NEW ORLEANS — Experimental new treatments for Ebola appear to be working effectively in the most recent outbreak in Central Africa, an expert reported at a medical conference here on Wednesday.
The death rate was 43 percent among patients in the Democratic Republic of Congo who received one or more of four experimental treatments, said Dr. William A. Fischer II, an emergency care specialist at the University of North Carolina at Chapel Hill.
If the count excluded Ebola patients who were within hours of death when they arrived at the hospital, the fatality rate would be 32 percent, he added.
By contrast, about 68 percent of Ebola patients in hospitals before the new treatments were approved had died.
Effective treatments, combined with a new vaccine, may revolutionize efforts to turn back Ebola, one of the world’s deadliest plagues. The vaccine itself protects health care workers tending to patients, as well as family members and others who have been in contact with them and may be infected.
“I do think the tide is changing,” said Dr. Fischer, as he presented preliminary data at the annual meeting of the American Society of Tropical Medicine and Hygiene. “I do think we’re in a new world.”
Dr. Fischer has treated Ebola patients in Congo’s current outbreak and in previous ones, including the epidemic in West Africa that began 2013 and ultimately killed about 11,000 people.
Of the 276 known victims in Congo’s outbreak, only 113 patients who reached hospitals after August 12 have received any of the new treatments. The results were very preliminary, Dr. Fisher acknowledged, and it is too early to draw firm conclusions about how well each of the four treatments works.
In early animal trials, all four treatments worked 90 percent to 100 percent of the time in rhesus monkeys who received them up to five days after infection with Ebola.
The four treatments are: remdesivir, an antiviral drug; mAb114, a human antibody cloned from a survivor of an outbreak years ago in Zaire; REGN-EB3, a cocktail of cloned human antibodies; and ZMapp, a cocktail of antibodies made from a blend of human and mouse proteins.
Remdesivir can be injected quickly, but must be given once daily for 10 days. ZMapp must be given for three days in infusions lasting up to five hours. The two others, mAb114 and REGN-EB3, are given in single infusions.
Remdesivir works against all strains of Ebola. The others, as far as is known, work only against the Zaire strain of the virus.
Depending on conditions, different treatments and combinations are used in different patients at the three treatment centers in Congo, Dr. Fischer said.
Serious side effects appear to be few. Some patients receiving treatment have experienced headaches, fever and rapid heartbeats.
Some of the experimental treatments need refrigeration, and not all are available at all sites. Moreover, there are not always enough medical workers on hand to oversee infusions, which must be given very slowly to avoid the risk of anaphylactic shock — an overwhelming immune reaction to foreign proteins.
The North Kivu outbreak seems to have begun in April or May. On July 31, human samples tested positive for Ebola, and the outbreak was officially declared. Health officials in Congo approved all four treatments in August.
All the approvals were “investigational,” meaning that the treatments are experimental but there is evidence they work in animals and are likely to be safe and effective in humans.
An unusual number of children have been infected with Ebola in Congo, Dr. Fischer said. Local health workers suspect that many visited traditional healers for treatment of malaria and were infected with Ebola by other patients there.
As word spreads that effective new treatments are available, he added, Congolese health officials hope that patients will turn first to medical clinics instead.