Why does salmonella cause serious illness in some people but not others?
For most people, a Salmonella infection causes gastroenteritis, an inflammation of the stomach and intestines that can mean several miserable days of diarrhea, cramps, fever or vomiting. Most people recover within a week. But severe diarrhea and dehydration can still be dangerous, even while the bacteria remain confined to the gut.
Salmonella infection typically causes gastroenteritis, characterized by diarrhea, cramps, fever or vomiting, which resolves within a week in most people. However, some patients develop severe symptoms, such as invasive infection where the bacteria cross the gut lining and enter the bloodstream, leading to sepsis. The source identifies 207 confirmed cases of a related strain of Salmonella Enteritidis in the UK, with 38% of patients requiring hospitalization.
Egg consumption is the primary suspect, though the source remains unconfirmed. Cross-contamination at food businesses was also identified as a possible route for bacteria transfer. Salmonella enters the bloodstream through multiple mechanisms, including injecting proteins into gut cells to make them engulf the bacteria, and altering the immune cell compartment to allow survival and multiplication.
Some strains, such as Typhimurium, Enteritidis, Choleraesuis, and Dublin, are more prone to spreading beyond the gut. Genetic factors, age, health conditions, and the amount of bacteria swallowed also influence the severity of the infection. The UK Health Security Agency's use of whole-genome sequencing helped trace the outbreak to imported eggs, but genetic similarity does not predict the severity of illness.
Pregnant women, babies, young children, and older people are advised to consume raw or runny eggs only if they carry specific safety marks.
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