Transmission of Novel Influenza A(H1N1) in Households with Post-Exposure Antiviral Prophylaxis

BACKGROUND: Despite impressive advances in our understanding of the biology of novel influenza A(H1N1) virus, little is as yet known about its transmission efficiency in close contact places such as households, schools, and workplaces. These are widely believed to be key in supporting propagating spread, and it is therefore of importance to assess the transmission levels of the virus in such settings. METHODOLOGY/PRINCIPAL FINDINGS: We estimate the transmissibility of novel influenza A(H1N1) in 47 households in the Netherlands using stochastic epidemic models. All households contained a laboratory confirmed index case, and antiviral drugs (oseltamivir) were given to both the index case and other households members within 24 hours after detection of the index case. Among the 109 household contacts there were 9 secondary infections in 7 households. The overall estimated secondary attack rate is low (0.075, 95%CI: 0.037-0.13). There is statistical evidence indicating that older persons are less susceptible to infection than younger persons (relative susceptibility of older persons: 0.11, 95%CI: 0.024-0.43. Notably, the secondary attack rate from an older to a younger person is 0.35 (95%CI: 0.14-0.61) when using an age classification of <or=12 versus >12 years, and 0.28 (95%CI: 0.12-0.50) when using an age classification of <or=18 versus >18 years. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the overall household transmission levels of novel influenza A(H1N1) in antiviral-treated households were low in the early stage of the epidemic. The relatively high rate of adult-to-child transmission indicates that control measures focused on this transmission route will be most effective in minimizing the total number of infections

Development of a simulation tool to enable optimisation of the energy consumption of the industrial timber-drying process

Reducing the liquid content of green products is an important step in the manufacture of many products. Process conditions in the drying phase have significant influences on the quality of the end product and on energy consumption and required manufacturing time. Effective optimisation of the drying process requires accurate representation of the drying product and its interaction with its environment. The development of a computer simulation tool to analyse the industrial batch timber drying process is outlined. A detailed finite difference product model describing the heat and mass transfers within a plank during drying is described. It is integrated with a customised CFD code characterising the process conditions within the drying chamber. Simulation output from the integrated model is used to generate a macroscopic representation of the product in its drying environment. This representation is included as a component in a modular industrial installation simulation environment. Analysis with this global model can lead to optimisation of energy consumption of the industrial timber drying process whilst maintaining product quality and acceptable drying duration.