By Richard Preston
August 7, 2019
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.
Ebola virus is a microscopic parasite that replicates inside the cells of a host. The outbreak in eastern Congo began more than a year ago, in or near a town called Mangina, when a few particles of Ebola virus apparently moved out of some wild creature, Ebola’s natural host—in this case, probably a bat—and entered the bloodstream of an as yet unidentified person. From that person, the virus began spreading through the local population. Ebola can overwhelm the human immune system in a matter of days. Symptoms typically include vomiting, diarrhea, coughing, rash, dementia, hemorrhages, and hiccups. Death occurs like the slamming of a door, when the patient abruptly goes into shock.
The Kivu Ebola outbreak area is in a conflict zone, beset by armed militias and ethnic violence. Local people often don’t trust the international medical organizations that run the Ebola treatment centers. There have been at least a hundred and ninety-four attacks on local health workers, seven of whom have been killed. Watson-Stryker, the researcher, said that social media complicates containment and treatment efforts. Conspiracy theories about medical workers and false information about how the virus is spread are ricocheting around popular platforms like WhatsApp. “The problem is the post-factual reality that exists in social media,” she said.
An effective experimental vaccine for Ebola exists, and more than a hundred and seventy-five thousand people have received it. Even so, the virus is finding new victims and extending its geographic range. Three cases of Ebola recently appeared in Uganda, and there have now been four cases in the Congolese city of Goma, which has roughly two million residents and is situated on the border with Rwanda. The W.H.O. recently estimated that more than two hundred million dollars in emergency funding would be needed to bring the virus under control. That money hasn’t been raised yet.
An Ebola particle is a very small, filament-shaped object, made of six different structural proteins. Ebola’s genetic code, or genome, is contained in a strand of ribonucleic acid, or RNA, that is coiled tightly in the core of the particle. The genome, which has some nineteen thousand letters in it, holds the master designs of Ebola’s proteins.
RNA viruses—which range from Ebola to measles and influenza— tend to produce errors, or mutations, in their code when they copy themselves. Most mutations are either bad for the virus or have no effect on it. Every now and then, however, a virus gets a mutation that benefits it. In fact, the production of errors during copying plays an important role in the long-term survival of viruses. As time goes by and the virus makes inaccurate copies of itself, slightly different varieties of the virus arise. The different varieties are called lineages. They can be imagined as moths of the same species whose wings are slightly different colors. Some wing colors help a moth camouflage itself more effectively, be eaten less often by predators, and survive longer than moths of other colors. Those types of moths go on to reproduce successfully, while moths of other colors eventually die out, until the population of moths has changed color entirely. This is the process of evolution.