Was It in the Air? The Killers Too Small to See

Guinea pigs breathing air from a tuberculosis ward caught the disease. With ultraviolet light killing the germs in the same air, they didn’t. It’s the germs in the air that spread disease, not the air itself.

In Hamburg’s epidemic, the town of Altona next door was largely spared, on the same soil and under the same sky. Only its water differs: Altona filters it. The germ in the water decides it, not the soil.

Not everyone who swallows a germ falls ill, as with any infection. One man’s mild illness doesn’t show that the germ needs anything more.

I drank a culture of the cholera germ and got nothing worse than diarrhea. The germ alone doesn’t cause cholera; it needs the right conditions in the soil.

The cause of cholera is a comma-shaped bacterium, which I found in 1883 and 1884 in the intestines of its victims.

Anthrax comes from one particular germ. Grown outside any animal for eight generations, it still gives mice anthrax. Its spores survive in the soil for years, which is why some pastures stay deadly, whatever their air.

Decay doesn’t come about by itself. As Pasteur showed, it’s the work of germs, living things that get in from outside and multiply. What spreads infection is the germs, not decaying matter as such.

In my wards, 16 of 35 patients died after amputations before I began killing germs with carbolic acid, and 6 of 40 since. The air is the same as before; only the germs are gone.

Wounds fester for the same reason broth goes bad: germs get into them from outside. Kill the germs, on the wound, the instruments, and the surgeon’s hands, and wounds heal clean.

Broth boiled in a flask with a long, bent neck stays free of life, though air reaches it, because the germs carried by the air’s dust settle in the bend. Tip the flask so that the broth touches the bend, and it soon teems with microbes. They come from germs, not from the broth.

Microscopic life arises on its own in broths and infusions, from the decaying matter in them, whenever conditions allow.

Where two water companies supply the same streets, houses drinking Thames water taken below London’s sewers lose more than eight times as many people to cholera as houses drinking water taken above them. Same streets, same air, different water.

The Broad Street outbreak’s deaths cluster around one pump, and those spared drank other water: the workhouse its own well, the brewery’s men their beer. Bad air would have spared no one in the same streets.

Cholera is caused by a poison that multiplies inside its victims, leaves them in their waste, and spreads when others swallow it, mostly in water fouled by sewage. “For the morbid matter of cholera having the property of reproducing its own kind, must necessarily have some sort of structure, most likely that of a cell.”

In October, the doctors examined a woman with a foul-smelling cancer of the womb, washed only with soap, and went on to twelve women in labor. Eleven of them died, though no corpse was involved.

Childbed fever kills mothers four times as often in the doctors’ clinic as in the midwives’ clinic next door, though both breathe the same air. Since the doctors began washing their hands in chlorine after dissecting corpses, deaths have fallen from 18 in a hundred births to 2. The cause comes on the doctors’ hands, not from the air both clinics share.

Childbed fever comes from particles of corpses, which doctors and students carry on their hands from the dissecting room to the mothers they examine. Wash them off in chlorinated lime, and the fever goes.

Diseases like cholera and fevers come from miasma: bad air given off by rotting filth, sewage, and swamps. Clean away the filth and its smell, and the disease goes with it.