Groups A, B and C are further divided into approximately 40 serotypes, designated by numbers. It is an acute bacterial disease characterised by diarrhoea, fever, nausea, vomiting and abdominal cramps. Toxaemia may be present. Typically the stools contain blood, mucus and pus, although some cases will present with a watery diarrhoea.
Asymptomatic infections occur.
The illness is usually self-limited, and lasts from several days to weeks with an average of four to seven days. In contrast, Sh. dysenteriae is often associated with serious disease and a high case fatality rate. Public Health Significance and Occurrence Occurrence is worldwide. Two-thirds of the cases and most of the deaths are in children under 10 years. The disease is very rare in infants under six months of age.