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An influenza B epidemic among children in day-care
Insights
An influenza B virus outbreak in a day-care center showed high infection rates, affecting 40% of children. Many infections were asymptomatic, and frequently linked to otitis media, with no other pathogens identified.
Area of Science:
- Epidemiology
- Virology
- Pediatrics
Background:
- Influenza B virus outbreaks can significantly impact community health, particularly in settings with close contact like day-care centers.
- Understanding transmission dynamics and clinical manifestations is crucial for effective public health interventions.
Purpose of the Study:
- To investigate an outbreak of influenza B virus at a day-care center.
- To determine attack rates, identify clinical associations, and assess the role of other pathogens.
Main Methods:
- Conducted microbiological surveillance for influenza B virus, bacteria, viruses, and mycoplasmas.
- Utilized virus isolation and seroconversion to determine attack rates.
- Compared clinical and microbiological data with a previous year's data.
Main Results:
- Documented 27 influenza B virus isolations from 20 children during an outbreak from February to April 1974.
- Observed high attack rates (approximately 40%) across most age groups, with many inapparent infections.
- Noted increased incidence of otitis media and fevers >38°C during the outbreak, without identification of other dominant pathogens.
Conclusions:
- Influenza B virus can cause significant outbreaks in day-care settings with high, age-unrelated attack rates.
- Inapparent infections are common during influenza B outbreaks.
- Otitis media frequently co-occurred with influenza B infections, suggesting a potential association.
Abstract:
An outbreak of influenza virus type B infections occurred in the Frank Porter Graham Day Care Center from February to April, 1974. During the epidemic there were 27 isolations of influenza B virus from 20 children. One half of these were obtained from children who were well at the time of culturing. Attack rates as determined by virus isolation and seroconversion for most age groups approximated the 40% rate for the entire population. Clinical and microbiological data from this study were compared to those obtained in the center during the same three months in 1973. Increases in the incidence of otitis media and temperatures over 38 C were seen during the 1974 study. Intensive continuous microbiological surveillance for bacteria, viruses, and mycoplasmas failed to reveal predominance of any other potential pathogen to account for these clinical findings. The analysis permitted by the nature of this study design in a day-care setting revealed several unexpected findings: high attack rates unrelated to age; common inapparent infections; and frequent association with otitis media.