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Experimental therapies target Ebola: candidate drugs and vaccines could help end epidemic.

As the Ebola virus outbreak continues to run amok in West Africa, scientists are looking ahead to the possibly pivotal use of experimental drugs and vaccines. It will take months to test, produce and deploy the therapies. But researchers hold out hope that these products--even incompletely vetted--might turn the tide against an illness that has defied public health efforts.

The treatments' use could engender enough hope to encourage people with symptoms--and their close contacts --to come to hospitals, which researchers say would limit the spread of Ebola. Having experimental drugs and especially vaccines in hand could also help in recruiting and maintaining adequate levels of hospital staff, who are at high risk of catching the lethal virus.

Using experimental drugs has downsides: Even if the treatments help some patients, it will be hard to determine their true effectiveness. And failed treatments could exacerbate the despair and distrust already hampering disease control efforts.

Still, public health officials say the situation is dire enough to warrant putting candidate therapies into use after minimal human safety testing. As of September 3, more than 3,500 people had been infected and more than 1,900 had died, the World Health Organization reports. WHO now expects the outbreak will require six to nine months to quell and estimates the caseload could pass 20,000.

The outbreak has hit a thickly populated part of West Africa and spread among Liberia, Guinea, Sierra Leone and Nigeria. None have encountered Ebola before, and the region has been racked by poverty, civil wars, corrupt governments and upheaval. The countries have inadequate health care systems that have suffered even more during the outbreak as some workers abandon their posts.

Daniel Bausch, an infectious disease physician at Tulane University in New Orleans, relates an incident in Kenema, Sierra Leone. Dressed in biohazard gear, he and a WHO doctor entered the hospital there in July and found only two workers amid 55 patients. The nurses were gone. Some were demanding higher wages but many had simply left after seeing their colleagues become sick, he says. Patients were in beds and on the floor; the hospital was contaminated.

"You get into a negative cycle in which it becomes a riskier environment for the nurses who do choose to keep working," he says.

Health officials hope experimental treatments and vaccines will turn the situation around. In August, seven people received a test drug called ZMapp, made by Mapp Biopharmaceutical of San Diego. But supplies of that compound are exhausted and making more will take months. WHO Director-General Margaret Chan said scientists were set to convene in Geneva on September 4 and 5 to examine the most promising experimental treatments and vaccines for fast-track testing in people. In the best-case scenario, WHO officials say, some drugs could reach the field later this year after safety trials in human volunteers. All have so far been tested only in animals (SN Online: 8/29/14).

Having a drug, even an imperfect one, would have an impact beyond the individuals receiving it, Bausch says. A drug could change the mind-set of people who have been in contact with patients but who are not themselves sick. Many hesitate to get tested because hospitals have no way to treat Ebola, he says. Refusal to get tested extends disease transmission if these contacts turn out to harbor the virus and develop an infection. Word of a drug could induce people to come in for testing. "Getting them out of circulation," he says, "could end the outbreak."

But the use of experimental drugs might leave scientists with a poor understanding of the drugs' efficacy since about half of Ebola patients in West Africa survive without treatment, says physician Kevin Donovan of Georgetown University.

On the vaccine front, safety testing of an experimental Ebola immunization by U.S. federal researchers and GlaxoSmithKline started the first week of September. Another vaccine, developed at Canada's National Microbiology Laboratory in Winnipeg, appears next. Both tested well in monkeys. WHO will oversee who gets any semi-tested vaccines, with distribution unlikely until 2015.

Health care workers--who account for some 10 percent of deaths in this outbreak --will be at the front of the line for such shots, says William Schaffner, an infectious disease physician at Vanderbilt University in Nashville. Lab workers and those burying the dead would also get priority for vaccination, WHO officials say.

A lightly tested vaccine comes with caveats. It is unknown whether a single dose will protect fully, Schaffner says, so vaccinated health care workers will still need to don biohazard suits and take other extraordinary precautions. If a vaccinated person comes down with Ebola, he says, it would hurt vaccine credibility.

Giving an experimental vaccine to relatives or other contacts of patients would seem like the next logical step, Bausch says, but could be difficult and might not yield much information about the vaccine. Those living amid the Ebola outbreak might distrust the idea of getting a shot they may not need, and might not welcome later visits to their homes to draw blood to test for immune responses, Bausch says. "There's an incredible stigma" attached to having Ebola, he adds. Even survivors "don't admit they had it."

That could complicate work on another treatment approach, called a "convalescent serum." It would be derived from the blood of an infected person who had fended off the virus and developed antibodies against it. That research is still in its early stages, Bausch says.

Caption: Unregulated travel In West Africa (border between Guinea and Sierra Leone shown) makes it difficult to contain the Ebola virus.

Caption: Ebola expansion West Africa is experiencing the largest Ebola outbreak ever recorded (map shows data as of August 19). Zaire ebolavirus has periodically plagued Central Africa since the 1970s, but this is its first appearance in West Africa.


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Title Annotation:BODY & BRAIN
Author:Seppa, Nathan
Publication:Science News
Geographic Code:60AFR
Date:Sep 20, 2014
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