easy. Besides isolation wards, toilets and showers for 50 patients, a center must have a laboratory with generators and freezers, gowning and decontamination areas, screening areas for new patients, bathrooms, kitchens and on-site housing for up to 200 staff.
Even before that, the ground had to be cleared and hundreds of yards of dirt road had to be graded. Because it is the rainy season, heavy equipment was bogged down.
“We’re hiring local people to do it with shovels,” Mr. Luu said.
