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Outbreak of Aseptic Meningitis in Riyadh, 1996.


In the period from January to June 1996, there was an average of 50 cases of meningitis in children in Riyadh City per month, a fivefold increase. This study aims to identify risk factors for spread of the disease.


All cases of meningitis admitted to five Riyadh city governmental hospitals between June 1995 and July 1996 were reviewed. Cases of meningitis were grouped into bacterial (BM) (a bacterial pathogen or antigen identified in the cerebrospinal fluid) (CSF), partially treated bacterial meningitis (PTM) (patient received antibiotics before having lumbar puncture) or aseptic meningitis (ASM) (no antibiotics before lumbar puncture, and CSF suggestive of ASM). Newly diagnosed cases of ASM (N=35) and 70 controls matched by age, sex and neighborhood were interviewed.


The 285 cases of meningitis admitted included 184 (65%) ASM, 45 (16%) PTM, and 56 (20%) BM. The age of ASM cases ranged from 8 days to 13 years (median=3 years). Echovirus-30 was isolated from the stool, CSF, and nasopharyngeal washings of 4 ASM patients in one family, and an enterovirus was isolated from 6 other ASM patients. Seven antibiotics, prescribed in different combinations for an average 8 days, were given to 153 (83%) ASM patients. Ten families had more than one concurrent case of meningitis. Patients lived throughout Riyadh City. Families with cases of ASM evacuate their sewage-holding tank a mean (± SD) 5.0 + 7.3 times per year compared with 2.1 ± 5.6 in control-families (t-test, p<0.01). Twenty cases (57%) and 13 controls (19%) had sewage overflow around their houses (Odds ratio [OR]= 5.8; 95% confidence interval [95% CI]= 2.2-16.1). In the 2 weeks preceding ASM onset, at least one other family member suffered from fever (OR 4.5; 95% CI 1.6-12.8), marked headache (OR 13.2; 95% CI 3.1-65.8), or vomiting (OR 17.3; 95% CI 1.9-397). Fifteen case-families with ASM visited another family with a sick child within the 2 weeks preceding ASM onset compared with 5 control-families (OR 9.8; 95% CI 2.8-36).


The outbreak was mainly due to ASM, most likely due to Echovirus-30. Transmission of the disease was probably person-to-person. Exposure to sewage is a risk factor for ASM. Unnecessary use of antibiotics was common but should be discouraged by carefully monitoring the health surveillance system.