Sepsis

Sepsis is a medical emergency in which the body's reaction to an infection becomes so disordered that it starts to injure its own organs. The international definition agreed in 2016 describes it as organ dysfunction that threatens life and results from a dysregulated response of the host to infection. Bacteria cause most cases, but viruses, fungi and parasites can also trigger it, often starting from an infection of the lungs, urinary tract, skin or gut.

Chemical signals released to fight the infection spread through the bloodstream and set off widespread inflammation, tiny blood clots and leaky blood vessels. Blood flow to the tissues drops, cells get less oxygen, and organs such as the kidneys, lungs, liver and brain can begin to fail. In septic shock, the most severe form, blood pressure stays dangerously low and circulation and cell metabolism are so disturbed that the risk of death rises sharply.

Anyone with an infection can develop sepsis, but it is more common in older adults, newborns and young children, pregnant women, people in hospital and those with weakened immunity or long-term illness. Fast treatment, including antibiotics, is critical, and drug-resistant microbes make it harder. Sepsis is linked to roughly one in five deaths worldwide.