The Analysis Of Relationgship Between Influenza And Atmospheric Ambient And The Establishment Of Influenza-Like-Illness Rates Forecasting Model

When the paper is nearing completion,an influenza pandemic is global spreading,which started in Mexico in April of 2009,and sounded a warning for humanity to fence out influenza illness again.As the first kind of global monitoring respiratory infectious disease,influenza not only cause a large number of population morbidity and mortality but also a tremendous economic loss and social burden.China is one of the countries with high incidence rate of influenza,the strains which caused 1957,1968 and 1977,three world-wide pandemic influenza were first discovered in China,In 1999,2003 and 2008,an influenza pandemic caused by a new subtype of influenza virus broke out in Hong Kong,Shenzhen City lies besides Hong Kong and Macao,people from each side move frequently and the influenza virus are vitality year-round,so there is a high incidence of influenza in the crowd.Shenzhen was chosen as one of the focus of the monitoring of influenza by the National Influenza Center of China in 1994,so it is of great practical significance to study the influenza in Shenzhen City.This article have collected Influenza-Like-Illness Rates material in Shenzhen from 2003 to 2007 year and the corresponding atmospheric environment material systematically for the first time,made a detailed analysis of the epidemiological characteristics of influenza in Shenzhen, focused on the relation of seasonal incidence of influenza characteristics with meteorological conditions and air quality,carried on the example diagnostic analysis to Shenzhen influenza at the very time when the Hong Kong influenza pandemic broke out in 2008,and established Shenzhen influenza's forecasting model using the statistical method and the Support Vector machines method finally,made the prediction accuracy test and comparison of independent samples.Accessed to a number of important research results,as the follow:(1)The influenza illness in Shenzhen happens throughout the year,its pandemic time is in March to September,the non-popular time is October to February of next year, Influenza-Like-Illness Rates in summer is much higher than other seasons;By the influence of Asian H7N1 influenza pandemic,ILI%of 2003 and 2004 is higher than the following three years; At the same time,it appears a trend that the seasonal peaks of influenza in Shenzhen,especially the first peak is moving to the summer,it also appears that a number of small peaks gradually gathering into a main peak.(2) It has been found ILI%in Shenzhen associate with aqueous vapor tension,absolute humidity,relative humidity,atmospheric temperature and atmospheric pressure closely. Simultaneously discovered that the absolute content of water vapor in air influence influenza mostly.(3) Meteorological factors' influence on the influenza exists an obvious leading effect.The average relative humidity,minimum relative humidity have strongest associations with ILI%in lag two weeks,as absolute humidity and average wind speed lag in three weeks,Week change temperature lag in four weeks.The lag effect of Meteorological factors on influenza has good meaning of forecasting.(4) By the use of wavelet analysis of influenza time series in Shenzhen found besides the main cycle of influenza seasonal changes,there are two other outbreak cycles of local influenza epidemic,which were 70 weeks and 30 weeks.The seasonal influenza cycle mainly influence by various climate elements and acid rain.At the same time,its 30 weeks cycle mainly be influenced by relative humidity,temperature and rainfall,and 70 weeks cycle by the impact of atmospheric pressure.(5) SO₂,PM₁₀ and ILI%showed a significant anti-correlation,that means SO₂ and PM₁₀ is conducive to inhibit influenza pandemic,SO₂ and PM₁₀ influence influenza most significantly one week ahead,which has better forecasting significance.Acid deposition has an effect against influenza viruses,which could prevent the spread of influenza among the crowd.The season characteristic of acid rain has a certain impact on the season pandemic feature of influenza.(6) The critical range of atmospheric environment elements has been established,which has been proved by special analysis.The results show that there is a possibility to occur the seasonal peaks of influenza in the conditions of the vapor pressure from 23hPa to 29hPa, absolute humidity from 2.0 mg/m³ to 2.3mg/m³,the average relative humidity from 60%to 80%, average temperature between 25℃to 30℃,and the average atmospheric pressure is lower than 1008hPa.At the same time,ILI%will increase as the increase of temperature and humidity when the maximum temperature lower than 30℃,minimum temperature lower than 25℃,and the minimum relative humidity less than 60%.ILI%will decrease as the increase of temperature and humidity when the maximum temperature exceeded 30℃,the minimum temperature above 25℃and the minimum relative humidity more than 60%.More than that,the influenza peak has more possibility to happen as the climate situation changes acutely,such as humidity from lower to high,and temperature,pressure,precipitation or other meteorological factors dramatic ups and downs.(7) The forecasting model of ILI%in Shenzhen has been established by Support Vector Machine method,the results has been compared with statistical forecasting model.It has been found that SVM forecasting model has a better forecast effect than statistical forecasting model, which proves SVM method could be used in the field of illness forecasting with satisfactory prediction.