Epidemics of aseptic meningitis due to enteroviruses following national immunization days in Bahrain

We report two successive epidemics of aseptic meningitis due to enteroviruses (EV) observed after national immunization days against polio. Meningitis due to echovirus 30 occurred from July 1995 to the end of January 1996, mostly among children aged 0-12 years (95.1% of cases), and meningitis due to echovirus 4 occurred from May 1996 to the end of September 1996 in the same age group. There were 286 and 169 cases, respectively. Specimens from several representative cases were sent to the WHO Collaborating Center for Virus Reference and Research Laboratory for serological testing and virus detection, including polymerase chain reaction (PCR) studies. Using those tests, evidence of echovirus 30 infection was found in 44% of the children who were sampled during the first epidemic and 45.5% during the second. During echovirus 30 and echovirus 4 epidemics, a similar decline in the age-specific attack rate from 19.1/10,000 and 10.1/10,000 population aged 12 years to 2.4/10,000 and 3.6/10,000 population aged 13 years was observed, respectively.