NEW YORK — Two American aid workers infected with Ebola are getting an experimental drug so novel it has never been tested for safety in humans.
The drug, ZMapp, was identified as a potential treatment earlier this year, thanks to a longstanding research program by the US government and the military.
The workers, Nancy Writebol and Dr. Kent Brantly, are improving, although it is impossible to know whether the treatment is the reason or they are recovering on their own, as others who have survived Ebola have done.
Brantly is being treated at a special isolation unit at Atlanta’s Emory University Hospital, and Writebol left Liberia for Atlanta early Tuesday, flown in the same specially equipped plane that brought Brantly.
They were infected while working in Liberia, one of four West African nations dealing with the world’s largest Ebola outbreak. On Monday, the World Health Organization said the death toll had increased from 729 to 887 in Guinea, Sierra Leone, Liberia, and Nigeria, and that more than 1,600 people have been infected.
A New York City hospital said Monday that it is performing Ebola tests on a patient who recently traveled to West Africa. Mount Sinai Medical Center said the male patient came in Monday with a high fever and gastrointestinal symptoms. He was placed in strict isolation and was undergoing medical screenings.
But the city health department issued a statement late Monday saying that after consulting with Mount Sinai and the Centers for Disease Control and Prevention in Atlanta, “the health department has concluded that the patient is unlikely to have Ebola.’’
ZMapp is aimed at boosting the immune system’s efforts to fight off Ebola and is made from antibodies produced by lab animals exposed to parts of the virus.
The New York Times reported that the case was one of three at metro New York hospitals in which doctors, their awareness heightened by the West Africa crisis, have ordered additional testing and precautionary isolation for patients.
Officials at US international airports are watching travelers from Africa for flu-like symptoms that could be tied to Ebola.
In a worrisome development, the Nigerian Health Minister said Monday that a doctor who had helped treat Patrick Sawyer, the Liberian-American man who died July 25, days after arriving in Nigeria, has been confirmed to have the deadly disease. Tests are pending in Nigeria for three other people who also treated Sawyer and are showing symptoms.
There is no vaccine or specific treatment for Ebola but several are under development. The disease starts with symptoms resembling the flu and can progress to severe hemorrhaging.
The experimental treatment the US aid workers are getting is made by Mapp Biopharmaceutical Inc. of San Diego. It is aimed at boosting the immune system’s efforts to fight off Ebola and is made from antibodies produced by lab animals exposed to parts of the virus.
The company said it is working with LeafBio of San Diego, Defyrus Inc. of Toronto, the US government, and the Public Health Agency of Canada on development and production of the drug.
The Food and Drug Administration must grant permission to use experimental treatments in the United States, but the FDA does not have authority over the use of such a drug in other countries, and the aid workers were first treated in Liberia. An FDA spokeswoman said she could not confirm or deny the FDA granting access to any experimental therapy for the aid workers while in the United States.
Writebol, 59, had been in isolation at her home in Liberia before leaving for Atlanta. She is now walking with assistance and has regained her appetite, said Bruce Johnson, president of SIM USA, based in Charlotte, N.C. Writebol, who works for SIM, received two doses of the experimental drug while in Liberia.
Johnson was hesitant to credit the treatment for her improvement. “One day is not indicative of the outcome,’’ he said. But ‘‘we’re grateful this medicine was available.’’
Brantly, 33, who works for the international relief group Samaritan’s Purse of Boone, N.C., also was said to be improving. Besides the experimental dose he got in Liberia, he also received a unit of blood from a 14-year-old boy, an Ebola survivor, who had been under his care. That seems to be aimed at giving Brantly antibodies the boy may have made to the virus.
Ebola is only spread through direct contact with an infected person’s blood or other bodily fluids, not through the air.
The Defense Department has long had a hand in researching infectious diseases, including Ebola. The US military does research related to infectious diseases as a means of staying current on potential threats to the health of troops. It may also contribute medical expertise as part of interagency efforts in such places as Africa, where infectious disease threats arise.