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c8698a0
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b`d 'sbw` mn mwt any " bn@ drwyn" bynmlSwr@ l tzl HDr@ fy ldhkr@, ktb drwyn mdhkr@ khS@ qSyr@ tsjl lqlyl mn mftnh, w`dth, wsmth, wrqSth Hwlh bTwl lmmsh~ lrmly, wtdqyqh S`b lrD, wHbh ll'Tfl l'SGr snan, wmwhbth lmwsyqy@, wHmsh llqwmysh wlkhry'T . ktb drwyn 'nh fqd hw wym "zwjth" mt`@ drhm w'nys@ wHdthm fy `mrhm lmtqdm. l shk 'n lft@ lSGyr@ knt tdrk l'y md~ knt mHbwb@. thm ynhy drwyn m ktbh bqwlh : "fltHl `lyh lbrkt", wqd 'sqT hdhh lmr@, `l~ n..
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David Quammen |
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9b60ffd
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Each outbreak, by this view, represents a local event primarily explicable by a larger cause--the arrival of the wave. The main proponent of the wave idea is Peter D. Walsh, an American ecologist who has worked often in Central Africa and specializes in mathematical theory about ecological facts. "I think it's spreading from host to host in a reservoir host,"
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David Quammen |
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9b12f27
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Sir Peter Medawar, an eminent British biologist who received a Nobel Prize the same year as Macfarlane Burnet, defined a virus as "a piece of bad news wrapped up in a protein." --
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David Quammen |
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5976990
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disappointment, in science, is sometimes a gateway to insight.
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David Quammen |
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db06cf5
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People and gorillas, horses and duikers and pigs, monkeys and chimps and bats and viruses: We're all in this together.
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David Quammen |
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a426aa1
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When a pathogen leaps from some nonhuman animal into a person, and succeeds there in establishing itself as an infectious presence, sometimes causing illness or death, the result is a zoonosis.
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David Quammen |
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e43e1ba
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Ebola is a zoonosis. So is bubonic plague. So was the so-called Spanish influenza of 1918-1919, which had its ultimate source in a wild aquatic bird and, after passing through some combination of domesticated animals (a duck in southern China, a sow in Iowa?) emerged to kill as many as 50 million people before receding into obscurity.
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David Quammen |
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8c2ab2f
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Others are new and inexplicably sporadic, claiming a few victims (as Hendra does) or a few hundred (Ebola) in this place or that, and then disappearing for years.
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David Quammen |
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86c10b1
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Mad cow disease is caused by a prion, a weirdly folded protein molecule that triggers weird folding in other molecules, like Kurt Vonnegut's infectious form of water, ice-nine, in his great early novel Cat's Cradle.
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David Quammen |
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048cde5
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Identifying the new virus was only step one in solving the immediate mystery of Hendra, let alone understanding the disease in a wider context. Step two would involve tracking that virus to its hiding place. Where did it exist when it wasn't killing horses and people? Step three would entail asking a further cluster of questions: How did the virus emerge from its secret refuge, and why here, and why now?
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David Quammen |
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3db7736
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In ecological terms, we are almost paradoxical: large-bodied and long-lived but grotesquely abundant. We are an outbreak.
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David Quammen |
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0aab636
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A high jeopardy of extinction comes with territory. Islands are where species go to die.
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David Quammen |
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0e8c330
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increases of the infectivity rate may lead to large epidemics." This quiet warning has echoed loudly ever since. It's a cardinal truth, over which public health officials obsess each year during influenza season. Another implication was that epidemics don't end because all the susceptible individuals are either dead or recovered. They end because susceptible individuals are no longer sufficiently dense within the population. W. H. Hamer had..
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David Quammen |
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fa5cdc1
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The main problem facing a parasite over the long term, Burnet noted, is the issue of transmission: how to spread its offspring from one individual host to another. Various methods and traits have developed toward that simple end, ranging from massive replication, airborne dispersal, environmentally resistant life-history stages (like the small form of C. burnetii), direct transfer in blood and other bodily fluids, behavioral influence on th..
