The use of an experimental drug to treat two Americans diagnosed with Ebola is raising ethical questions about who gets first access to unproven new therapies for the deadly disease. Some health experts fear debate over extremely limited doses will distract from tried-and-true measures to curb the growing outbreak, things such as more rapidly identifying and isolating the sick.

The World Health Organization (WHO) is convening a meeting of medical ethicists next week to examine what it calls “the responsible thing to do” about whatever supplies eventually may become available of a medicine that’s never been tested in people.

At least one country involved in the outbreak is interested in the drug. Nigeria’s health minister, Onyenbuchi Chukwu, said at a news conference that he had asked the U.S. Centers for Disease Control and Prevention (CDC) about access. CDC Director Tom Frieden “conveyed there are virtually no doses available” but that basic supportive care can work, a CDC spokesman said Wednesday.

Patient advocates who believe the drug — ZMapp, which is made by a San Diego drug company and which has shown promise in monkeys — is helpful are asking when it can be made available to hundreds of West Africans who are ill.

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But what looks like a simple case of humanitarian goodwill could lead to some unintended and negative consequences, experts said.

Although there could be a short-term gain for a dying patient, in the long run it would undermine scientists’ ability to determine whether the drug was safe and effective.

“I don’t think we want to say these drug companies are obligated to suddenly mass-produce these drugs,” said Jennifer Blumenthal-Barby, a medical ethicist at Baylor College of Medicine in Houston. “That would subvert the whole FDA-regulated process of trying to do solid research on these drugs.”

The Food and Drug Administration (FDA) has elaborate rules for evaluating drugs before they are approved for widespread use. The process can take years, involving hundreds or thousands of patients and costing drug companies millions of dollars.

The rules are designed to make sure that a medication doesn’t make patients more sick than they are and that it fights the disease it was created to fight. They are also used to figure out the minimum dose needed to get the desired effect.

The centerpiece of these rules is the clinical trial, which allows researchers to show that patients who took the drug fared better than patients who didn’t.

In this case, there will be no way to tell whether Dr. Kent Brantly and hygienist Nancy Writebol were helped by the experimental Ebola drug, said Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases.

The two aid workers are being treated in a specialized isolation ward at Emory University Hospital in Atlanta. If they survive their infections, doctors won’t know whether it’s because of the drug or the other care they receive. The only thing they’ll be able to say with certainty is that the drug didn’t kill them.

“I do hope that it was effective, but when you’re dealing with medicine and all the vicissitudes, you can’t say definitively,” Fauci said.

Ebola is a virus that causes flulike symptoms, such as fever, vomiting, aches and intense weakness. As it progresses, patients may suffer serious bleeding and kidney or liver failure.

Experts estimate it is fatal in 45 percent to 90 percent of cases. In the current outbreak, at least 932 deaths in four countries have been blamed on the illness, with 1,711 reported cases, according to WHO.

ZMapp, the drug given to Brantly and Writebol, is a cocktail of three monoclonal antibodies designed to prevent the Ebola virus from latching on to and inserting itself into a host cell. If the virus does enter the cell, it begins to mass-produce copies of itself. Using modern techniques to fight Ebola, scientists culled antibodies from laboratory mice, Fauci said, and ZMapp’s maker now grows the antibodies in tobacco plants and then purifies them.

Fauci said the manufacturer has told the government it would take two to three months to produce even “a modest amount.” So the National Institutes of Health (NIH) is exploring ways to ramp up production, necessary to attempt formal testing or to consider more so-called compassionate use.

ZMapp is one of several under development to fight Ebola. Allowing any of them to be given to patients without proper vetting would be problematic, said Arthur Caplan, director of the medical-ethics division at the New York University Langone Medical Center.

“There’s a fairly good chance that it could do more harm than good,” Caplan said. “The drug could kill you faster, or make you die more miserably.”

Ebola isn’t 100 percent fatal, he said; some patients who might have survived could wind up dying after taking an untested drug.

Even if it seems that patients have nothing to lose, the FDA has argued that its clinical-trial system ultimately benefits more patients.

There are other problems. Monoclonal antibody drugs such as ZMapp are expensive to produce, so determining the smallest dose that’s still effective is important, Caplan said. That requires proper testing.

To help improve diagnosis in affected countries, the FDA on Wednesday authorized emergency use of an experimental blood test to detect Ebola. Early symptoms can be confused with other illnesses. The test was developed by the Defense Department and is only for use in DOD-designated laboratories.