The Ebola strain behind the most recent epidemic doesn’t appear to be much different from other strains which caused previous outbreaks. That’s not great news—it’s still Ebola, after all, and it’s still deadly—but it’s not bad news either. The virus doesn’t seem to be any more lethal or more transmissible.
And in a way, that shouldn’t be surprising. The random mutations that drive evolution could lead to a more deadly strain, or they could just as easily lead to a milder strain. The fear with Ebola is that, because the disease is already so deadly, that any change to its mode of transmission would could be devastating. Currently, the virus is transmitted through bodily fluids. But if a mutation allows it to be communicated through the air, we’d be in a much graver situation.
Fortunately, that’s not what scientists found. Here’s Pam Belluck, reporting for the New York Times:
Essentially, the study indicates, while this outbreak has infected 24,000 people and killed about 10,000, its scale has to do with where the epidemic erupted — at the intersection of three vulnerable countries — rather than with any unusual characteristics of the virus itself.
The scientists evaluated change in the virus over time by comparing genetic sequencing data from a small number of cases in Mali in October and November with data from patients infected in Guinea in March 2014 andSierra Leone in June .
They found that the number of mutations was about the same as in viruses in previous outbreaks, suggesting that the virus was not mutating faster. And they reported that the genetic changes they identified were not significant enough to make the virus more transmissible or deadlier.
Since Ebola doesn’t rely on an intermediary like a mosquito to be transmitted, a theory posited by evolutionary biologist Paul Ewald says that human-to-human transmitted viruses tend to evolve toward mildness . Look no further than the rhino virus, which causes the common cold. By allowing us to be moderately functional while infected, it can be easily transmitted to many new hosts. Ebola may be no different , though there’s still the chance that a mutation could imbue it with a frightening combination of properties, so it’s best to be cautious.
The real concern over Ebola’s mutation rate stems from the fact that the tools we use to detect and treat it are tailored for the current strain’s genetic code. If that code changes too quickly, we may miss critical cases. It could also wipe out the progress we’ve made on developing a vaccine, which is our best hope for containing future outbreaks of this and other closely related strains.