WEDNESDAY, Jan. 6, 2016 (HealthDay News) -- The Ebola epidemic in West Africa has been a human tragedy of terrible proportion, leaving 11,315 dead since it began in March 2014.
But the epidemic in Guinea, Liberia and Sierra Leone -- the largest Ebola outbreak in history -- also has provided a unique opportunity to study what had been a rare virus, potentially arming researchers with the know-how to protect people against future outbreaks.
A trio of papers in the Jan. 7 New England Journal of Medicine reveal some of what has been learned about the virus, which has sickened more than 28,000 people:
- Women infected with Ebola had a higher survival rate than men, raising questions about what caused this advantage.
- An anti-malaria drug used when doctors ran out of their usual medication wound up reducing patients' risk of death by more than 30 percent.
- The much-hyped strategy of using blood plasma from Ebola survivors to help treat future patients appears to be a bust, offering no significant survival advantage to those who received transfusions.
"The thing these three papers have in common is that they're really showing there's a concerted effort to conduct research on Ebola, and there's a major opportunity to learn more -- so much more -- about Ebola than we ever could prior to the outbreak in West Africa," said Dr. Amesh Adalja, an Ebola expert and senior associate at the UPMC Center for Health Security, in Baltimore.
In the first paper, members of the World Health Organization's Ebola Response Team found that women were less likely to die than men from Ebola infection.
About 63 percent of women died compared with 67 percent of men, even though both genders had a similar risk of contracting the virus, researchers reported.
The WHO team ruled out age, the severity of symptoms and the time it took for the patient to be hospitalized as factors that might explain the advantage women had over men, said Christl Donnelly, a team member and a professor of statistical epidemiology at Imperial College London in England.
"We were not able to identify what drove the observed difference," Donnelly said.
"It does show there may be some interaction with gender and Ebola," Adalja said. "We know that females do face infectious disease differently than males. There are genetic and hormonal differences that could be at play and will give us more of an understanding of who lives and dies with Ebola."
The research team noted that male Ebola patients tended to take about a half-day longer to get to the hospital, which could increase the risk they would transmit the disease to someone else.
The second paper, by a Doctors Without Borders (Medecins Sans Frontieres) team, presents the results of what Adalja called a "natural clinical trial" for an anti-malarial drug combo called artesunate-amodiaquine.
Suspected Ebola patients receive treatment for both Ebola and malaria, Adalja said. Patients often are suffering from both diseases, but sometimes patients have malaria that resembles Ebola.
In August 2014, at the peak of the epidemic in Liberia, the Doctors Without Borders team ran out of its first-line anti-malarial medication, artemether-lumefantrine, said study lead author Dr. Iza Ciglenecki.
Patients admitted during this period were given another commonly used anti-malarial drug, artesunate-amodiaquine, said Ciglenecki, project manager of the organization's Initiative for Innovations.
"This situation, in many ways, resembles random allocation of anti-malarial drugs, as it was only determined by the time when the patient came to the treatment center and not by clinicians' preferences nor patients' characteristics," Ciglenecki added.
It turned out that patients given artesunate-amodiaquine treatment were 31 percent less likely to die than those who received the usual treatment, doctors learned.
The results can be read in one of two ways, Adalja said. It could be that artesunate-amodiaquine is somehow effective against Ebola, particularly given that amodiaquine has been shown to have anti-Ebola virus activity in laboratory studies.
But it also could be that the first-line drug, artemether-lumefantrine, is more dangerous than previously thought. "As of now, people maybe shouldn't be using that first-line drug, and should be moving to this other drug," Adalja said.
The third study focused on the practice of treating new Ebola patients with plasma drawn from survivors, in hopes that the plasma contains antibodies that would boost their immune response.
Several of the Ebola patients treated in the United States received these transfusions, and some suspected the plasma might have accounted for the fact that most U.S. patients survived.
But after controlling for other factors, researchers concluded that 84 patients who received the plasma got no benefit over others who didn't get a transfusion.
"They didn't show a benefit, which was something people sort of expected based on earlier data," Adalja said.
For more on Ebola, visit the World Health Organization.