mining the causal relation between measles and mumps and encephalopathy and encephalitis, are lacking. No conclusive evidence of the occurrence of encephalopathy or encephalitis resulting from the administration of measles vaccine was identified. There are no data regarding the occurrence of encephalopathy following administration of monovalent mumps vaccine. It is therefore not possible to implicate specifically either the measles or mumps component of MMR.

Conclusion

The evidence is inadequate to accept or reject a causal relation between measles or mumps vaccine and encephalitis or encephalopathy.

ASEPTIC MENINGITIS

Clinical Description

Aseptic meningitis is defined as an inflammation of the meninges associated with pleocytosis of the CSF. In the early stage of aseptic meningitis polymorphonuclear leukocytes predominate, but within 8 to 16 hours this changes to a predominance of mononuclear cells. There may be some elevation of protein, but in general, the glucose level is normal. In patients with aseptic meningitis associated with mumps, there may be hypoglycorrhachia. Bacterial cultures are negative. The description of aseptic meningitis in the wake of mumps vaccine administration follows this pattern, except that hypoglycorrhachia was not mentioned in the reports.

The yearly incidence of aseptic meningitis for the years 1950 to 1981 in Olmsted County, Minnesota, was 10.9 per 100,000 people (Nicolosi et al., 1986). The annual incidence was markedly higher in children less than age 1 year (82.4 per 100,000) and slightly higher in children between ages 1 and 4 years (16.2 per 100,000) and in children between ages 5 and 9 years (18.8 per 100,000).

History of Suspected Association

Mumps disease is clearly associated with aseptic meningitis. The committee was charged with investigating a possible causal relation between only mumps vaccine and aseptic meningitis.



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