Seasonality of long term wheezing following respiratory syncytial virus lower respiratory tract infection.

BACKGROUND: It is well known that respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is associated with subsequent wheezing episodes, but the precise natural course of wheezing following RSV LRTI is not known. This study aimed to determine the continuous development of wheezing following RSV LRTI in children up to the age of 3 years. METHODS: A prospective cohort study was performed in 140 hospitalised infants with RSV LRTI. Continuous follow up data were obtained with a unique log in which parents noted daily respiratory symptoms. RESULTS: A marked decrease in wheezing was seen during the first year of follow up. The burden of wheezing following RSV LRTI was observed during the winter season. Signs of airflow limitation during RSV LRTI were strongly associated with wheezing during the follow up period. Total and specific serum immunoglobulin E levels, patient eczema, and parental history of atopy were not associated with wheezing. CONCLUSIONS: Airway morbidity following RSV LRTI has a seasonal pattern, which suggests that viral upper respiratory tract infections are the predominant trigger for wheezing following RSV LRTI. There is a significant decrease in airway symptoms during the first 12 months after admission to hospital. Simple clinical variables, but not allergic risk factors, can predict the development of wheezing following RSV LRTI.

Local interferon-gamma levels during respiratory syncytial virus lower respiratory tract infection are associated with disease severity.

To investigate the role of cell-mediated immunity during respiratory syncytial virus (RSV) infection, interferon (IFN)-gamma and interleukin (IL)-10 levels in nasopharyngeal secretions were measured in infants with lower respiratory tract infection (LRTI) caused by RSV. A novel technique was used to measure in vivo cytokine levels in nasopharyngeal aspirates (NPAs). Cytokine levels in the NPAs of 17 mechanically ventilated infants and 43 nonventilated hospitalized infants were compared. As expected, mechanically ventilated infants were significantly younger than nonventilated infants (7 vs. 14 weeks). IFN-gamma levels were above the limit of detection in the NPAs of 3 (18%) mechanically ventilated infants and in the NPAs of 26 (60%) nonventilated infants. IL-10 levels in the NPAs of mechanically ventilated and nonventilated infants were comparable. It is hypothesized that maturation-related mechanisms have a key role in the development of RSV LRTI that results in mechanical ventilation.

Airflow limitation during respiratory syncytial virus lower respiratory tract infection predicts recurrent wheezing.

BACKGROUND: Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is frequently followed by recurrent wheezing. Thus far no clinical risk factors have been identified to predict which infants will have wheezing episodes subsequent to RSV LRTI. OBJECTIVE: To determine clinical predictors for airway morbidity after RSV LRTI. METHODS: In a 1-year follow-up study we investigated the predictive value of auscultatory findings characteristic of airflow limitation (wheezing) during RSV LRTI for subsequent airway morbidity. Clinical characteristics, including the presence or absence of signs of airflow limitation, of hospitalized infants with RSV LRTI were prospectively recorded during 2 winter epidemics. During a 1-year follow-up period parents of 130 infants recorded daily airway symptoms. OUTCOME MEASURE: Recurrent wheezing defined as > or = 2 episodes of wheezing. RESULTS: Signs of airflow limitation during RSV LRTI were absent in 47 (36%) infants and present in 83 (64%) infants. Recurrent wheezing was recorded in 10 (21%) infants without signs of airflow limitation and in 51 (61%) with signs of airflow limitation during initial RSV LRTI (relative risk, 0.29, P < 0.001). In a multiple logistic regression model, airflow limitation during initial RSV LRTI proved independent from other clinical parameters, including age, parental history of asthma and smoke exposure. CONCLUSIONS: A sign of airflow limitation during RSV LRTI is the first useful clinical predictor for subsequent recurrent wheezing.