Harmless to healthy people and present in/on all of us, Candida albicans becomes a one-celled monster when it finds a weak immune system. It's notorious for afflicting three-quarters of all women at some time in their lives with the itching, irritation, burning sensation, and soreness associated with so-generically-called yeast infections. Candidiasis, the technical name for those infections, also shows up in the form of diaper rash on a baby, jock itch, or white milky-looking thrush on the tongue.

The far more sinister Cryptococcus neoformans this year will kill hundreds of thousands of people, as it does each year. Preying on those with suppressed immunity, it's found in soil all over the world -- especially where lots of birds, particularly pigeons, leave their droppings. We all inhale C. neoformans' microscopic, airborne fungal spores, mostly with no problems. But people whose immune systems are compromised -- because they have untreated HIV infection, take immunosuppressive drugs, receive an organ transplant, or are pregnant, for example -- are at risk for developing the pneumonia-type illness cryptococcosis or, if the infection spreads to the brain, the life-threatening cryptococcal meningitis.

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Thinking past these unpleasantries, consider that 50 billion pints and 67 billion cans of beer are consumed in the United States each year, according to the Beer Institute. "He was a wise man who invented beer," said Plato.

In fact, said Jim Koch, founder and owner of the Boston Beer Company, brewers of Sam Adams, "There's some debate about which came first, beer or bread. It appears most likely it was beer."

Koch called yeast -- specifically the S. cerivisiae used in both beer and bread -- a "miracle organism." He explained, "There are people who will contend that civilization began so that humans could make beer. They figured out how to grow grain, but needed to figure out how to turn the grain into a source of nutrition and safe hydration."

The alcohol produced by yeast's fermentation -- breaking down carbon into carbon dioxide and ethanol (alcohol) -- is among the most powerful sterilizing agents available. This is why, Koch said, even the Pilgrims didn't pack the Mayflower with barrels of water that could carry all kinds of harmful organisms -- typhus, cholera, and hepatitis among them.

"Instead, they provisioned it with beer," he said, "almost a gallon a day for every man, woman, and child."

Boston Public Library/Flickr Boston Public Library/Flickr

It wasn't that the pleasure-phobic Puritans were closet lushes. "The reason was beer was a safe form of hydration," said Koch. The alcohol produced by yeast's fermentation kills every potentially harmful organism in the beer. "When God made the universe," said Koch, "he or she made nothing harmful to human beings that can grow in beer."

Gods have been invoked, thanked, and cursed since the Greeks credited Dionysus with creating wine and winemaking. But it was the Frenchman Louis Pasteur who revealed new knowledge that even the gods had never imparted. In 1857 Pasteur created the field of microbiology when he proved that alcoholic fermentation is conducted by living yeast rather than by either a chemical reaction or by magic. Viniculturists ever since have sought to capitalize on the new understanding about yeast that microbiology opened up for them.