Public awareness is still far too low, but the symptoms - which include diarrhoea, muscle pain, mottled or discoloured skin, itching, difficulty passing urine, chills and shivering, fever, and fast breathing - can be spotted by friends and family, or even the patient themselves. Until we all start to suspect sepsis, and say sepsis, the outlook won't get better.
So what Mr Cameron should have said was this: 'We can have, where clinically-appropriate and fully resourced, a truly seven-day NHS, assuming, of course, we can ensure that staff are fairly rewarded and also fully involved in designing the specific services that patients actually require, and desire, all week-round'.
There is one story dominating healthcare headlines right now - the government's pledge to deliver "a truly seven-day NHS". It's a commitment we all welcome in principle, but with dwindling GP numbers, tight budgets and concerns over existing primary and secondary care workloads, it has prompted a collective eyebrow raise and the question, 'how'?
Today the Overseas Development Institute are releasing a report called 'Financing the Future' which shows that free basic universal healthcare would cost $74 billion a year to deliver in the 33 poorest countries - equivalent to just 4% of total bailout support provided to the banks by the UK Government.
The NHS was established in 1948. Today it faces its biggest challenge since its inception. A failure to radically reform how we deliver new models of care across the NHS over the next five years could lead to a serious threat to this much-loved public service remaining universal and free at the point of need.
Relegating the four-hour target in importance and looking across a richer set of indicators like these could be an important way forward. But doing this will mean moving away from the weekly fix of headlines about hospitals 'underperforming' or, alternatively, meeting the target. Are politicians brave enough to go cold turkey on the totemic four-hour A&E target?
For the last six years I have worked in the beautiful country of Malawi but this is the first time I'm taking a moment to really try and understand the experience and once again the people of Malawi have enlightened me, educated me. Their strength, their unity and compassion is utterly breath-taking.