Encephalitis and aseptic meningitis, Olmsted County, Minnesota, 1950–1981: I. Epidemiology

Abstract

All cases fulfilling stated criteria for encephalitis and aseptic meningitis in Olmsted County, Minnesota, for the period 1950 through 1981 were identified. This is, to our knowledge, the first such incidence and trend study in a delineated population, providing rates per 100,000 person-years of 7.4 for encephalitis (189 cases) and 10.9 for aseptic meningitis (283 cases). These are about twelve and six times higher, respectively, than the rates reported by the Centers for Disease Control. The rates have been stable over successive 5- or 10-year periods except for a recent increase in aseptic meningitis. Both conditions were more common in the summer months, in childhood, and among males. Viral identification using conventional laboratory tests has improved with time; in the period 1970 through 1981, virus type was specified in about one-fourth of the cases. The most common agents identified were California and mumps viruses in encephalitis, and entero and mumps viruses in aseptic meningitis. Antecedent and/or concurrent infections were noted in 42 and 35% of encephalitis and aseptic meningitis cases, respectively. No case due to mumps, measles, or rubella viruses has occurred since 1972, reflecting the impact of immunizations. Recovery was reported at the end of the acute phase in 95% of patients with aseptic meningitis, and there were no deaths. Seventy-eight percent of encephalitis patients recovered completely; the case fatality rate was 3.8%. Of the encephalitis cases, 2% were diagnosed initially postmortem.

Etiology of Acute Childhood Encephalitis at The Hospital for Sick Children, Toronto, 1994–1995

“…described in 50% -72% of patients [20,25], and focal neurologDespite extensive microbiological investigation, an agent ical signs were described in 29% -42% [10,20,24,44]. A was not identified in a substantial proportion of cases.…”

“…quently encountered agent [24,27]. Since we routinely screened for arboviruses, the difference in prevalence is most The single death occurred in a 6-year-old female who was comatose at the time of admission and had status epilepticus likely secondary to geographic factors.…”

“…creased incidence during the summer, mostly cases of California encephalitis[24]. The fairly uniform distribution of patientsNeuroimaging with M. pneumoniae infection throughout the year is in keeping Fever, seizures, and focal neurological signs occurred in specific constellation of clinical findings correlated with a given NOTE.…”

Acute encephalitis in children: Progress and priorities from an Australasian perspective

“…Three recent, large, prospective studies including some children have made major contributions (see Box ). Most published childhood‐specific studies are small‐ to moderate‐sized cohorts or case series …”

Japanese encephalitis among hospitalized pediatric and adult patients with acute encephalitis syndrome in Hanoi, Vietnam 1995.

“…25 Though the majority of adults could not be diagnosed by our screening efforts, the difficulties of identifying a specific viral pathogen are also evident in the United States, where an etiology cannot be identified in 33-85% of viral encephalitis cases. [27][28][29][30][31][32] Among our patients with a confirmed diagnosis of JE, 22 had admission CSFs available for serologic testing; all of these specimens had detectable anti-JE IgM antibody. Our findings are consistent with those of a previous study, in which 73% of JE patients had diagnostic anti-JE IgM CSF elevations at admission, and 100% of the patients were positive at one week after admission.…”