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David Quammen |
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266d0ad
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This elaborate concatenation of life-forms and sequential strategies is highly adaptive and, so far as mosquitoes and hosts are concerned, difficult to resist. It shows evolution's power, over great lengths of time, to produce structures, tactics, and transformations of majestic intricacy. Alternatively, anyone who favors Intelligent Design in lieu of evolution might pause to wonder why God devoted so much of His intelligence to designing m..
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David Quammen |
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87c3b55
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The ecosystem itself is not just a landscape full of plant and animal species; it's an intricate network of relationships, including those between predators and their prey, between flowering plants and their pollinators, between fruiting plants and the animals that disperse their seeds. Each such relationship constitutes a link between trophic levels.
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David Quammen |
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a26fa22
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Lyme disease, psittacosis, Q fever: These three differ wildly in their particulars but share two traits in common. They are all zoonotic and they are all bacterial. They stand as reminders that not every bad, stubborn, new bug is a virus.
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David Quammen |
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52f57d4
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Numbers can be an important aspect of understanding infectious disease. Take measles. At first glance, it might seem nonmathematical. It's caused by a paramyxovirus
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David Quammen |
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523b266
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It comes and it goes. But epidemiologists have recognized that, with measles virus, as with other pathogens, there's a critical minimum size of the host population, below which it can't persist indefinitely as an endemic, circulating infection. This is known as the critical community size (CCS), an important parameter in disease dynamics.
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David Quammen |
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cb3b5b2
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Hamer was especially interested in why diseases such as influenza, diphtheria, and measles seem to mount into major outbreaks in a cyclical pattern--rising to a high case count, fading away, rising again after a certain interval
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David Quammen |
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1a1448a
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Continuation of the outbreak depended on the likelihood of encounters between people who were infectious and people who could be infected. This idea became known as the "mass action principle." It was all about math. The same year, 1906, a Scottish physician named John Brownlee proposed an alternate view, contrary to Hamer's. Brownlee worked as a clinician and hospital administrator"
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David Quammen |
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282fefb
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Then there was a new epidemic--of fear," said Dr. Sam Okware, Commissioner of Health Services, when I visited him in Kampala a month later. Among Dr. Okware's other duties, he served as chairman of the national Ebola virus task force. "That was the most difficult to contain," he said. "There was a new epidemic--of panic." --
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David Quammen |
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4ab43b9
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Humanity badly needs things that are big and fearsome and homicidally wild. Counterintuitive as it may seem, we need to preserve those few remaining beasts, places, and forces of nature capable of murdering us with sublime indifference.
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David Quammen |
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78b583f
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R0 explains and, to some limited degree, it predicts. It defines the boundary between a small cluster of weird infections in a tropical village somewhere, flaring up, burning out, and a global pandemic. It came from George MacDonald.
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David Quammen |
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706a55f
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Als de hemel donker wordt met zwarte donderwolken, de grote bomen zwaaien in de wind, de pauwen zingen, hunker ik ernaar terug te rennen naar Gir.
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indian-lion
maldhari
panthera-leo-persica
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David Quammen |
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b51c83c
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An amplifier host is a creature in which a virus or other pathogen replicates--and from which it spews--with extraordinary abundance. Some aspect of the host's physiology, or its immune system, or its particular history of interaction with the bug, or who knows what, accounts for this especially hospitable role.
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David Quammen |
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7958ace
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Horses aren't native to Australia. They are exotic, first brought there by European settlers barely more than two centuries ago. Hendra is probably an old virus, according to the runic evidence of its genome, as read by molecular evolutionists.
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David Quammen |
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ad542e6
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If the virus had arrived in a different sort of big city--more loosely governed, full of poor people, lacking first-rate medical institutions--it might have escaped containment and burned through a
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David Quammen |
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63a5adb
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problem peaked in 1952 with an outbreak that killed more than three thousand victims, many of them children, and left twenty-one thousand at least partially paralyzed. Soon afterward, vaccines developed by Jonas Salk, Albert Sabin, and a virologist named Hilary Koprowski (about whose controversial career, more later) came into wide use, eventually eliminating poliomyelitis throughout most of the world. In 1988, WHO and several partner insti..
