There was a rapid rise in Shigellosis in East Anglia in 1992 to 400 compared with an average for the preceding decade of a little over 50. By contrast, in the 1960s, the UK figure was as high as 50,000 cases per year. The 1992 East Anglian rise is still less than for England and Wales as a whole. Shigellosis, occurs in two main settings - either as sporadic cases with moderate diarrhoea and abdominal pain with mucus and blood in more severe cases or as an outbreak where onset may be staggered. The incubation period is 1-7 days.
Transmission is patient to patient mainly.
Food and water are uncommon vehicles. Essentially the vehicle is liquid, infected, stool. In principle, the period of infectivity is while the organism persists in the stools though in practice the asymptomatic excretor poses negligible risk. Untreated, shigella remains in the stools for a median period of 17 days, compared with 28 days for salmonellae. In general, children should be excluded from school until recovery from diarrhoea is complete, say 48h after cessation of symptoms.