Today, let's talk about germs. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
That great master of
American doggerel, Ogden Nash, once wrote:
A mighty creature is the germ,Our knowledge of microbes is just over
300 years old. They were first observed in the late
17th century by the Dutch lens-maker Antonj Leeuwenhoek. He found that
these tiny "animalcules," as he called them, swam in
any body of water.
Though smaller than the pachyderm,
His strange delight he often pleases,
By giving people strange diseases.
But what about relating these small beasts to
disease? 150 years later, disease was rampant in
London. Half the newborn babies died, and the death
rate was far higher among the poor than among the
wealthy. Two things were also clear by then. One is
that London's drinking waters were, by and large,
simply loaded with microorganisms. The other is
that filth -- particularly raw sewage -- was to be
found everywhere in poor areas.
It's obvious enough to us that germs were causing
the diseases. But germs, after all, swam in waters
drunk by both the well and the sick. What was
obvious was that bad smells were found in unhealthy
neighborhoods. It seemed clear that stench, or
"miasma" as it was called, caused disease -- not
the water. It was the stink that people felt they
had to get rid of.
Then in 1849 and 1853 London suffered terrible
epidemics of cholera. In 1853, a physician named
John Snow started looking at statistics. He found a
high incidence of cholera among people who'd been
drawing water from a source called the Broad Street
Well. Then he found that the cesspool of a tenement
occupied by a cholera patient leaked into the Broad
Snow's report soon caused people to see that
cholera wasn't caused by noxious gases, but by what
was now called "fecalized water." He put people on
the track of the real agent of the disease. In 1857
Pasteur connected disease to bacteria, and in 1865
Joseph Lister found that he could kill
disease-carrying bacteria during surgery by
spraying a carbolic acid solution. Finally, in
1882, 29 years after Snow pinpointed the Broad
Street Well, the German physician Robert Koch
showed us how to make a disease-specific vaccine.
Koch, who'd found the bacterium that caused
anthrax, figured out how to make a vaccine to kill
Scientific discovery is like that. It can take
decades for people to overturn their old thinking.
The leap from unhealthy vapors to bacteria was
still a hard leap to make, even once the Broad
Street Well showed that a leap had to be made.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds