The first treatment to show any promise against the deadly Ebola virus has cured one-third of the monkeys it was tested on _ raising hopes that a lifesaving therapy for people may be on the horizon.
Experts said the results represent the biggest advance yet in the quest for a drug against Ebola Hemorrhagic Fever, one of the most feared diseases. World Health Organization doctors said they plan to try the drug on humans during the next outbreak.
"You take the patients from their families, they die in the ward, you bury them. Everybody is dying and you cannot do anything," said WHO Ebola expert Pierre Formenty, speaking from the front line of the latest outbreak in the Republic of Congo. "If you can save one or two, it will be nice to come back and try to save lives and not just control outbreaks by burying people."
In the study, outlined this week in The Lancet medical journal, scientists at the U.S. Army Medical Research Institute of Infectious Diseases used a protein that blocks blood coagulation, considered to be a major problem in the disease.
Although it is called Ebola Hemorrhagic Fever, bleeding only occurs in about 40 percent of cases and is often not the cause of death. The affliction is so named because when there is hemorrhage, it is dramatic. The disease most often involves a shock syndrome where multiple organs shut down at once.
The death rate varies from about 50 percent for milder strains of the virus to about 90 percent for the Zaire strain, which is the type ravaging the community in Mbomo, deep in the bush of the Republic of Congo. Since the outbreak began in October, 31 people have been infected and 29 have died.
Scientists believe the virus cranks up the body's production of a substance called tissue factor, which is involved in making blood clots. The body's ability to regulate the thickness of the blood goes awry, clots start to congest the blood vessels and blood backs up, said the study's leader, Army virologist Thomas Geisbert.
Monkey tests
Many strategies have cured mice and other rodents of Ebola, but when those treatments were tried in monkeys they didn't work.
In this study, researchers injected 12 monkeys with a high dose of the Zaire strain of the Ebola virus, which is 100 percent fatal in monkeys.
Then, starting either 10 minutes after the lethal injection or 24 hours later, the scientists gave nine of the monkeys daily shots of the anticoagulation protein for 14 days. The other three monkeys got fake injections.
Tests showed clotting activity was dampened in the monkeys who got the treatment.
Three of the nine monkeys treated, or 33 percent, lived. All the monkeys who received the fake treatment died.
"We saved the lives of three out of nine monkeys. They are still eating biscuits in my lab. The virus is gone. They are healthy. They are cured," Geisbert said.
Almost as impressive was the finding that those monkeys that were treated but died anyway survived for an average of 12 days _ about four days longer than monkeys who had not been given the treatment.
Experts said that delay in death could be crucial.
"What we're doing with Ebola is we're buying time. The difference between Ebola and AIDS is that with Ebola, you do have the possibility of an immune response and to get well _ if you can hang around long enough," said C. J. Peters, director for biodefense at the Center for Biodefense and Emerging Infectious Diseases at University of Texas Medical Branch in Galveston, Texas.
"It remains to be seen whether that's going to be enough time for the immune response to kick in," said Peters, who was not connected with the research. "If the immune response doesn't kick in, you still have something that will buy you time and hopefully we'll have an antiretroviral drug some day."
Encouraging for humans
Peters said the monkey results are encouraging for humans because they provide a very stringent test. If anything, he said, death rates from Ebola are higher in monkeys than in humans.
Experts say any treatment would need to be used in conjunction with a rapid diagnostic test to catch the disease early.
In another advance in the battle against Ebola, WHO scientists reported success with a new diagnostic test they used for the first time in the Mbomo outbreak.
In a telephone interview with The Associated Press, Formenty said a simple dipstick that turns blue in the presence of Ebola seems as accurate as genetic tests that are not practical for rural areas of Africa, where most Ebola outbreaks occur.
Emergency workers usually try to determine who has Ebola by observing patients' symptoms and asking about their contacts. Formenty said the test, which produces results in half an hour, helps identify Ebola patients quickly.
Matthias Borchet, an epidemiologist at the London School of Hygiene and Tropical Medicine who was not involved with developing the test, called it an important advance.
"If you have somebody who's been in touch with someone with Ebola and now develops fever, it's a pretty difficult decision whether to isolate him," he said. "If you put him in the isolation ward with all the other Ebola patients and he turns out to be a malaria case you have exposed this poor guy to considerable risk."
Geisbert said that with the treatment, the new diagnostic test and recent encouraging test results on a vaccine, more progress has been made against Ebola in the last 18 months than in all the time since the disease was identified in 1976.