An echovirus 18-associated outbreak of aseptic meningitis in Taiwan: epidemiology and diagnostic and genetic aspects

In 2006, an outbreak of aseptic meningitis was noted in Taiwan. From January to October 2006, a total of 3283 specimens collected from patients with viral infection, including 173 cerebrospinal fluid (CSF) samples, were examined for virus isolation and identification. Overall, 339 enterovirus (EV)-positive cases were identified by virus culture: echovirus 18 (El 8) formed the majority (27.4%, 93 cases), followed by coxsackievirus B2 (13.8%, 47 cases) and coxsackievirus A2 (10.8%, 37 cases). The manifestations of the 93 E18 cases were aseptic meningitis (44.1%), viral exanthema (23.6%), acute tonsillitis (15.1%), acute pharyngitis (14.0%), acute gastritis (11.8%), herpangina (7.5%) and bronchopneumonia (5.3%). Of 107 El 8 isolates identified, 100, 62.5 and 19% were obtained following culture in RD, MRC-5 and A549 cells, respectively. E18 was identified most frequently from throat swabs (67.2%) and less frequently from stool samples (15.9%) and CSF (16.8%). The detection rate of E18 was 78.2% from CSF, 50% from stool samples and 22.9% from throat swabs. Phylogenetic relationships among the E18 strains were examined. Analysis of the partial VP1 gene showed 3.7-23.8% variation in sequence compared with sequences from GenBank and, notably, the amino acid change V152S was detected in a protruding loop within the VP1 protein. These results indicate that a genetic variant of E18 was circulating and caused an outbreak of aseptic meningitis in Taiwan in 2006.