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Viral shedding patterns of children with influenza B infection
Insights
During influenza B epidemics, children shed significant amounts of virus for up to four days. Higher viral shedding correlated with more severe illness, suggesting a link between virus quantity and disease severity.
Area of Science:
- Virology
- Pediatrics
- Epidemiology
Background:
- Quantitative shedding patterns of influenza B virus in children are not well-described.
- Understanding viral shedding is crucial for managing infectious disease outbreaks.
Purpose of the Study:
- To prospectively determine the quantitative shedding patterns of influenza B viral infection in ambulatory children.
- To correlate viral shedding with clinical presentation and severity.
Main Methods:
- Prospective follow-up of 43 ambulatory children during an influenza B epidemic.
- Quantification of influenza B virus in nasal washes using log10 50% tissue culture infective doses/ml.
- Assessment of clinical illness spectrum, including influenzalike illness, upper respiratory tract infection, croup, and myositis.
Main Results:
- High viral shedding rates observed: ≥93% shed virus on days 1-3, and 74% on day 4.
- Average peak viral shedding was 4.0 log10 TCID50/ml, declining to 2.4 log10 TCID50/ml by day 4.
- Viral shedding quantities significantly correlated with illness severity and fever score.
Conclusions:
- Clinical illness severity in influenza B may be directly related to the virus's cytotoxic effects.
- Higher viral shedding correlates with increased disease severity, potentially impacting transmissibility.
- Findings provide insights into influenza B pathogenesis and transmission dynamics in pediatric populations.
Abstract:
During an epidemic of influenza B, 43 ambulatory children were prospectively followed to determine the quantitative shedding patterns of influenza B viral infection, because these have not been previously described. The spectrum of illness included 74% with a typical influenzalike illness, 7% with an afebrile infection of the upper respiratory tract, and 19% with croup. Mild myositis occurred in 21%. For the first three days of illness, greater than or equal to 93% of the children shed virus, and 74% shed on day 4. The average peak quantity of virus shed in the nasal wash was 4.0 log10 50% tissue culture infective doses/ml(range, 1.5-6.0), which gradually declined over four days to 2.4 log10 50% tissue culture infective doses/ml. The quantities of virus shed correlated significantly with severity of illness and fever score, but not with sex, type of illness, or occurrence of myositis. These results suggest that the degree of clinical illness may be directly related to the cytotoxic effects of the virus and to the transmissibility of the disease.