Journal of Environmental Protection and Ecology 14, No 3, 1132–1139 (2013) Public health
Environmental Risk Factors for Influenza AH1N1 among Children in South-east Romania S. C. Cambreaa,b, St. Halichidisa,b*, C. M. Mihaib, D. S. Carpa, R. M. Stoicescuc, O. C. Arghirb Constanta Clinical Infectious Diseases Hospital, Constanta, Romania Faculty of Medicine, ‘Ovidius’ University, Constanta, Romania c Faculty of Pharmacy, ‘Ovidius’ University, Constanta, Romania E-mail:
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b
Abstract. The study purpose was to assess the strategies for preventing the environmental conditions and further preventive measures for influenza AH1N1 in children. Retrospective study was carried out among patients less than 18-year old with influenza symptoms hospitalised between November 1st, 2009 and April 31st, 2013, in Constanta Clinical Infectious Diseases Hospital. Patients were analysed by demographic characteristics with respect to underlying medical conditions. Influenza B virus was reported in 16 cases and AH1N1 type in rest of 106 and, particularly, in urban area (83% versus 37.5%; odd ratio (OR) = 8.15; 2.33 < OR < 29.5; CI 95%; relative risk (RR) = 2.21; 1.17 < RR < 4.19; p < 0.00006). The prevalence of A influenza increased according to age, 71.4% among kinder garden children, 87.8% in primary school aged children, and 93.4% in high school students. The median age of 122 patients was 14 ± 4.528 years. The most common complications were viral myositis (n = 27) and bacterial pneumonia (n = 67), associated with acute respiratory failure (n = 13). Only one death was registered among influenza AH1N1. Influenza AH1N1 illness was more prevalent than B (86.9% versus 13.1%). The identified environmental risks of influenza AH1N1 were urban settings (p < 0.00006), and the absence of vaccination among pupils and their parents (p < 0.03). Keywords: influenza, environmental risk factors, children, air pollution, pneumonia.
AIMS AND BACKGROUND The global epidemiology of human infection with pandemic influenza AH1N1 virus indicates that the age distribution of rates of hospitalisation and mortality is different than that for seasonal influenza, which predominantly occurs among elderly persons1,2. Risk factors for severe AH1N1 disease3–7 have been reported to be similar to those identified for complicated seasonal influenza2. A higher risk of severe complications from influenza AH1N1 virus infection has also been reported in overweight patients and among different populations3,8,9. The effective management of seasonal influenza continues to constitute a major concern throughout the public health community10. A key issue facing the public *
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health community includes the development of strategies for reducing the spread and effects of influenza AH1N1. The effective implementation of strategies for mitigating these issues necessitates an understanding of the relationship between the spread of influenza and its debilitating effects on humans as well as the identification of factors associated with morbidity resulting from influenza infection. By predominantly exploring individual, and spatial demographic characterisations, recent research on the influenza AH1N1 has overlooked underlying causes of hospitalisation at the ecological level1,3. Despite their significance, individual level studies are largely remedial in approach, place-based policy relevant factors that are increasingly important through emerging infectious diseases11,12. Although ethnicity and age are important factors associated with influenza hospitalisations, their occurrence may stem from other underlying mechanisms including environmental factors such as transportation and land use or be dependent on socioeconomic factors such as education13,14. Additionally, other spatial factors associated with influenza hospitalisations are significant, yet often disregarded, aspects of influenza studies that could provide efficient disaster mitigation and response strategies15. The identification of associated ecological factors will increase our understanding of human illness during an influenza pandemic, having direct implications for informing disaster mitigation and response strategies. EXPERIMENTAL For each child with symptoms suggestive of flu was taken a nasal and pharyngeal swab collected into virus transport medium. Extraction was performed manual using INVITROGENE kits. For amplification and detection we use a real-time reverse transcriptase-polymerase chain reaction PCR (rRT-PCR) Stratagene. For all 122 patients positivity index was 100%. The influenza AH1N1 in Constanta retained the conspicuous epidemic bell-shaped curve often characteristic of pandemics. Case patients were selected by physicians for medical chart review and data abstraction to reflect the monthly distribution of children cases per hospital. Data extraction was performed retrospective using a standardised form to collect data about demographic characteristics, underlying chronic medical conditions, preventive measures and outcomes. Informed consent was obtained from patient parents in compliance with the principles of the Helsinki Declaration, at the moment of admission to the hospital. The study was approved by the local Committee of Ethics of the Constanta Clinical Infectious Diseases Hospital. Beginning on 1st November, 2009, all laboratory-confirmed cases of AH1N1 infection were reported to the Constanta Clinical Infectious Diseases Hospital. During the first 4 months of the pandemic, all confirmed patients, regardless of the clinical severity of their illness, were admitted to the hospital and placed in 1133
isolation for containment purposes16. A confirmed case patient was defined as a patient who was hospitalised for at least 24 h with an acute influenza-like illness (temperature > 38oC either with cough or sore throat) and 2009 AH1N1 virus infection testing of respiratory specimens. Laboratory testing and confirmation of case patients are similar to those used by Yu et al.16 Confirmed patients were classified as having severe illness if they were admitted to an intensive care unit (ICU) or died, and they were classified as having no severe illness if they were alive and had not been admitted to an ICU by the end of the study period. Statistical evaluation was performed by the software EPI INFO version 3.5.1. Three subsets of the study population were analysed separately to assess risk factors associated with severe illness using multivariable logistic regression. Prevalence and mortality rates were also calculated. RESULTS AND DISCUSSION In this study, we presented the epidemiological and clinical characteristics of identified cases less than 18-year old, who were hospitalised with laboratoryconfirmed AH1N1 infection across south-eastern geographical area of Romania from 1st November, 2009 through 31st April, 2013 and we analyse potential risk factors associated with severe illness. During above mentioned period a total of 122 confirmed patients with influenza were admitted in Constanta Clinical Infectious Diseases Hospital from south-eastern part of Romania. Most cases of seasonal influenza are occurring between late December and early February (n = 83/122; 68%). None of the 122 patients or their parents had been yearly vaccinated. The distribution of cases consists in 85 boys and 37 girls, with 98 children from urban settings (80.3%) (Table 1). 20 cases were diagnosed in kindergarten children, 29 in school-aged children and 57 in high school students. Influenza B virus was reported in 16 cases and AH1N1 type in rest of 106 and, particularly, in urban area (n+88/106; 83% versus 6/16; 37.5%; OR = 8.15; 2.33
