Analysis of biennial outbreak pattern of respiratory syncytial virus according to subtype (A and B) in the Zagreb region |
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Authors: | Gordana Mlinaric‐Galinovic Irena Tabain Tamara Kukovec Gordana Vojnovic Jadranka Bozikov Jasna Bogovic‐Cepin Irena Ivkovic‐Jurekovic Ivica Knezovic Goran Tesovic Robert C Welliver |
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Institution: | 1. Department of Virology, Croatian National Institute of Public Health and University Medical School of Zagreb,;2. Department of Virology, Croatian National Institute of Public Health,;3. Institute of Public Health Varazdin, Varazdin, Croatia;4. Department of Medical Statistics, Epidemiology and Medical Informatics, A.Stampar School of Public Health, Medical School University of Zagreb,;5. Children's Hospital Zagreb, ‘Sestre milosrdnice’ University Hospital Centre,;6. University Hospital for Infectious Diseases ‘Dr Fran Mihaljevic’,;7. University Medical School of Zagreb, Hospital for Infectious Diseases ‘Dr Fran Mihaljevic’, Zagreb,;8. Division of Infectious Diseases, Department of Pediatrics, Children's Hospital, Oklahoma University Health Sciences Center, Oklahoma City, Oklahoma, USA |
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Abstract: | Background: The epidemic pattern of respiratory syncytial virus (RSV) in Croatia is biennial. In order to determine if the circulation of different RSV subtypes affects the outbreak cycle, the aim of the present study was to analyze the epidemic pattern of RSV in children in Croatia (Zagreb region) over a period of 3 consecutive years. Methods: The study group consisted of 696 inpatients, aged 0–5 years, who were hospitalized with acute respiratory tract infections caused by RSV, in Zagreb, in the period 1 January 2006–31 December 2008. The virus was identified in nasopharyngeal secretions using direct immunofluorescence. The virus subtype was determined on real‐time polymerase chain reaction. Results: Of 696 RSV infections identified in children, subtype A virus caused 374 infections, and subtype B, 318. Four patients had a dual RSV infection (subtypes A and B). The period of study was characterized by four epidemic waves of RSV infections: the first, smaller, in the spring of 2006; the second, larger, in December 2006/January 2007; the third in spring 2008, followed by a fourth outbreak beginning in November of 2008. The biennial virus cycles were persistent although the predominant RSV subtype in the first two epidemic waves was subtype B, and in the second two it was subtype A. Conclusion: Over a 3 year period of observation, the biennial RSV cycle in Croatia cannot be explained by a difference in the predominant circulating subtype of RSV. Other unknown factors account for the biennial cycle of RSV epidemics in Croatia. |
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Keywords: | acute respiratory infection biennial cycle bronchiolitis pneumonia respiratory syncytial virus types A and B |
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