Is Ebola Evolving Into a More Deadly Virus?

This July, the World Health Organization declared that an outbreak of Ebola in the provinces of Ituri and North-Kivu, in the eastern Democratic Republic of the Congo, was a “public health emergency of international concern.” This particular strain of the virus, which first appeared in the region in 2018 and hasn't been given a formal name—I'll call it Kivu Ebola—is a variant of a species known as the Zaire Ebola virus. As of last Saturday, 2,753 cases of Kivu Ebola have been reported, with 1,843 deaths. There appear to be many undiscovered cases in the region, too. Ella Watson-Stryker, a social scientist with Doctors Without Borders, who has been studying the outbreak, said that around half of all Ebola patients admitted to treatment centers in eastern Congo aren't part of any known chain of transmission. In other words, the infected person has caught Ebola from somebody whom disease investigators haven't yet identified. “A lot of transmission is not being seen, but nobody knows the exact amount,” Watson-Stryker told me.