The interplay between illness, time use, mobility and social contact behaviour and its relevance for infectious disease transmission.

Abstract

To gain knowledge on the effects of possible intervention strategies, realistic mathematical models of infectious disease transmission are necessary. Social contact behaviour, which is relevant for spreading of infections through the respiratory route, has been shown to provide valuable information in estimating the transmission parameters in said mathematical models. Throughout this thesis, we discuss various factors influencing social contact behaviour and therefore possibly the spread of infectious diseases through the respiratory route. An introduction to the basic concepts and the data is provided in Chapters 1 and 2. In Chapter 3, the focus is on changes in contact behaviour due to illness. To start with, we present results from a social contact survey aiming at quantifying the changes in social contact behaviour as a result of illness. This information is then used in a mathematical model to better quantify the spread of (a)symptomatic infections in the context of the A/H1N1pdm 2009 epidemic in the UK. Additionally, we present results of a pilot study that aimed to quantify the impact of seasonal influenza (influenza-like-illnesses) and chronic diseases on social contact behaviour. In Chapter 4, we present a variety of research topics: (1) effects of weather conditions on social contact behaviour; (2) human-animal interactions and the relative probability for a major zoonotic outbreak; and (3) within-household networks enabling to study the random mixing assumption within households. Finally, in Chapter 5, we present two studies focusing on mobility and social contact dispersal of which the first one describes the spatial dispersion of social contacts while the second one describes a metapopulation model which accounts for changes in mobility and social contact behaviour. The results in this thesis provide information to improve models of infectious disease spread, thereby enabling better understanding on the effects of various intervention strategies.