During the autumn of 1992, Western Australia experienced a large viral 
meningitis outbreak of dual aetiology. Of the 161 cases, 64% were children under 
15 years of age, with the highest notification rate being in children less than 
5 years of age. Echovirus 9 caused 41% of cases and occurred mainly in the 
metropolitan areas of Western Australia whereas echovirus 6, which caused 37% of 
cases, was more widespread. An enterovirus was cultured from 70% of CSF 
specimens, 88% of faecal specimens and 68% of upper respiratory tract specimens. 
High CSF white cell counts and neutrophil predominance were common. Seven cases 
had normal CSF white cell counts even though an enterovirus was isolated from 
the CSF. Therefore, the CSF findings were of restricted value in excluding viral 
meningitis, and did not reliably distinguish between bacterial and viral 
meningitis.