Clinical and epidemiologic features of mumps meningoencephalitis and possible vaccine-related disease.

All cases of mumps meningoencephalitis diagnosed at our institution during the past 15 years were reviewed. There were 24 cases, 16 between 1973 and 1977, 3 between 1978 and 1985 and 5 in 1986 to 1988. Four of the recent cases occurred 19 to 26 days after receipt of a new mumps vaccine (Urabe Am 9 strain) released in Canada in 1986. The remaining 20 cases were clustered in winter and spring. The average age was 6.2 years and the ratio of males to females was 5:1. Clinical presentations were fever (90%), vomiting (90%), meningismus (70%), headache (65%), parotitis (50%) and seizures (30%). The mean cerebrospinal fluid white blood cell count was 513/mm3 (lymphocyte predominance); 55% of patients had a cerebrospinal fluid protein level of greater than 0.4 g/liter, and the cerebrospinal fluid:blood glucose ratio was greater than 0.4 in all. Two patients had adverse sequelae. The clinical and laboratory features of these cases were not significantly different from the vaccine-associated cases.