Respiratory Syncytial Virus lethality: 16 years’ experience in a Pediatric Hospital.

Background: Respiratory Syncytial Virus (RSV) is the main agent that causes Acute Lower Respiratory Tract Infection (ALRI) in children. The objective of this study was to describe lethality factors associated to RSV infection.

Methods: Prospective, Cross sectional study of patients admitted for ALRI, 2000-2015. Virological diagnosis of respiratory virus: RSV, adenovirus (AV), influenza (IF) and parainfluenza (PIV) was made by fluorescent antibody assay of nasopharyngeal aspirates or real time-PCR.

Results: From a total of 14,044 patients included, 38.2 %( 5374) had positive samples; RSV was predominant (80.3 %, 4320/5374) all through the study period, followed by IF: 7.3%, PIF 6.4% and AV:4.3%;) RSV had a seasonal epidemic pattern (viral activity onset and offset: 19-35 epidemiological weeks) coinciding with the months of lowest average temperature. The median of age of RSV cases was 7 months (0-216 months); 56.6% were males; the most frequent clinical feature: bronchiolitis 61%; comorbidity was found in 41.4%; 5% were malnourished, 13.8% born preterm and 1.9% immunosuppressed; 23.4% had complications, 6.5% nosocomial infections. Lethality was 1.9 % (80/4276).

Regarding fatal cases: median age was 5 months(1-180 months), 51.3%<6 months, 27.5%<3 months; the most frequent clinical feature was pneumonia 52.5%; 66.2% had comorbidities: recurrent obstructive bronchitis(52.8%), congenital heart disease(34%), chronic neurological disease(24.5%); 20% were malnourished, 25% born preterm and 2.5% immunosuppressed; most frequent complications were: 81.3% respiratory distress, 46.8% nosocomial infections, 34.6% sepsis.

Moderate to severe malnourishment OR 2.06(1.04-4.08) p=0.03, congenital cardiopathy 3.05(1.48-6.29) p<0.01 and the presence of chronic neurological disease OR 2.79(1.28-6.04) p<0.01 were the independent predictors for VSR lethality.

Conclusion: RSV showed an epidemic pattern (May-July) and it affected mostly young children. RSV lethality was more associated with malnourishment, congenital cardiopathy and chronic neurological disease.