The following editorial appears in the September issue of Nature Medicine.
The size, speed and potential reach of the 2014 Ebola virus outbreak in West Africa presents a wake-up call to the research and pharmaceutical communities—and to federal governments—of the continuing need to invest resources in the study and cure of emerging infectious diseases.
At the time of this writing, more than 2,200 people are estimated to have been infected by a new strain of Zaire ebolavirus in four West African nations, and more than 1,200 have died. Infection can cause fever, vomiting, diarrhea and internal and external hemorrhaging that can lead to death. Neighboring as well as non-neighboring countries are at risk because of porous borders and air travel of presymptomatic infected individuals, the latter having resulted in the spread of infection to Nigeria. And while the death rate—estimated at 55%—is lower than that of many previous Ebola outbreaks, the total number of cases exceeds all ebolavirus infections since 1976. We don’t know when the outbreak will end, or how far it will spread, but its control is expected to take months and may involve extraordinary measures.
Ebola virus first emerged in the Democratic Republic of the Congo (DRC) and in South Sudan in 1976 and reappeared in South Sudan in 1979, but it caused no further outbreaks until 1994. Since then, there have been several outbreaks in Africa, but none approached the magnitude of the current outbreak. The natural reservoir of the virus remains unclear, but it is suspected to be the fruit bat. However, Ebola virus also infects nonhuman primates, a species of antelope and porcupines, all of which could be sources of human transmission.
The unusually rapid and far-reaching spread of the virus during the current outbreak has been facilitated by insufficient treatment and containment facilities in West African nations that had no prior experience with Ebola; a distrust of Western medical practices; the stigma associated with infection, causing failure to seek early treatment; as well as the long asymptomatic incubation period of the virus (up to 21 days), which enables dissemination through travel.