Environmental Role of Influenza Virus Outbreaks
Influenza is one of the most significant diseases in humans, generating worldwide annual epidemics, which result in about three to five million cases of severe illness, and about 250,000 to 500,000 deaths ,Improving influenza knowledge about key epidemiological parameters such as survival, transmission and reproduction in hosts is essential to upgrade surveillance network and to develop more accurate predicting models. Better epidemic predictions would set up more appropriate public health prevention and intervention strategies.1 Epidemics occur mainly during the winter season months in temperate countries, unlike in tropical and sub-tropical countries where they generally happen during the rainy season. These differences suggest a climate impact on influenza spread.1 Climate might affect influenza diffusion (onset, duration, size) by impacting individuals’ contact rates (frequency and duration),2 population immunity and virus survival outside human body. The role of weather is however not fully understood ,despite a lot of laboratory studies of host susceptibility according to environmental conditions ,and mathematical modeling approaches analyzing the link between influenza morbidity or mortality and climatic factors Various climatic factors such as temperature, humidity, rainfalls, UV radiation, sunshine duration and wind speed might have an impact on influenza spread. In temperate countries, humidity and temperature might play an important role in influenza spread.2
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Improving knowledge about influenza transmission is crucial to upgrade surveillance network and to develop accurate predicting models to enhance public health intervention strategies. Epidemics usually occur in winter in temperate countries and during the rainy season for tropical countries, suggesting a climate impact on influenza spread. Despite a lot of studies, the role of weather on influenza spread is not yet fully understood. In the present study, we investigated that the role of environment in influenza outbreaks. A consideration that only a fraction of the human population isn’t susceptible at the beginning of a year due to immunity acquired from previous years. These results suggest that, among the six factors that appeared to be significant, only two could in fact have a real effect on influenza spread, although it is not possible to determine which one based on a purely statistical argument. Our results support the idea of an important role of climate on the spread of influenza.
