Escherichia coli (E. coli) bacteria cause much disease and death worldwide. However, little is known about the mechanisms these bacteria and others use to cause disease in their hosts. Specific virulence factors - strategies and molecules that enable the bacteria to cause infection - are needed for disease to develop. The bacteria inject these virulence factors into host cells, which affect normal cellular processes. Dr. Mark Wickham is using two pathogens, E. coli and Citrobacter rodentium, as a model to research how pathogens produce disease at the molecular and cellular levels. Understanding how this process occurs will address a gap in current knowledge, thus improving health and health services, and the research results could be applicable to other disease-causing organisms.