UC San Francisco researchers who are studying strains from five previous Ebola virus outbreaks in central Africa are hoping to receive samples from the current strain to better understand what has reportedly become the deadliest outbreak of the virus.
Dr. Charles Chiu, an assistant professor in laboratory medicine and infectious diseases who specializes in infectious disease diagnostics, has been in touch with collaborators in West Africa, where more than 800 people are believed to have died from the virus as of Friday, in an effort to acquire noninfectious samples of the strain.
Chiu, along with a team of 12 UCSF researchers, is hoping to study the current strain circulating in Guinea, Sierra Leone and Liberia -- which is Zaire, the deadliest of the five Ebola strains with a mortality rate of 50 to 90 percent. They intend to learn whether it is an offshoot of prior outbreaks or an independent introduction from an animal source in nature, thought to be the fruit bat.
"We're hoping to get samples from different locations, from different host sites, within different countries, and at different times, to find out what's going on," Chiu said.
The team's work would come as an American doctor and an aide who recently contracted the virus while working in West Africa have been transported to Atlanta for treatment at an Emory University hospital.
Chiu and the researchers plan to sequence many viruses from Ebola cases and compare them to the Ebola sequences from outbreaks in central Africa to examine how the virus mutates, and to compare differences between viral sequences obtained from different geographic locales.
"That's important because this will help us provide some insight into how do these outbreaks emerge," Chiu explained. "Is it being transmitted from person to person, or is it really due to the fact that we're right at the animal-human interface in Africa, where there's a lot of contact with the animal reservoir that harbors the virus?"
Understanding the virus' mutation could help in the design of more sensitive and accurate diagnostic tests for the Ebola virus in the field, provide clues as to the origin of the virus, and help to understand whether and how the virus is changing over time, researchers note.
The five previous outbreaks Chiu is currently studying, which occurred in central Africa from 1995 to 2007, are all from the Zaire strain as well and are "all very similar to each other, but they're not 100 percent identical," Chiu said.
It's unknown whether the current outbreak is a manifestation of the same Zaire strain that was discovered in 1976, said Chiu. But it's also possible that the disease is a new introduction, which is Chiu's prediction.
"If I had to guess, I'd say these are most likely independent introductions," Chiu said.As of Aug. 1, the World Health Organization has reported 887 deaths believed to be linked to the Ebola virus in Guinea, Liberia, Nigeria and Sierra Leone, and 574 confirmed deaths. A cumulative 1,603 cases attributed to the disease have been recorded, of which 1,009 are confirmed.