Ebola Is Rapidly Mutating As It Spreads Across West Africa
DAVID GREENE, HOST:
We have a story this morning of knowledge that was extremely dangerous to gather, but the knowledge was so important that people were willing to die to get it. It's information about the spread of Ebola in western Africa. Thanks to the perilous work of researchers, scientists for the first time have been able to follow the spread of the virus by sequencing its genetic makeup from people in west Africa. These findings offer new insights into how the outbreak started and how quickly the virus is mutating. NPR's Michaeleen Doucleff reports.
MICHAELEEN DOUCLEFF, BYLINE: Ebola is one of the deadliest viruses on earth and yet it has just seven genes. We humans have about 20,000 genes.
PARDIS SABETI: Within a genome so small, there's a lot of things packed into a very short sequence that's - that are doing this extraordinary amount of damage.
DOUCLEFF: That's Pardis Sabeti. She studies genetics at Harvard. She says that hidden inside Ebola's tiny little genome are clues to how people catch the virus and how to stop it.
SABETI: So as soon as the outbreak happened and was reported in Guinea, two members of my lab flew out and worked to set up the diagnostics to pick it up in Sierra Leone.
DOUCLEFF: That was back in April. Her team helped to find the first 100 or so Ebola cases in Sierra Leone. During the process, several people on the project caught Ebola; five of them died.
SABETI: The work is just that dangerous. Another British nurse at the hospital has just come down with Ebola, and you're seeing so many infections going on right now. And it is an extraordinary thing that is going on right now.
DOUCLEFF: Health workers who NPR talked to back in the spring, they blame a lack of proper protective equipment at government-run hospitals. Sabeti said she wanted to do more than just diagnose Ebola; she wanted to help stop the outbreak. So her team shipped samples back to Boston, and they started sequencing the virus's genome from patients all over Sierra Leone.
SABETI: We had 20 people in my lab working around the clock.
DOUCLEFF: The furious work paid off; after just a week or so, the team had decoded gene sequences from 99 Ebola samples. They just published the data in the journal Science, and the findings offer a treasure trove of information about the outbreak. For starters, the data show that the outbreak started when just one person caught Ebola from animal. Then the virus has been spreading only through people; it's not coming from bush meat or wild game as first thought.
SABETI: We were really concerned 'cause a lot of the messaging that's going out around those populations is, don't eat bush meat, don't eat mangoes, don't eat anything that might be in contact with animals. And when you see some of those flyers, by the end you're like, OK, you just actually told them not to eat all of their main sources of food.
DOUCLEFF: So the advice from health officials to avoid bush meat may be doing more harm than good. The data also show that the virus is rapidly picking up new mutations as it spreads through people.
SABETI: And so we found over, you know, 250 mutations that are just changing as - in sort of real-time as we're watching.
DOUCLEFF: That's about twice as fast as the virus had been mutating while circulating in bats for the last decade or so. Sabeti thinks that might be a cause for concern.
SABETI: The more time you give a virus to mutate and the more opportunities of human-to-human transmission you see, the more opportunities it's going to fall upon something that could make it more easily transmissible or pathogenic.
DOUCLEFF: Sabeti said she doesn't know if that's happening yet. Stephen Morse is a virologist at Columbia University. He says that this study is a technical feat.
STEPHEN MORSE: It really is a tour de force in that they were able to sequence 99 genomes. And that's really quite remarkable in this timeframe.
DOUCLEFF: But he's not surprised the virus is mutating so rapidly.
MORSE: We've seen it in a number of other infections, SARS for example, Influenza, HIV of course. Very often when a new virus is introduced into the human population, very suddenly it will show accelerated rates of evolution.
DOUCLEFF: So should we be concerned that the virus might pick up a mutation that makes it more contagious or deadly?
MORSE: That's very hard to say. In most cases, the answer would probably be no.
DOUCLEFF: But at this stage, he says, we just don't have enough information yet to say exactly what the future of this outbreak will be. Michaeleen Doucleff, NPR News.
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