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David Quammen |
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2c77a33
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Their most telling improvement involved a fundamental parameter: population size of the hosts.
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David Quammen |
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5c42e4d
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One further factor, possibly the most crucial, was inherent to the way SARS-CoV affects the human body: Symptoms tend to appear in a person before, rather than after, that person becomes highly infectious. The headache, the fever, and the chills--maybe even the cough--precede the major discharge of virus toward other people. Even among some of the superspreaders, in 2003, this seems to have been true. That order of events allowed many SARS ..
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David Quammen |
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0d5f25e
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Advisory: If your husband catches an ebolavirus, give him food and water and love and maybe prayers but keep your distance, wait patiently, hope for the best-- and, if he dies, don't clean out his bowels by hand. Better to step back, blow a kiss, and burn the hut.
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David Quammen |
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68191c7
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The first rule of a successful parasite? Myxoma's success in Australia suggests something different from that nugget of conventional wisdom I mentioned above. It's not Don't kill your host. It's Don't burn your bridges until after you've crossed them.
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David Quammen |
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5cfacbb
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One further factor, possibly the most crucial, was inherent to the way SARS-CoV affects the human body: Symptoms tend to appear in a person before, rather than after, that person becomes highly infectious. The headache, the fever, and the chills--maybe even the cough--precede the major discharge of virus toward other people.
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David Quammen |
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487820a
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When the Next Big One comes, we can guess, it will likely conform to the same perverse pattern, high infectivity preceding notable symptoms. That will help it to move through cities and airports like an angel of death.
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David Quammen |
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7e3c6e9
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The downside was that hospital staff took the first big blasts of secondary infection; the upside was that those blasts generally weren't emitted by people still feeling healthy enough to ride a bus or a subway to work. This was an enormously consequential factor in the SARS episode--
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David Quammen |
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6bf5340
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There's a voice that says: "So what?" It's not my voice, it's probably not yours, but it makes itself heard in the arenas of public opinion, querulous and smug and fortified by just a little knowledge, which as always is a dangerous thing. "So what if a bunch of species go extinct?" It says. "Extinction is a natural process. Darwin himself said so, didn't he? Extinction is the complement of evolution, making room for new species to evolve. ..
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darwin
extinctions
future
so-what
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David Quammen |
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1825df5
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Influenza is caused by three types of viruses, of which the most worrisome and widespread is influenza A. Viruses of that type all share certain genetic traits: a single-stranded RNA genome, which is partitioned into eight segments, which serve as templates for eleven different proteins. In other words, they have eight discrete stretches of RNA coding, linked together like eight railroad cars, with eleven different deliverable cargoes. The ..
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David Quammen |
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d176637
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Lyme disease, psittacosis, Q fever: These three differ wildly in their particulars but share two traits in common. They are all zoonotic and they are all bacterial.
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David Quammen |
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af78bc2
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Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications." There's a nice word: ramifications. It's especially good in this context because, while the literal definition is "a structure formed of branches," from the Latin ramus, of course the looser definition is "implications." Darwin's tree certainly had implications."
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David Quammen |
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36d4ed0
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With influenza and many other diseases the order is reversed, high infectivity preceding symptoms by a matter of days. A perverse pattern: the danger, then the warning. That probably helped account for the scale of worldwide misery and death during the 1918-1919 influenza: high infectivity among cases before they experienced the most obvious and debilitating stages of illness.
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David Quammen |
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9032df2
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The song of the dodo, if it had one, is forever unknowable because no human from whom we have testimony ever took the trouble to sit in the Mauritian forest and listen.
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David Quammen |
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681ddfc
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a mutation in that strain might have made it especially aggressive, efficient, transmissible, and fierce.
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David Quammen |
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22d442a
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A few patients do bleed to death, Rollin said, but "they don't explode, and they don't melt." In fact, he said, the conventional term then in use, "Ebola hemorrhagic fever," was itself a misnomer, because more than half the patients don't bleed at all. They die of other causes, such as respiratory distress and shutdown (but not dissolution) of internal organs. It's for just these reasons, as cited by Rollin, that the WHO has switched its ow..
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David Quammen |