During the process of sepses, various gases and vapors are evolved, and the lower forms of animal and vegetable life grow and multiply in the putrefying substance. The active causes of putrefaction, or sepsis, depend on the growth and activity of microorganisms.

The changes that take place in a wound when organisms gain entrance to it and flourish on its discharges are collectively known as sepses or "septic processes".

Even the most beneficial bacteria can cause serious illness if they wind up where they are not supposed to be; for example, in the blood (causing sepsis) or in the web of tissue between the abdominal organs (causing peritonitis).

Sepsis is a serious and often deadly illness, yet it remains an unfamiliar threat to most of the general public, as well as one of the most difficult diseases for doctors to diagnose and treat.

The condition, which begins with an aggressive immune system reaction to an infection, kills 18 million people around the world every year, including around 260,000 in the U.S. By many estimates, sepsis—and its most severe form, septic shock—is the leading cause of death for intensive care patients in the U.S. and the 10th most common cause of death for everyone else in the country.

Only one in five Americans recognizes the term, according to a 2011 study commissioned by the nonprofit group "Sepsis Alliance", and of those survey participants who had heard of sepsis, most could not define it.

Even physicians, who learn about sepsis in medical school, often miss the early signs of sepses because they mimic other disorders and because the illness progresses so rapidly from what looks like a mild infection to a life-threatening situation.

As a result of these difficulties, doctors are often too late to start the necessary interventions; such as, antibiotics to obliterate the infection, drugs to counteract a perilous drop in blood pressure, and a mechanical ventilator to raise dangerously low oxygen levels.