The descriptive epidemiology of severe lower respiratory tract infections in children in Kiel, Germany

Background: Lower respiratory tract infections (LRI) inflict a high burden of disease in children worldwide. Longitudinal, descriptive epidemiological data on different forms of LRI are urgently needed to differentiate this burden, compare population-based incidence rates between countries and to recognize trends. Patients and Methods: From July 1996 to June 2000, all children hospitalized with LRI, i.e. laryngo-tracheo-bronchitis (LTB), bronchitis, wheezing bronchitis-bronchiolitis (WBB), broncho-pneumonia and pneumonia, in the municipal area of Kiel, Schleswig-Holstein, Germany, were analyzed by cross-sectional studies. Naso-pharyngeal aspirates (NPA) were analyzed by an in-house 9-valent multiplex-RT-PCR. Results: In the 4-year observational period, 1072 children aged 0 to 16 years (median 23 months) were hospitalized with LRI: 12% (median 28 months) with LTB, 11% (median 17 months) with bronchitis, 28% (median 13 months) with WBB, 26% (median 26 months) with broncho-pneumonia and 22% (median 47 months) with pneumonia. The prevalence of chronic underlying conditions (20%) and low gestational age (13%) varied in the different forms of LRI. The cumulative incidence rate of LRI rose steadily over the 4 years. The highest fraction was contributed by WBB, while pneumonia declined. The highest incidence rate ratio was attributable to respiratory syncytial virus (RSV, 0.46) and to children under 2 years of age. Conclusions: LRI, especially obstructive forms of LRI, are increasing in Germany as described earlier for the USA, UK and Sweden. The major burden is carried by children under 2 years. RSV is the single pathogen with the highest impact.