EBOLA
The Natural and Human History of a Deadly Virus
David Quammen
W W Norton & Company; 119 pages; $13.95
Ebola has come to be described in horror-movie terms as an affliction, in the words of the journalist David Quammen, that "seems to kill like the 10th plague of Egypt in Exodus - the one inflicted by an angel of death". With a mortality rate as high as 90 per cent, it kills painfully and swiftly, with a seemingly remorseless calculus. There is even an article on the website of the Centers for Disease Control and Prevention that compares Ebola to the ghastly scourge in "The Masque of the Red Death", the Edgar Allan Poe story that begins: "The 'Red Death' had long devastated the country. No pestilence had ever been so fatal, or so hideous."
In Ebola: The Natural and Human History of a Deadly Virus, Mr Quammen puts the frightening reality of Ebola - and the heightened language and hyperbole surrounding it - into perspective. This slender book is an expanded extract from his 2012 book Spillover: Animal Infections and the Next Human Pandemic, and it does a nimble job of situating this year's unnerving events in historical context, going back to the first recorded occurrence of the virus in 1976 and chronicling the scientific and medical efforts to understand it since.
As he did in earlier natural history books such as The Song of the Dodo and Monster of God, Mr Quammen combines on-the-ground reporting with research and interviews to give the reader a sharp-edge understanding of the subject at hand: what is known, what is not known and what may be in dispute. His book, like most writing about Ebola, is deeply unsettling, but it's also sober-minded, and in this respect, a standout in the floodlet of Ebola books, many of them quickie scare guides and medical thrillers (with portentous titles such as Ebola: The Final Plague, Ebola: Be Afraid, Be Very Afraid, Ebola: The Preppers Guide to Surviving Ebola, The Trojan Virus: An Ebola Bioterrorism Thriller and The Ebola Conspiracy), which seem intended to exploit public fears.
In these pages, Mr Quammen takes Richard Preston - the author of the 1994 best seller The Hot Zone - to task for his melodramatic approach to the subject, writing that readers should not take Mr Preston's lurid descriptions of Ebola's consequences literally - liquefying organs until "people were dissolving in their beds" or causing victims to "weep blood". (In a recent interview with The New York Times, Mr Preston said he now wants to update his book and make "the clinical picture of the virus more clear and accurate".)
Mr Quammen - like the journalist Laurie Garrett in her illuminating and encyclopaedic book The Coming Plague - shows in these pages that the reality of the virus is horrifying without any apocalyptic embellishment. He writes that experts "aren't sure exactly how the virus typically causes death"; rather, multiple causes - including liver failure, kidney failure, breathing difficulties, diarrhoea - seem to converge in "an unstoppable cascade". The "idea of immune suppression by ebolaviruses has also appeared lately in the literature", he says, "along with speculation that it might allow catastrophic overgrowth of a patient's natural populations of bacteria, normally resident in the gut and elsewhere, as well as unhindered replication of the virus itself".
Much of this book reads like a detective story, tracing the intrepid efforts of microbe hunters to understand how this dangerous virus works - the dynamics of transmission, the geographical pattern of outbreaks - and possible approaches to treatment. There are some harrowing accounts of forays by scientists into disease-ridden (and cobra-infested) bat caves in Uganda, and an equally chilling story about an infectious-disease research scientist who accidentally stuck herself with a syringe that she'd been using to inject Ebola-ridden mice.
Over the years, considerable attention has been devoted by scientists to unraveling the mystery of where the virus lurks when it is not infecting humans, that is, an animal host or reservoir, where it can exist more or less benignly. The chief suspected reservoirs, Mr Quammen says, are certain types of fruit bat, which are present in parts of Central and West Africa. The diversity of bats ("one in every four species of mammal is a bat," he writes), "their ancientness" (they evolved "to roughly their present form about 50 million years ago") and their abundance in large, intimate communities, he argues, might have contributed to their capacity to host a wide variety of viruses, just as their migratory habits (some journey as much as 800 miles between their summer and winter roosts) might have increased "the likelihood that they, or the viruses they carry, will come in contact with humans".
Why do "zoonoses" (animal infections that jump over into humans, such as Ebola, SARS, AIDS, Lyme disease, West Nile fever, swine flu, bird flu) seem to be more and more common? Mr Quammen suggests that when humans "encroach upon the host populations" of a pathogen - "hunting them for meat, dragging or pushing them out of their ecosystems, disrupting or destroying those ecosystems" - "our action increases the level of risk". As a veterinary disease ecologist named Jon Epstein observes, "It increases the opportunity for these pathogens to jump from their natural host into a new host."
In some cases, the microbe remains benign in the new host as it was in the old one. In other cases (such as HIV), the pathogen - especially RNA viruses given to high rates of mutation and replication - not only gets a foothold in the new host, but also adapts and evolves and causes serious illness.
An important study published by the journal Science in August, Mr Quammen says, addressed the Ebola virus variant involved in this year's outbreak, which is the worst in the history of the disease. The study, he writes, indicated that "the virus was mutating prolifically and accumulating a fair degree of genetic variation as it replicated within each human case and passed from one human to another".
The high rate of mutations in the virus suggest "that continued progression of this epidemic could afford an opportunity for viral adaptation", it said, "underscoring the need for rapid containment". Or, in Mr Quammen's words, "the higher the case count goes, the greater the likelihood that Ebola virus as we know it might evolve into something better adapted to pass from human to human, something that presently exists only in our nightmares".
As for our still highly provisional scientific understanding of ebolaviruses, Mr Quammen reminds us that it "constitutes pin pricks of light against a dark background".
© The New York Times News Service 2014
