virus, obtained from a swab of the orifice of Stenson's duct and from the CSF, was identified as the vaccine strain on the basis of the morphology of the cytopathic effect but not by molecular analysis. Fescharek and colleagues (1990) described the isolation of mumps virus from two patients with meningitis reported to the pharmaceutical firm Behringwerke AG in the former West Germany. The mumps vaccine administered was Jeryl Lynn (that used in the United States), but identification of the virus as wild-type or vaccine strain was not attempted.
Eleven cases of meningitis following receipt of MMR in the United States (the Jeryl Lynn strain of mumps vaccine) reported in VAERS (submitted between November 1990 and July 1992) were examined by the committee. In no case was the strain identified or the virus isolated. The latencies from vaccination to symptoms ranged from 3 days to 2 weeks. In some patients the clinical symptoms seemed supportive of a diagnosis of meningitis, but intercurrent infections were seen in two of the patients, insufficient information was available for three patients, and encephalopathy was possible for another patient.
There is strong biologic plausibility that mumps virus could cause aseptic meningitis. Wild-type mumps virus clearly does so. Isolation of the virus and typing by molecular biologic techniques as the vaccine strain of mumps virus from patients who developed aseptic meningitis following immunization with mumps vaccine provide evidence of a causal relation. This relation is firmly established for the Urabe strain. The incidence appears to be approximately 1 case per few thousand vaccine recipients. The matter is unclear with regard to the Jeryl Lynn strain (that used in the United States), because in the sole reported case in which the virus was identified as the "vaccine strain," the isolated virus was typed by the older morphologic technique and not by molecular analysis. In the two other published cases of Jeryl Lynn-associated mumps meningitis, the virus was not typed as the vaccine or wild-type strain. VAERS contains several reports of what probably is meningitis after administration of Jeryl Lynn mumps vaccine-containing preparations, but the reports do not describe virus isolation or typ-