Defining the timing of respiratory syncytial virus (RSV) outbreaks: an epidemiological study

Elena Terletskaia-Ladwig,Gisela Enders,Gunnar Schalasta,Martin Enders

doi:10.1186/1471-2334-5-20

Abstract

BackgroundSeasonal RSV infections occur every year and affect particularly children under six months of age. Passive immunoprophylaxis with monoclonal antibody Palivizumab is recommended in the period with high risk of RSV infection. This study aims to define the period for the southern part of Germany (Stuttgart area).MethodsEpidemiological analysis of the RSV situation in southern Germany from 1996 to 2004 and comparison of results with literature was made. The respiratory tract specimens were sent in for the detection of RSV mainly by paediatric clinics. Detection of RSV was carried out mainly by real-time RT-PCR or by ELISA "Pathfinder". RSV outbreaks were depicted as an absolute number and as a percentage of RSV diagnoses in a month. Onsets, offsets, peaks, duration and severity of RSV seasons were defined and analysed.ResultsAn early season with strong RSV activity (early-high phase) was followed by a weaker late season (late-low phase) in a regular biennial rhythm. However, onsets, offsets and durations of outbreaks varied significantly from year to year. RSV epidemics in southern Germany were found to oscillate in an antiphase with RSV epidemics in Finland and Sweden.ConclusionThe long-term regular biennial rhythm allows predicting whether the next outbreak will be late or early and whether RSV activity will be strong or weak. Not foreseeable, however, is the precise time of increase and decrease of RSV activity. Moreover, the regular seasonal pattern may be disrupted by irregular outbreaks. Thus, activity of RSV has to be monitored every year to define the period with high risk of infection.

Highlights

Seasonal Respiratory syncytial virus (RSV) infections occur every year and affect children under six months of age
In view of the relatively low risk of RSV rehospitalisation among premature infants and high costs of immunoprophylaxis, additional individual risk factors and especially the local epidemiologic situation have to be considered in the case of Synagis®-administration [1,2,3]
In Europe, regular biennial patterns of RSV epidemics were described in which a weaker late season was followed by a more severe early season [7,8,9,10,11]

Summary

Introduction

Seasonal RSV infections occur every year and affect children under six months of age. Passive immunoprophylaxis with monoclonal antibody Palivizumab is recommended in the period with high risk of RSV infection. A humanized monoclonal antibody palivizumab (Synagis®, Abbott) was licensed in September 1999 in the European Union for passive immunoprophylaxis of RSV. In view of the relatively low risk of RSV rehospitalisation among premature infants and high costs of immunoprophylaxis, additional individual risk factors and especially the local epidemiologic situation have to be considered in the case of Synagis®-administration [1,2,3]. RSV epidemics occur seasonally and last from four to six months. North of the equator the peak incidence of disease is observed from December to April [4,5,6]. The discovery of a regular pattern of RSV epidemics seemed to allow the prediction of outbreaks

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