Prospective population-based study of viral lower respiratory tract infections in children under 3 years of age (the PRI.DE study).

Population-based incidence data from Europe on the disease burden of lower respiratory tract infections (LRTI) due to respiratory syncytial viruses (RSV), parainfluenza viruses (PIV) and influenzaviruses (IV) are lacking, especially with respect to the disease burden. In a 2-year prospective multicentre study of children aged <3 years in Germany, we registered population-based cases as outpatients (n=2386), inpatients (n=2924), and nosocomially-acquired (n=141). Nasopharyngeal secretions were tested for viral RNA. The annual incidence for physician visits per 100 children for all LRTI was 28.7, RSV 7.7, PIV 3.8 and IV 1.1. Annual hospitalisation rates per 105 children were for all LRTI 2941, RSV 1117, PIV 261 and IV 123. Annual nosocomial cases per 105 hospital days were for all LRTI 79, RSV 29, PIV 9 and IV 1.5. All five children (0.27%) who died had an underlying disease and four were nosocomially acquired. Conclusion: Hospitalisation rates due to lower respiratory tract infections in healthy children were similar to those reported elsewhere; the rates for outpatient visits were approximately ten times higher.