Lyme disease in a changing world: Where public health and ecology meet

The USA has suffered an epidemic of Lyme disease, which began in the late 1970s and peaked in 2002 when over 21000 cases were reported. In Canada, Lyme disease is an emerging infection due to recent expansion of the range of the tick vector Ixodes scapularis, which may in part be due to a warming climate. Here we describe how a comprehensive understanding of the ecology of I. scapularis, its hosts and the pathogens it transmits, have allowed us to predict the scope and direction of potential range expansion of Lyme disease with projected climate change. This knowledge has also allowed us to raise model-based hypotheses for how climate change may affect evolutionary processes of I. scapularis-borne microparasites and drive pathogen emergence. Together, these studies will allow us to limit the public health impact of Lyme disease and other zoonoses by prediction and early warning of tick-borne pathogen risk. However, we pose the question as to what extent the ecological approach used here for I. scapularis-borne zoonoses can be applied as a general model for public health purposes.