How mathematical models have helped to improve understanding the epidemiology of infection

Mathematical models have proved to be useful tools for addressing questions about the process of infection. This is because the model allows the investigation of the mathematical link between invisible events (transmission of infection between individuals) and more visible ones (incidence of clinical infection, seroprevalence data etc.). A useful model is often one that is simple enough to provide answers that are applicable to as general a context as possible, but also complex enough so that it can address the most relevant questions. Thus, relatively simple models of viral (or hospital acquired-) infection were used to establish the existence of critical thresholds of immunisation (or antibiotic usage) coverage, although more complex models were needed for the investigation of the impact of infection control practices within more specific contexts. Mathematical models have the potential to elucidate key determinants of the epidemiology of infectious disease arising in infants nursed in neonatal intensive care units. (c) 2007 Elsevier Ireland Ltd. All rights reserved.