The World Health Organization said Wednesday that it would convene a group of medical ethicists early next week to wrestle with questions about the use of experimental drugs in the deepening Ebola outbreak in West Africa, which has now claimed the lives of nearly 1,000 people.

The issue has received widespread attention after two U.S. missionaries — infected by the virus while treating patients in Liberia — received doses of an Ebola drug still under development.

The WHO acknowledged that the missionaries’ situation — as well as calls for wider access to that drug and others like it — raised tough questions about whether medicine that has not been proved safe and effective in humans should be used in an outbreak of the magnitude of the one in West Africa. Typically, new drugs go through years of trials before being approved for wide distribution.

Even if the potential benefits clearly outweigh the risks, ethical quandaries remain. Given the limited quantities of many experimental drugs, how do authorities decide who will receive it? Who pays for it? Who is responsible if a drug does more harm than good?

“We are in an unusual situation in this outbreak,” Marie-Paule Kieny, WHO assistant director-general, said in a statement Wednesday. “We have a disease with a high fatality rate without any proven treatment or vaccine. We need to ask medical ethicists to give us guidance on what the responsible thing to do is.”

At least one country, Nigeria, has asked the U.S. Centers for Disease Control and Prevention for access to the treatment that was given to missionaries Kent Brantly and Nancy Writebol, officials said Wednesday.

Currently, no approved treatment or vaccine exists to treat Ebola, a disease that kills 60 to 90 percent of the patients who contract it. There are a handful of promising treatments and vaccines under development, but none has received approval from regulators for mass distribution. And pharmaceutical companies have generally shown little appetite, given the small market, leaving governments to fund the bulk of research.

After Brantly and Writebol were infected in Liberia, they received doses of an experimental serum known as ZMapp, a cocktail of antibodies meant to fight off the disease, which was flown from the United States expressly for them.

The Americans, who were in grave condition, improved noticeably after receiving ZMapp, according to some reports and statements from the Christian relief groups associated with the missionaries. It remains unclear, however, how much of that progress was attributable to the drug.

Only a handful of doses of ZMapp exist, though the companies that produce it have said they are working with government agencies to ramp up production. Still, it probably would take months to manufacture enough of the cocktail of antibodies to distribute widely in West Africa.

“We weren’t anticipating testing the drug in humans until safety trials in 2015,” Larry Zeitlin, the co-founder of Mapp Biopharmaceutical, which developed ZMapp, said in an e-mail Wednesday. “As such, our manufacturing partner, [Kentucky BioProcessing], only produced the amount needed for testing safety and efficacy in animals. This explains why so little is available.”

Meanwhile, a Massachusetts biotech firm, Sarepta, said Wednesday that it had notified various government agencies about supplies of an Ebola treatment it has on hand. The company, better known for its development of a promising drug for Duchenne muscular dystrophy, began working on an Ebola drug a decade ago after a government researcher in Maryland accidentally pricked herself with an Ebola-contaminated needle.

As the worst Ebola outbreak in history unfolds in West Africa, the Post's Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)

Sarepta quickly worked to develop an emergency treatment, said Diane Berry, the company’s vice president for global health policy and government affairs. The scientist was not infected, but the episode led to a partnership between the government and Sarepta.

In 2010, the company received a contract for nearly $300 million to develop treatments for Ebola and Marburg, a similar virus. In 2012, fiscal fights on Capitol Hill resulted in budget cuts that shelved the project. Sarepta had done nonhuman-primate studies with its drug, which is intended to prevent the virus’s spread within the body. Sixty to 80 percent of the primates survived. The company also did a small study in humans to make sure the drug had no safety issues.

Sarepta said it has enough of the medication on hand to treat a couple of dozen patients. It has enough raw materials to produce treatments for an additional 100 people, but even that would take a couple months, Berry said.

The WHO does not approve medicines and is not a regulatory agency. But it does set standards, and often provides guidance when a public health emergency arises. Agency officials said Wednesday that the WHO plans to convene the medical ethicists Monday or Tuesday and hopes to move as quickly as possible given the urgent nature of the crisis in West Africa.

Also Wednesday, the Food and Drug Administration said it had issued an emergency authorization for the use of an in vitro diagnostic test developed by the Defense Department to help detect the strain of the Ebola virus ravaging West Africa. The test is designed for use in individuals, including medical personnel, who may have been exposed to the virus.

The WHO and FDA actions Wednesday underscored the urgency of the worsening situation in West Africa, where Ebola continues to spread in four countries: Liberia, Nigeria, Guinea and Sierra Leone. The WHO reported Wednesday that the death toll from the outbreak had risen to 932, with more than 1,711 total cases.