Ignaz Semmelweis isn’t a household name, but he should be. In mid-19th-century Austria, one of the great causes of death among pregnant women was puerperal fever — a nasty infection that affects a woman’s reproductive organs during or after childbirth, and without treatment, normally results in death. At the time Semmelweis was serving as a physician in Vienna General Hospital, the mortality rate from puerperal fever was between 10 and 35 percent.

But the hospital beds were clean, and the rooms sterile. Even more curious, the midwives’ ward, with a fraction of the sophistication, had a third the death rate of the doctors’ wards, raising a puzzling question to Semmelweis: If the hospital was so clean, why were so many mothers dying?

The discovery he eventually made led to one of the greatest revolutions in medical science: hand washing. He realized that the spread of puerperal fever wasn’t the result of poor training or unclean sheets; it was the germs living on the hands of hospital staff — and conversely, not on those of the midwives.

Next to nothing was known at the time about how infectious diseases spread (or what certain diseases even looked like), and nurses would routinely dump old tools into general bins for later use. No one washed their hands because no one thought they were dirty. It was only after Semmelweis began requiring nurses and doctors to use chlorinated lime solutions that mortality began to fall. In late 1842, the death rate had peaked at 32 percent. By August 1848, roughly one year after hospital staff began washing their hands, the rate finally hit zero. Puerperal fever was gone.

What Ignaz Gave Us, and What We Still Need to Learn

The story of Ignaz Semmelweis helps explain a lot of the medical practices we today take for granted. Decades of scientific discovery have led to a way of practicing medicine and managing hospitals that no longer sees physicians smoking by patients’ bedside. Hospital doors open on their own — and if they don’t, nifty dispensers of hand sanitizer tend to sit on the walls beside them. Patients are told to let their nurses know if they have a cold.

These practices feel automatic. And yet, the sobering truth is that while puerperal fever made its exit over a century ago, hospital-associated infections are still a threat. The Centers for Disease Control and Prevention estimates that nearly two million people get infections from their stay in a hospital each year, and roughly 100,000 of them go on to die from those infections. Sterile waiting rooms and stale hallways do little to prevent bacteria from spreading between vulnerable patients and hospital staff. And without separate examination rooms for well patients and sick patients, people may enter with the sniffles and leave with Methicillin-resistant Staphylococcus aureus, or MRSA.

The problem is also covert in clothing. This past January, the Society for Healthcare Epidemiology of America (SHEA) released its suggestions for health care personnel to minimize the number of infections spread through contact in non-operating settings. Much of the transmission, they found, happens innocently through doctors’ iconic white coats. Unfortunately, little evidence suggests the coats should go.

"While studies have demonstrated the clothing of health care personnel may have a role in transmission of pathogens, the role of clothing in passing infectious pathogens to patients has not yet been well established," Dr. Gonzalo Bearman, lead author of the study and member of SHEA's Guidelines Committee, said in a statement.

And it’s not just their coats; the humble stethoscope may also be a breeding ground for germs. A recent study showed that stethoscopes are, on average, dirtier than doctors’ own palms. Researchers took swabs of both the instrument and several regions of the hand and found that all but the doctors’ fingertips were dirtier than their stethoscopes. Lead investigator Dr. Didier Pittet argued the tool made it easy for diseases to be transmitted.

"By considering that stethoscopes are used repeatedly over the course of a day, come directly into contact with patients' skin, and may harbor several thousands of bacteria collected during a previous physical examination,” he said, “we consider them as potentially significant vectors of transmission.”

By many measures, hand washing has been solved as a problem. If a doctor fails to wash her hands before examining a patient it’s because she forgot, not because she didn’t know better. But this cognizance has to be a two-way street. Patients need to feel, and be, partly responsible for the cleanliness of their examination. Doctors must take every precaution they can to keep bacteria at bay, and patients must do their part to keep doctors honest. Your health is important, Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, told ABC News, so ask questions. "It is a perfectly reasonable thing to inquire about.”

Cleanliness is a Pursuit, Not a Perk

An interesting thing happened when Ignaz Semmelweis got fired in March of 1849 for his controversial methods: Puerperal fever made a slight comeback. With less oversight, the staff stopped washing their hands. Semmelweis stewed over the dismissal, writing scornful open letters about the medical profession’s refusal to progress. In 1865, he was committed to an asylum, where he died at the age of 47.

It was only after Louis Pasteur, the French chemist famous for his discovery of vaccination and, of course, pasteurization, that Semmelweis’ theories began to take hold. Pasteur published his germ theory of disease. People noticed. Science developed antiseptics, and years later, began installing tiny canisters of Purell that people never notice, for patients that desperately need them. Thanks to Ignaz Semmelweis, cleanliness stopped being a perk of health care, and instead became a pursuit.