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Black Death

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More Death and Devastation

30 August 2004

More Death and Devastation

By Gwynne Dyer

The past month has brought us a choice of potential global disasters. Maybe the Black Death will return, and kill more than half the people on the planet as it once killed over half the population of Europe. Or we could have another meteor strike like the one that hit Antarctica 780,000 years ago, which could do much worse than that. Luckily, the Big One hit Antarctica during an ice age, which is probably why our proto-human ancestors survived it.

It has become orthodox to link the great extinctions of the archaeological record to huge asteroid strikes. The age of the dinosaurs was probably ended by a massive rock between four and seven miles (six and twelve km) in diameter that slammed into the sea off Mexico’s Yucatan peninsula 62 million years ago. There were massive tsunamis, continent-wide fires, and a lengthy “impact winter” when dust blasted into the stratosphere shrouded the sun and dropped temperatures by tens of degrees.

The dinosaurs didn’t make it — but many other species including our distant mammalian ancestors did. Recent research suggests that it was a mere fluke. Normally, you would expect the impact winter to be followed by an “ultraviolet spring” when the sun returned, shining through an atmosphere stripped of the ozone that normally screens out the harmful kinds of ultraviolet light.

Mutations, cancers and cataracts would have soared, plant photosynthesis would have been suppressed, and many species that survived the initial devastation would have died out. But the Yucatan strike hit a bit of the earth’s crust that is rich in anhydride rocks, producing a 12-year sulfide haze that blocked much of the ultraviolet.

It was worse the first time. The greatest extinction of all, 251 million years ago, when 90 percent of all ocean species and 70 percent of land species disappeared, was caused by an asteroid about the same size as the Yucatan one. It did more execution because it hit a different part of the planet, under different conditions — which brings us to the one we didn’t know about, the one that almost got us.

At the International Geophysical Congress in Glasgow on 18 August, Dr Frans van der Hoeven of Delft University of Technology in the Netherlands revealed that a similar asteroid hit Antarctica only 780,000 years ago, a mere blink of an eye in geological time. We are still here for three reasons, all of them flukes.

The asteroid broke up just before hitting the earth, creating five smaller impact craters over an area measuring 1,300 by 2,400 miles (2,100 by 3,800 km) rather than a single huge impact crater. Most of the pieces melted through the deep East Antarctic icecap before cratering the underlying bedrock, which limited the amount of dust boosted into the atmosphere. And there was already permanent winter over most of the planet, so it was much less of a shock to the biosphere.

“The extraordinary thing about this meteor strike is that it appeared to do so little damage,” said Professor van der Hoeven. “Unlike the dinosaur strike there is no telltale layer of dust (in the geological record) that demonstrates the history of the event. It may have damaged things and wiped out species but there is no sign of it.” Apart from the craters, the only indication that something big happened 780,000 years ago is that the earth’s magnetic field reversed at just that time.

Asteroids got the dinosaurs, but they didn’t get us. Whereas the Black Death did get Europe repeatedly between the fourteenth and the seventeenth centuries. Then it went away — but maybe not for good.

For the past century, the Black Death has been explained as an outbreak of bubonic plague, spread by fleas living on rats, but there have always been huge problems with that diagnosis. The fatality rate is far lower with bubonic plague, the incubation period doesn’t match, and the standard measure to contain the spread of the Black Death — quarantine — would not have worked if the vector was rats.

Now along comes “Return of the Black Death,” a book by Christopher Duncan, Emeritus Professor of Zoology at Liverpool University, and social historian Susan Scott, which convincingly argues that the Black Death was a haemorrhagic fever related to Ebola and other current quick-killer African diseases that spread directly from person to person. What made it so lethal was its extremely long incubation period, almost a month. That allowed plenty of time for an affected person to infect many others before the symptoms appeared.

It eventually died out in Europe because by the seventeenth century a large portion of the surviving European population had developed a genetic immunity to the virus. Scott and Duncan suggest that the immunity of between 5 and 20 percent of Europeans to the HIV virus is a relic, now diluted by time, to this tragically acquired immunity to the Black Death. But they also suggest that the original virus or some mutated successor is still out there somewhere — and that by now Europeans’ immunity is severely eroded, while nobody else has any at all.

Meanwhile, in Vietnam, three people have died in the past month from the A(H5N1) avian influenza virus, which has a two-thirds mortality rate in human beings. “We’re talking hundreds of millions of people afflicted if it is a pandemic out there lurking,” said Anton Rychener, Vietnam director for the UN Food and Agriculture Organisation. “What I have learned makes me shudder.”

If one thing doesn’t get you, another thing will. Gather ye rosebuds while ye may.

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To shorten to 725 words, omit paragraphs 3, 4 and 8. (“The dinosaurs…ultraviolet”; and “The extraordinary…time”)

The Return of the Plagues?

21 February 2003

The Return of the Plagues?

