Ignaz Semmelweis was ahead of his time. Working at Vienna General Hospital in the 1850s, the Hungarian physician was one of the first to adopt the idea that germs cause disease.
Semmelweiss noted that doctors would perform autopsies in the hospital's basement, then care for healthy pregnant women without cleaning their hands. Many of the women developed fatal fevers, and Semmelweis reasoned that the doctors were transferring some kind of infectious agent from the corpses to the women.
Contagion was a radical idea at a time when illness was thought to be caused by bad blood or other mysterious forces, and Semmelweis was ridiculed for his ideas.
Today, we know that most acute diseases are caused by bacteria, viruses and other agents.
Now, a growing number of latter-day Semmelweises are advocating an even more radical notion--that viruses and bacteria play a major role in many chronic diseases where infection has never been suspected.
At a time when much research focuses on the genetic underpinnings of disease, researchers say, it is time to take a fresh look at how an old foe--infections--can interact with genes to produce chronic disease.
If they are right, physicians might soon have new antibiotic and antiviral weapons to add to their arsenal for treating heart disease, Alzheimer's, kidney stones, gallstones and a variety of other chronic conditions. It might even be possible to develop vaccines to prevent some of these conditions.
Already, bacteria and viruses have been firmly linked to ulcers, liver cancer, cervical cancer, leukemia and Kaposi's sarcoma.
Strong evidence is also unfolding for other diseases:
* Epidemiologists have found that a majority of heart disease patients have been infected with a common bacterium, and Canadian researchers recently reported a mechanism by which it could trigger heart disease. Some researchers suspect that as many as 80% of all cases of heart disease are linked to infections.
* Pennsylvania scientists have found the same bacterium in the brains of patients with Alzheimer's disease.
* Finnish biologists have strong evidence that a previously unrecognized bacterium can produce kidney stones.
* More tentatively, other researchers have linked infections to a broad spectrum of diseases, ranging from Crohn's disease and irritable bowel syndrome to obsessive-compulsive disorder, schizophrenia, multiple sclerosis and arthritis (see box).
Studies Focusing on Antibiotics
The links to infection raise "the prospects for treating and preventing these chronic diseases," said biologist Paul Ewald of Amherst University. "If it's a bacterium that is susceptible to a wide range of antibiotics, that is incredibly encouraging."
Already, some small studies have suggested that antibiotics might prevent heart attacks, and three large clinical trials enrolling nearly 8,000 people have begun or are beginning. Neurologists are also preparing a trial using antibiotics to treat Alzheimer's disease, and it is likely that trials for other chronic diseases are on the horizon.
That doesn't mean you are going to be able to throw away your blood-pressure medicine or eat more fatty foods. Infections are just one more risk factor to add to the complex equations determining risk. Some researchers believe, for example, that controlling infections might have the same benefit for heart disease patients as lowering cholesterol.
"This is an idea whose time has come," said Dr. W. Ian Lipkin of the UC Irvine School of Medicine. "We have been tracking [this] for many years, and it is finally achieving some respectability."
The new discoveries are occurring in part because some researchers are choosing to look for links to infectious agents. But more important, perhaps, has been the development of sophisticated DNA-based techniques for identifying the presence of trace quantities of bacteria or viruses.
Polymerase chain reaction (PCR) technology, widely heralded for its use in providing genetic fingerprints of humans, can be used to fish out the genetic fingerprints of viruses or bacteria in human tissue, even though the organisms are present only in minute quantities.
"If [the viruses or bacteria] were causing disease in an obvious way," Ewald adds, "we would have seen it long ago. It shouldn't surprise us . . . that every new one we find tends to be a little more cryptic."
The godfather of the new movement is Dr. Barry J. Marshall, who was at the Royal Perth Hospital in Australia in 1981 when he and Dr. J. Robin Warren began studying an unidentified spiral bacterium that they observed in stomach linings.
After several years of study, they concluded that the bacterium, named Helicobacter pylori, is the cause of most ulcers not associated with over-ingestion of painkillers--an idea that the vast majority of physicians considered laughable at the time. They also found that eradicating the bacteria, which is found in the stomachs of a third of Americans, cured the ulcers.
