An outbreak of scarlet fever in a primary school.

Scarlet fever, due to infection with an erythrogenic toxin-producing Group A streptococcus, is an uncommon and generally mild illness, although serious sequelae do occur. In March 2009, 57 of the 126 (45%) pupils in a primary school in Lancashire, UK developed scarlet fever over a 4-week period. Infection was transmitted via direct contact between pupils, particularly among the youngest pupils. A significant degree of transmission also occurred between siblings. The median number of days absent from school was 3 (range 1-10 days). No children were hospitalised. Control measures, including hygiene advice to the school and exclusion of pupils for 24h while initiating penicillin treatment, were ineffective. The outbreak occurred against a background of an unusually high incidence of invasive Group A streptococcal infection. While there are national guidelines for the control of invasive disease, none exist for the control of scarlet fever outbreaks. This prolonged outbreak of scarlet fever highlights the need for an evidence based approach to outbreak management.