An outbreak of aseptic meningitis due to echovirus 30 associated with attending school and swimming in pools

OBJECTIVES: To identify the risk factors of an outbreak of meningitis associated with echovirus 30-infection that occurred in Rome, Italy, in late 1997 among children from two different schools. METHODS: A case-control study was carried out. A case was defined as a child from either of the two schools, A or B, who presented meningitis-like (fever, headache and vomiting), diarrhea, or respiratory tract symptoms. All asymptomatic students were included in the analysis as controls. RESULTS: Among 446 pupils (80%) who answered the questionnaire, 68 met the case definition. Twenty pupils developed a meningitis-like illness. Echovirus 30 was isolated from cerebrospinal fluid (CSF) in four and from stools in six. Forty-eight pupils reported other symptoms. The attack rate was 10.8% in school A and 0.8% in school B for meningitis-like illness; it was 12% and 10%, respectively, for other enterovirus-like illnesses. The risk of meningitis-like illness was higher among children attending school A (crude OR = 14.9; 95% CI = 4.3-52.1), among children using any public pool (OR = 3.8; 95% CI = 1.5-9.9) and those using an outside swimming pool X (OR=13.4; 95% CI=2.7-65.8 versus no swimming pool and OR = 8.3; 95% CI = 1.1-62.6 versus other pools). The epidemic curve appears to suggest a person-to-person transmission. CONCLUSIONS: The epidemic occurred by person-to-person transmission in a number of classrooms and at swimming pool X.