Nebraska patient case raises questions about Ebola test

The death of physician Martin Salia from Ebola has raised questions about the tests and drugs used in the disease.

Salia, a surgeon who was flown from Sierra Leone to Omaha's Nebraska Medical Center Saturday, had two negative tests for Ebola before testing positive. He arrived in Omaha on the thirteenth day of his illness, said Phil Smith, medical director of the Nebraska hospital's biocontainment unit, one of four around the USA designed for the most dangerous infectious diseases.

Salia is the 10th person with Ebola treated in the USA. While all eight Americans have survived, both patients from Africa -- including Liberian national Thomas Eric Duncan -- have died.

Although Ebola tests are generally considered accurate, they may produce false negative results early in a person's infection, when levels of the virus are still low, says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. The test isn't sensitive enough to detect very small amounts of virus.

That's why people who suspect they could have Ebola -- because they have symptoms and may have been exposed to the virus -- should be retested again in 48 to 72 hours, Fauci says.

Guidelines from Doctors Without Borders note that, "false negative results can occur in the first three days of symptoms when the viral load is low. If the disease is suspected and the result is negative, the test needs to be repeated on or after the fourth day of symptoms."

Fauci says false negative results don't pose a major public health risk. That's because people with low levels of virus aren't very contagious. People generally become more contagious as the level of virus rises, later in the illness. That puts hospital workers at greater risk than the average person in the community.

Even a patient who has begun to feel sick is not likely to spread the disease to others until the patient begins to lose bodily fluids, such as through blood, vomit and diarrhea, Fauci says.

In addition to supportive care in the intensive care unit, Salia received two experimental therapies -- a blood donation from someone who survived Ebola and the drug ZMapp. Hospital officials declined to reveal which Ebola survivor provided the blood.

Salia is the first Ebola patient to receive ZMapp in the USA since August, when the drug was given to physician Kent Brantly and missionary Nancy Writebol. A handful of Ebola patients in other countries also received the drug, which isn't yet approved.

An Aug. 12 statement on the web site of ZMapp's maker, Mapp Biopharmaceutical of San Diego, says that supplies of the drug have been exhausted. The drug takes several months to produce, using tobacco plants.

But when the hospital contacted Mapp Biopharmaceutical, the company was able to send a dose, said Chris Kratochvil, the associate vice chair for clinical research at the University of Nebraska Medical Center.

"We don't have any recognized supplies of ZMapp," Fauci said. "It's obvious that somewhere, somehow, people have a dose or two stowed away. When people get it, I'm not sure where they get it from."

Nebraska doctors said they used a variety of therapies to try to save Salia, who was unresponsive and in kidney failure and respiratory failure when he arrived Saturday. Those methods included kidney dialysis and a breathing machine. Doctors gave him two powerful drugs to raise his blood pressure, which was collapsing.

Those efforts came too late in Salia's illness. He died 36 hours of cardiac arrest after arriving in Omaha.

"The earlier you start supportive care, the better," Smith said.

Thomas Geisbert, a professor of microbiology and immunology at the University of Texas Medical Branch, has researched experimental Ebola therapies in animals for years. When getting therapy to people infected with the disease, "every day matters; every hour matters," he says.

Ebola has killed more than 5,000 people, largely in Sierra Leone, Liberia and Guinea.

A separate Ebola outbreak in the Democratic Republic of Congo, which began in August and is unrelated to the West African outbreak, is now under control. There have been no new cases since Oct. 4, according to Doctors Without Borders.