Food-borne streptococcal epidemics

Approximately two days after a high school final year farewell party a striking number of pupils and teachers became ill with pharyngitis. The regional public health medical office carried out a questionnaire study with a control group of younger pupils. The regional food control unit studied the preparation and handling at food. Some bacterial cultures received from general practitioners were identified by the regional clinical-microbiological laboratory. Seventy-six percent of the 216 exposed pupils who answered (94% response rate) against 15% of 238 answering in the control group (83% response rate) became ill. The peak incidence was two days after the party. The infectious agent was beta-haemolytic streptoccoci group-A, T-type 25. A salad made of pasta and vegetables that were not cooked and handled properly must have been the vehicle of infection although no salad was left for cultivation. Salads made of pasta must be prepared with great care and effectively cooled. When suspecting a food-borne epidemic, clinicians should immediately inform the regional public health medical office, and the municipal food control unit must take part in the investigations. It is important that bacterial cultures are identified by the regional clinical-microbiological laboratory. It should be considered to make it mandatory that the involved personnel accepts clinical examination and microbiological sampling in cases of suspected food-borne infection.