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Epidemiology of encephalitis in children. A prospective multicentre study
M Koskiniemi1, M Korppi, K Mustonen
1Department of Virology, Haartman Institute, Helsinki University, Finland.
Insights
Pediatric encephalitis etiology has shifted due to vaccines, with varicella zoster and enteroviruses increasing. While some viral causes declined, new microbes like Chlamydia pneumoniae emerged, impacting child encephalitis diagnosis.
Area of Science:
- Pediatric Infectious Diseases
- Neurovirology
- Epidemiology
Background:
- Acute encephalitis in children presents a significant public health challenge.
- Understanding the changing etiological landscape is crucial for effective management.
Purpose of the Study:
- To investigate the incidence and microbial causes of acute encephalitis in children.
- To identify shifts in the etiological spectrum of pediatric encephalitis over time.
Main Methods:
- Population-based surveillance of acute encephalitis cases in children aged 1 month to 15 years over a 2-year period (1993-1994).
- Microbial diagnosis was established through laboratory testing and clinical suspicion.
- Incidence rates were calculated per 100,000 child-years.
Main Results:
- 175 cases of acute encephalitis were identified, with an overall incidence of 10.5/100,000 child-years.
- Microbial causes were identified in 63% of cases, with varicella zoster, respiratory, and enteroviruses being most common.
- Mumps, measles, and rubella virus-associated encephalitis decreased, while varicella zoster, respiratory viruses, enteroviruses, Chlamydia pneumoniae, and HHV-6 increased, particularly in younger children.
Conclusions:
- Vaccination programs have altered the spectrum of encephalitis in children, reducing certain viral causes.
- The overall incidence of encephalitis remains stable, attributed to the increased frequency of other established and novel microbial agents.
Unlabelled:
We found 175 cases with acute encephalitis in a population of 791,712 children aged 1 month-15 years during a 2-year surveillance period in 1993-1994. The overall incidence was 10.5/100,000 child-years with the highest figure in children < 1 year of age, 18.4/100,000 child-years. The microbial diagnosis was considered proven or suggested in 110 cases (63%); varicella zoster, respiratory and enteroviruses comprised 61% of these, and adeno, Epstein Barr-, herpes simplex and rota viruses comprised 5% each. A clearcut change seems to have occurred in the aetiology of encephalitis. Mumps, measles, and rubella virus associated encephalitides have been almost eliminated. Varicella zoster, respiratory, and enteroviruses have increased in frequency and occur in younger age groups. New causes were identified, especially Chlamydia pneumoniae and HHV-6. Our data should assist in making a specific diagnosis and defining appropriate antimicrobial therapy.
Conclusions:
The spectrum of encephalitis in children has changed due to vaccination programs. The incidence, however, appears to be about the same due to increasing frequency of other associated old and new microbes.