Clinical Information

Incubation period

1 to 7 days.

Common clinical features

Bloody diarrhoea, S. sonnei generally mild other species more severe.

Reservoir

Human gastrointestinal tract.

Transmission

Faecal oral from cases with diarrhoea, in households, and institutions, mainly those containing young children. Occasionally spread by food and water.

Other relevant features

S. sonnei is endemic in England and Wales and usually causes a mild illness. S. boydii and S. dysenteriae, and most S. flexneri infections, originate outside the UK and present clinically as dysentery (diarrhoea with blood, mucus, and pus). S. dysenteriae may be associated with serious disease, including toxic megacolon and the haemolytic uraemic syndrome.