Sepsis is a poorly understood condition with a low public profile.
But new data suggest that it kills as many people as lung or breast cancer.
The researchers studied intensive care units in six European countries, the UK, France, Germany, Italy, Spain and the Netherlands.
From their data, they estimate that the cost of treating sepsis patients may be as high as $6.7million each year across .
Sepsis triggers a meltdown of the immune system. However, the condition can be difficult to diagnose as it can present a wide range of symptoms, ranging from fever and inflammation to abnormal blood clotting and organ failure.
It is thought that many cases of sepsis are mistakenly attributed to other underlying medical conditions such as cancer or Aids.
Wound
The condition, which is caused by bacteria entering a wound or body tissue, is often spread in hospitals as people with weakened immune systems are particularly at risk.
People who develop severe sepsis are usually seriously ill from other conditions, but the onset of sepsis greatly increases their risk of death.
Thirty per cent of people with sepsis die from its consequences within the first month of diagnosis, and 50% die within six months.
Eight out of 10 patients who die from major injuries, such as those sustained in a road traffic accident, die from sepsis as a result of their initial injury.
Professor Graham Ramsay, president-elect of the European Society of Intensive Care Medicine (ESICM), said: "This study is very important because it is the first time we have had statistics which show the extent of the problem in Europe.
"Hopefully this will be the first step to raising awareness of this terrible condition amongst policy-makers and the public."
Treatment
Until now there has been no way of treating sepsis other than to give patients antibiotics to try to minimise the severity of their symptoms.
But a study, published on the website of the New England Medical Journal, shows that a new drug, Xigris can help to save lives.
In clinical trials, the drug, developed by the pharmaceutical giant Eli Lilly, cut the risk of death among people with severe sepsis by nearly 20%.
Xigris is an artificially created version of a naturally occurring protein called Activated Protein C.
It appears to be able to control the inflammation and clotting in the blood vessels associated with severe sepsis.