WASHINGTON, September 30, 2014 — The first case of Ebola to be diagnosed on American soil was confirmed today by the Centers for Disease Control. Based on his travel history and symptoms, the patient was placed in intensive-care isolation in the Texas Health Presbyterian Hospital in Dallas.
According to Thomas Frieden, the director of the CDC, the patient returned to the United States from Liberia on September 19. He began showing symptoms of illness on September 24, and went for medical treatment on the 26th. He was admitted to the hospital on September 28.
Ebola is contagious only once symptoms appear. The virus is spread in body fluids and wastes: sweat, blood, tears, vomit, and diarrhea. It typically has an incubation period of 10 to 20 days, so a patient infected in Liberia might not show symptoms for almost three weeks after arrival in the U.S.
The Dallas patient would have been contagious for four days before entering the hospital. However, CDC officials are confident that even if the patient infected someone else, the infection can be quickly contained. The man’s contacts are being traced. If they have been infected, and if they can be isolated before they develop symptoms, then there will be no outbreak in the U.S.
Because the man was asymptomatic until he’d been in the U.S. for five days, there is almost no chance that he infected anyone else on the airplane. The stringent isolation procedures that can be implemented in American hospitals make the likelihood of spread from the hospital isolation unit likewise extremely remote.
The current epidemic in Africa has become catastrophic because of a near perfect combination of poor medical services, recent civil war, widespread distrust of government, and crowded, unsanitary urban conditions that have frustrated efforts to treat the disease and get full public cooperation in the efforts to stop its spread. The epidemic has so far produced over 6,500 confirmed Ebola infections, and over 3,000 deaths.
The Ebola virus is one member of a family of viruses called “filoviruses” that cause hemorrhagic fevers. These viruses are responsible for illnesses ranging from yellow fever and Hanta fever in the Americas to Ebola and Marburg fevers in Africa. They are long, filamentous viruses.
There is currently no proven vaccine to prevent Ebola infection or disease, though work has been accelerated on experimental vaccines and treatments. These include a DNA vaccine, which unlike traditional vaccines that involve injecting dead or attenuated virus into a healthy person to cause an immune response, involve injecting bits of DNA that will result in production of viral proteins in the host. These proteins then elicit the immune response.
Potential vaccines must be shown to be both safe and effective. At least one experimental Ebola vaccine has been demonstrated to be safe — it caused no ill effects in healthy volunteers — but it has not been shown to be effective. Because of the dire state of health care in the affected areas and the grim forecasts for the course of the epidemic, the World Health Organization (WHO) is considering something unprecedented: widespread use of a vaccine that has not been shown to be effective.
If WHO decides to pursue that strategy, volunteers among the care givers in the affected region would be the first vaccinated.
Supplies of the experimental treatment ZMapp, a synthetic antibody to the Ebola virus, have been completely depleted by the African epidemic. Other drugs, like TKM-Ebola, are, like ZMapp, not known with certainty to be effective.
The western patients who received these treatments have survived, but it isn’t known whether that is because the treatments are effective, or because the patients have received excellent care to keep them hydrated and stop hemorrhaging.
To determine whether a vaccine or treatment is effective, researchers would provide the actual medication to a large group of people, and a placebo to another, control group. They would then observe whether there was a lower rate of infection or better rate of survival in the group that received the real medication.
In the conditions facing workers in Africa, WHO may be prepared to discard that approach. Dr. Anthony Fauci of America’s National Institutes for Health (NIH) believes that would be a huge mistake. “If you did it in the way where you never could tell whether it worked well, worked a little, didn’t work at all, or actually made people worse … you could actually propagate a disaster.”
That point is underlined by recent work on an HIV vaccine. Initial trials indicated that the vaccine was safe. Further testing showed that it increased the likelihood of HIV infection.
WHO is expected to announce its decision on whether to move forward with use of untested vaccines tomorrow.