An Epidemiological Investigation of a Scarlet Fever Outbreak at a Kindergarten in Taichung City
1998 Vol.14 NO.7
Scarlet fever is caused primarily by group A $ -hemolytic streptococci. Symptoms include: acute fever, sore throat, bloody eyes, nausea, vomiting, fatigue, headache, loss of appetite, tonsillitis, rash, decortication, or strawberry tongue. Most patients will recover, with some developing complications such as acute glomerulonepluitis and acute rheumatic fever. For prevention, an epidemiological investigation of the infection to understand the characteristics of its agents and hosts is most important.
The study used the retroactive cohort follow-up method to interview children of the kindergarten with a structured questionnaire. The questionnaire contained items such as personal information, clinical symptoms, time of onset, use of school bus, and whether family members or friends in contact had similar clinical symptoms. Between 19 and 23 December 1997, throat swabs were taken of all children for culture and confirmation diagnosis. Blood specimens were also taken from some in-patients and out-patients for antistreptolysin 0 (ASLO) antibody titer testings. 25 children met the criteria of suspects; and of them, 14 met the criteria of a case: 5 boys and 9 girls, giving an attack rate of 8%. No cases of acute rheumatic fever or acute glomenilonephiitis complications were found. The outbreak was considered an outcome of close contact among children in the class. Two facts were noted from the incident: 1) only 36.4% of the continued cases showed an increase of ASLO antibodies; and 2) the duration between the time of onset and the time of laboratory testing was not related to the increase of ASLO, implying that the increase of ASLO antibodies by blood testings was not an effective predictive factor of group A hemolytic streptococcal infection.