Ifor Williams, MD, PhD

Ifor Williams, MD, PhD

The Ebola virus disease outbreak of 2014 centered in West Africa is the most extensive outbreak yet of this viral hemorrhagic fever with a high mortality rate (60-90% in most previous outbreaks). On August 8, the WHO declared the 2014 outbreak to be a Public Health Emergency of International Concern.

The unprecedented 2014 Ebola outbreak has sparked intensive media coverage. One focus of media attention is the saga of 2 American aid workers infected with Ebola in Liberia, treated while in Liberia with an experimental antibody-based treatment called ZMapp, and then flown to the U.S. in early August for continued care in a special isolation unit at Emory University Hospital in Atlanta designed with the help of the CDC. At the time of submission of this story, the first 2 Ebola-infected patients treated in the U.S. were still being cared for in Emory’s isolation unit.

The ZMapp antibody treatment the 2 Americans received is a combination of 3 human monoclonal antibodies targeting Ebola virus proteins. The antibodies are expressed in tobacco plants and then purified for administration. Mapp Pharmaceutical, the producers of ZMapp, had previously done limited preclinical testing of ZMapp in rhesus macaques recently infected with Ebola virus with promising results showing reduced mortality. But the drug had never been tested in even early stage human clinical trials, making its administration to the 2 Americans an extraordinary event. While anecdotal information reported about the male physician who received ZMapp suggests that some symptoms abated rapidly after his initial infusion, few if any conclusions can be drawn about the effectiveness of ZMapp based on its compassionate use.

Because ZMapp supplies are extremely limited, very few additional Ebola patients will receive this treatment in this year’s outbreak. On August 11, an Ebola-infected Spanish priest was reported to be the third recipient of ZMapp. Another drug that may be given to humans during this year’s outbreak is TKM-Ebola being developed by Tekmira Pharmaceutical; TKM-Ebola is an RNA interference (RNAi) therapeutic.

The 2014 Ebola outbreak will spur expanded interest in the development of drugs to treat Ebola as well as vaccines to limit the spread of future outbreaks and protect health care workers on the frontlines. Since mucosal surfaces are likely to be the initial sites of exposure to virus in body fluids from infected patients, vaccine products that can confer robust protective mucosal immunity may be especially valuable.