By Gwynne Dyer

On 28 January an eight-year-old girl from Hong Kong visiting relatives in southern China fell ill with influenza and was admitted to hospital. A week later she died, and since then her father has died of the same flu, while her nine-year-old brother lies gravely ill in an isolation ward in Hong Kong. The virus is outwardly similar to the A (H5N1) strain, also known as ‘bird flu’, that killed six of the eighteen people who were infected in the last outbreak in Hong Kong in 1997.

New strains of viral diseases that can kill human beings generally emerge by mutation as they hop back and forth between people and their domesticated animals. This exchange of viruses goes on all the time in farming areas — but it’s only when a lethal new virus crosses the species barrier AND THEN STARTS TO PASS FROM ONE PERSON TO ANOTHER that the alarm bells start to ring. They are ringing now.

“If this virus is transmissible from human to human then it is far more serious,” said a spokesperson for the World Health Organisation in Geneva on 19 February. The 1997 flu virus was stopped by slaughtering the 1.4 million chickens, ducks and geese in Hong Kong, but if the new one is already loose all over southern China that solution will not really work. Even the normal wave of flu that circles the world every year, slightly changed genetically each time, exacts a serious toll in lives, but once in a while something really lethal comes along. This could be one of those times.

The ‘Spanish flu’ pandemic of 1918 infected between 20 and 40 percent of the world’s population and killed 20 million people in four months, twice as many as died in the First World War — and the majority of the victims were young, healthy people who died of complications like bronchitis and pneumonia. If a flu virus like that appeared now, could it do as much damage?

Certainly the two subsequent flu pandemics, occurring after the development of anti-viral medicines, did not cause the same carnage. The impact of the 1957 ‘Asian flu’ pandemic was greatly reduced by mass vaccination: only one human being in six caught it, and it killed an estimated two million people worldwide. The 1968 ‘Hong Kong flu’ pandemic killed only a million people, and as in 1957 most of the victims were elderly. But viruses are not impressed by medical technology.

Despite the far higher standards of sanitation and medical care in the developed world, influenza death rates there have not been significantly lower than in poorer countries. Viral diseases mutate fast, antibiotics are no use against them, and good hygiene is no protection either. Bacterial diseases like cholera, anthrax and malaria have complex life cycles and mutate only slowly, so they are easy to contain — but if the latest version of ‘bird flu’ is transmissible between people, we could be looking at millions of deaths over the next year. Nor is that the worst that could happen.

The true nature of the ‘Black Death’ was long a mystery, but early in the 20th century, after doctors had found and described bubonic plague in India, experts jumped to the conclusion that a more virulent form of that disease, endemic in rats and transmitted to humans by their fleas, was the real culprit. This was a comforting conclusion, because it meant that it was a bacterial disease with a complicated life-cycle, easily contained by hygiene and antibiotics, that would never come back to trouble modern human beings.

But it never actually made sense, because the standard treatment for the Black Death, tried and tested over three hundred years, was to quarantine affected families and villages for forty days. That could not have worked if it were carried by rats, which do not respect quarantines. So two years ago professors Christopher Duncan and Susan Scott of Liverpool University suggested in their book, ‘Biology of Plagues’, that the Black Death was really an Ebola-like virus, a haemorrhagic fever transmitted directly from person to person. It is frighteningly plausible.

There were actually two Great Pandemics, and the first hit Europe and the Middle East in 541 AD. The Roman empire had been relatively unharmed by great plagues, apart from bouts of smallpox in 170 and measles in 250 which killed mostly children and left survivors immune, but the new plague was different. It returned about every ten years for the next two centuries, and reduced the population of the Mediterranean area by between 30 and 50 percent. Large parts of the Middle East and North Africa did not recover their pre-540 populations until about 100 years ago.

The plague called the Black Death appeared in Mongolia in the 1320s, and killed two-thirds of China’s population between 1330-50. It reached Europe in 1347, and killed between 30 and 40 percent of the population in the first onslaught. It returned at intervals of about a decade, with gradually diminishing lethality, until it disappeared at the end of the 17th century. The aching, the bleeding from internal organs, the red blotches on the skin caused by the effusion of blood under the skin, were all typical of Ebola-style fevers. Besides, bubonic plague, unlike the Black Death, did not disappear. There was an outbreak of bubonic plague in Glasgow as recently as the 1890s.

If Duncan and Scott are right, therefore, there is a virus out there somewhere, dormant for the moment while it tries out mutations that might break through the genetic defences that human beings evolved to defeat it last time, which could kill a significant portion of the human race in a year. The Black Death is not dead, it’s only sleeping. And in the meantime, the ‘bird flu’ may be coming.

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This is a longer article of about 950 words. To shorten to 775 words, omit paragraphs 3 and 9 (“If…times”; and “There are…ago”). To shorten further to 700 words, omit also paragraph 5 (“Certainly…technology”)