The Biography of a Germ by Arno Karlen, Victor Gollancz, 拢15.99, ISBN
0575066059
鈥淲HY me?鈥� has been the perennial complaint of the sick, kicking against the
unfairness of it all. Society, by contrast, has been all too ready to point to
the moral behind the malady. Leprosy and plague revealed God鈥檚 wrath, syphilis
was the wages of lust, cholera the punishment of the poor for their squalid
ways, and gout that of the rich for swilling too much port鈥攁nd so on, all
the way to AIDS.
The punitive messages that microbes supposedly tell have generally been
simple and straightforward: disease is the mark of ungodly folk, filthy habits
and foul minds. But once in a while nature plays a dirty trick on the
respectable and righteous. When polio struck on both sides of the Atlantic in
the first half of the 20th century, it was the well-scrubbed children of the
hygienic middle classes who were worst hit, while the grubby street urchins of
the slums got off more lightly. Likewise, in 1976, how unjust it seemed that
honourable American veterans were the ones who perished in the first outbreak of
what became known as legionnaires鈥� disease? And why, at the very same time, were
so many God-fearing, prosperous suburban families in the north-eastern US, from
Maryland to Maine, going down with a raft of vicious symptoms: high fever,
severe inflammation, a splitting headache, muscular aches and swollen
joints?
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Arno Karlen teases out the answers in his erudite and entertaining study,
The Biography of A Germ. In this far from ordinary biography, his hero
is a microorganism whose complex life story of adroit evolutionary adaptations
is recounted with all the literary mastery and charm that made Karlen鈥檚 Man
and Microbes: Disease and plagues in history and modern times(1995) so
memorable.
Measuring one ten-thousandth of a millimetre, the bacterium Borrelia
burgdorferi(Bb), makes an intriguing voyage, mainly in the gut of
the deer tick. That arthropod vector itself goes through a complex two-year,
three-stage life cycle. First, it hatches as a six-legged larva, in need of a
host, preferably a white-footed mouse. As it gorges on the host鈥檚 blood, it can
in some cases pick up Bb. The larval tick then lies dormant till the
next summer when, emerging as an eight-legged adult, it attaches itself to a
white-tailed deer or similar large mammal for a further blood meal, after which
it mates. The female lays her eggs and the cycle starts up again. All the while,
Bb is enjoying welcome shelter and nourishment in the tick鈥檚 gut.
It is when host ticks find their deer prey living in close proximity to
civilisation that humans run the risk of getting bitten, leading to the malaise
and, in severe cases, to arthritis, chronic fatigue, and neurological and
cardiac damage. What from the parasite鈥檚-point of view constitutes a highly
effective series of adaptations, proves a disaster for the patient.
The link between those symptoms and a guileful germ was quite unsuspected
back in the mid-1970s, when New England doctors were reduced to serving up a
ragbag of putative explanations for the rash of cases then appearing. Some
notoriously put it all down to problem patients or to mass hysteria. Two
resourceful Connecticut mothers, however, kicked up a fuss, and forced the Yale
medical faculty to address their children鈥檚 sickness head-on.
Alan Steere made the breakthrough. He noted similarities with Rocky Mountain
spotted fever and other rickettsial disorders. The discovery that many of the
victims had been bitten by ticks put the epidemiologist hot on the microbe鈥檚
trail. The stage was set for the Swiss-born, Montana-based bacteriologist and
specialist in relapsing fevers, Willy Burgdorfer, to identify the villains.
Dissections of deer ticks under the microscope revealed silvery, wriggling,
corkscrew-shaped spirochaetes. Identified as a member of the genus
Borrelia (a group of tick-borne spirochaetes discovered in the 19th century
by Am茅d茅e Borrel), the species was named after Burgdorfer
himself.
Ambushed by ticks
From then on, control of the outbreak became relatively routine: the disease
proved responsive to antibiotics, and later there were vaccines. Though the
condition remains common, the scare phase was over for what came to be named
Lyme disease, after the Connecticut community most severely affected.
Why, then, was it well-heeled New Englanders who suddenly found themselves
laid low by what seemed to be a new disease? Why them? Curiously, the answer lay
in environmental regeneration. The New England colonised by the Pilgrim Fathers
was a land of dense forests, judged pestilential by the settlers. Hard labour
turned it into fine farmland, but in time, as big agriculture moved west and
great cities developed from Boston to Baltimore, great swathes of it reverted to
scrubland. This provided the perfect site for the swish suburbs sought by
modern, nature-loving town workers. Who would not want to bask in parkland
greenery in a new Edenic idyll, decked out with deer, chipmunks, raccoons and
other cute mammals?
As ever, there was a sneaky serpent in paradise, in the form of our friend
Bb, whose tick host found the multiplying suburban wildlife, especially
the deer, a superb food reservoir. So nature had her revenge. How ironic that
the seedy city thus proved, in some ways, safer than the pastoral utopia. And it
presented a thorny dilemma to suburbanites too green and politically correct to
embrace such quick-fix solutions to their medical problems as liberal use of
pesticides or culling deer.
A rewarding read, The Biography of a Germ does for Bb what
Darwin did for earthworms or Niko Tinbergen for the herring gull, tracing the
secret life of a hitherto neglected organism. Karlen鈥檚 book also forces the
reader to ponder once more the economy of nature. Which species are the really
smart ones? Is there the slightest evidence that natural selection bears out our
views as to what is fit, healthy and progressive?
In a few million years, are humans more likely to be still around than pesky
bugs like Borrelia burgdorferi? For all Karlen鈥檚 hopefulness, that
seems a long shot.