How do STEC infections manifest?

The onset of STEC infection in the intestine typically includes:

• Watery diarrhoea (episodes of diarrhoea can be frequent and numerous)
• Bloody diarrhoea (blood in stools may appear a few days after the onset of illness)
• Severe abdominal pain
• Nausea and vomiting
• Fever (sometimes absent or generally low-grade)

Symptoms usually appear 3-4 days after exposure (e.g., through the consumption of contaminated food). This gastrointestinal phase can resolve spontaneously within a week or progress to a more severe clinical form, Haemolytic Uremic Syndrome (HUS). In HUS, symptoms like pale skin and mucosa, drowsiness, low urine output (oliguria), widespread oedema (fluid accumulation in tissues) with weight gain, jaundice, and seizures may occur. HUS often coincides with an improvement in diarrhoea. In severe cases, HUS can manifest shortly after the onset of STEC infection symptoms (2-3 days). In that case, the typical HUS manifestations can overlap with gastrointestinal symptoms.