Ebola: The Natural and Human History of a Deadly Virus

Ebola is a rude guest. You, on the other hand, are a poor host. Ebola arrives uninvited and unannounced, it is true, like a roadside bomb. You, as usual, are woefully unprepared for this eventuality. It isn’t as though Ebola hasn’t done this before. Remember Zaire in 1976 and Kenya in ’77, the upper Ivindo River in ’94 and Zaire again in ’95, Gabon in ’96 and the Congo in ’01, ’02, and ’05, and the other Congo in ’07, and now — ’14 and beyond — all over West Africa? When are you going to learn to be ready?

Ebola is “rivetingly awful,” writes David Quammen in Ebola, a disease that kills an alarming percentage of the animals it infects — animals like humans, though many others, too — typically in the 50–90 percent range. But by dying, we throw a wrench into Ebola’s designs to survive and reproduce. Most of the time. Our dead bodies, if handled with the utmost care, spell the end of that particular viral population. If not handled properly, our bodies are excellent vehicles of transmission. Then our standing as a host gets reconsidered.

Two years ago, Quammen wrote a book entitled Spillover, which made the case for coming pandemics — most likely from newly loosed viral agents such as Ebola — being on a par with, or worse than, the Black Plague and influenza. It was reviewed here. If for whatever unforgivable reason you did not read Spillover, then for Pete’s sake read Ebola, which uses Spillover as a launching pad, but enriched with new material and made as current as a publication date allows. It is concise, eerily musical for its topic — Ebola takes center stage — and, unfortunately, topical.

It is Quammen’s gift to let biological processes make joyful noise. Like zoonosis: “Everything comes from somewhere, and strange new infectious diseases, emerging abruptly among humans, come mostly from nonhuman animals.” And spillover: when the reservoir host animal generously shares the virus it houses — having reached some accommodation so that the virus doesn’t kill it — with another animal, which can become an intermediate (and probably short-lived) host passing the virus along to, say, humans. An important distinction: Ebola is not very contagious, but it is wickedly infectious —  a teeny particle will do. Maybe an Egyptian fruit bat, the host, nibbles on some fruit. A chimp then eats that fruit, along with the bat’s teemingly viral saliva. The chimp dies. Bush meat — standard fare on remote village tables when other food supplies are scarce, its invisible cargo as lethal as botulism in a bloated can of Spam. Moral: don’t eat bloated cans of Spam or creatures lying dead on the forest floor. The reservoir (or reservoirs) of Ebola, I should add, has yet to be firmly identified.

Like Ebola virus disease, to give it its proper name — and not Ebola hemorrhagic fever, as it was once known, since not all victims “bleed out,” as Richard Preston unforgettably described the disease’s effects in The Hot Zone — humans are masters of disruption, which may be why Africa is a conspicuous nursery for emerging viruses. The continent’s high biological diversity and (relatively) undisturbed landscape is ripe to release a storehouse of unknowns, among them pathogens, when humans encroach, or cause other animals to encroach, upon their habitat. Humans are doing just that in such environments. So it goes in the Philippines, in Australia, in India, in China, in South America, wherever the conditions allow. The consequent outbreaks to date include Marburg virus, hantavirus, Lassa fever, Sudan and Taï Forest viruses, Nipah, Crimean-Congo hemorrhagic fever, Chikungunya, Ebola, and its cousin strains, not to forget our old friends yellow fever and rabies, the latter killing 100 percent of those who don’t get treatment before the symptoms emerge.

Quammen humbly claims this work is a partial view of the history and science of Ebola. That is so, yet it has the potential to vastly raise our awareness of new, ferocious viruses. Quammen provides the fundamentals — ecology, evolutionary history, natural cycles — of what we know about viruses, from the big picture to the various species. A great deal is unknown about the emerging viruses, but viruses in general aren’t new to science. They are small and simple. They must abide in a living creature to get on with their Darwinian business. Their genomes are single strands of RNA, which — because they commit more mistakes during replication than the double-helix DNA — makes them highly mutable and very adaptable. Sometimes the newly minted RNA code can adapt to its new host — a new reservoir — with each spillover a random opportunity.

Not to give bats a bad name — they can be our boon companions, eating mosquitoes by the peck and drove and pollinating with abandon — but one in four mammals is a bat. They have an old lineage, roost in close contact and big numbers, and include thousands of species, so they have become “persons of interest” to researchers. Quammen describes what these scientists do to connect the epidemiological dots. They don Tyvek suits and respirators in the equatorial heat, crawl into caves where uncountable bats with two-foot wingspans and viciously sharp thumbnails hang from the ceiling and the floor is a shag carpet of slimy guano — maybe abounding with Ebola or Crimean-Congo — creep deeper and deeper into dark shafts and chambers where the nervous, death-dealing black forest cobra resides, to look for dead bats overflowing with bloody-minded viruses. It is probable that the scientists are out there right now. Imagine that synchronicity. Raise a glass to what surely deserves to be called heroic.

The World Health Organization declared the recent and ongoing Ebola outbreak in West Africa a Public Health Emergency of International Concern (a.k.a. PHEIC, for the acronym-happy). There have been more cases and fatalities than in all prior Ebola outbreaks combined. “What we should recognize, what we should remember,” writes Quammen, “is that the events in West Africa (so far) tell us not just about the ugly facts of Ebola’s transmissibility and lethality; they tell us also about the ugly facts of poverty, inadequate health care, political dysfunction, and desperation in three West African countries, and the neglectful disregard of those circumstances over time by the international community.”

Ebola isn’t malicious, because Ebola harbors no sentiments. Still,  it can’t help but find in conditions like these an excellent invitation to make itself, disastrously, at home.

Comments are closed.