Monkeys infected with the Ebola virus survived after being treated with an experimental drug in a study that suggests the drug may be effective even after severe symptoms are present.
Monkeys were given three doses of the antibody-based treatment ZMapp starting three to five days after being infected with a lethal dose of Ebola. All 18 monkeys treated with ZMapp survived, while three that were not given the medicine died, according to the results published in the journal Nature.
"It is a really, really important study" as it is the longest researchers have waited after infecting monkeys with Ebola to protect all of them with a drug, said Thomas Geisbert, a virologist at the University of Texas who was not involved in the research.
Some Ebola patients have been treated with ZMapp, though the maker of the experimental vaccine, Mapp Biopharmaceutical, said its supply was exhausted. Three health-care workers in Liberia have also been treated with the drug. Liberian officials have confirmed that one of them died.\
The current outbreak had made more than 3,000 people ill and killed 1,552 as of last Tuesday in Liberia, Sierra Leone, Guinea and Nigeria, putting it on a pace to cause more deaths than all previous Ebola outbreaks combined, and prompting the World Health Organisation to declare it a global health emergency.
More than 20,000 people may be infected with Ebola before the outbreak in West Africa was controlled, the WHO said.
The Mapp drug is one of several vaccines and drugs being developed. GlaxoSmithKline and the US National Institutes of Health are planning to start human trials of an Ebola vaccine as soon as this week. Inserm, the French national health institute, is talking with Guinea health authorities about human trials of drugs from Fujifilm Holdings and Tekmira Pharmaceuticals.
While previous research has shown various treatments can protect monkeys against Ebola, in most of the studies the animals were treated with the drugs shortly after exposure to the virus, before bad symptoms were present, Geisbert said. In the new study, however, most of the animals had fevers, abnormal blood cell counts, or other signs of disease by the time they were given ZMapp.
Geisbert, who wrote a commentary accompanying the study in Nature, said the next step would be to perform a safety trial of the medicine in humans.