Why does Salmonella cause serious illness in some people but not others?

raymond orton/Shutterstock For most people, a Salmonella infection causes gastroenteritis, an inflammation of the stomach and intestines that can mean several miserable days of diarrhoea, cramps, fever or vomiting. Most people recover within a week. But severe diarrhoea and dehydration can still be dangerous, even while the bacteria remain confined to the gut. In a small minority of patients, however, Salmonella crosses the gut lining and enters the blood. In the current UK outbreak, seemingly…