PhD is an Alumni Professor in the Biological Sciences, professor of entomology and director of Penn State's Center for Infectious Disease Dynamics. He studies the evolution of pathogens, driven by modern medicine and farming.
His research focuses on the ecology and evolutionary genetics of infectious disease, including:
Evolution and virulence
Interactions between pathogens
- How do public and animal health programs affect pathogen evolution (particularly the evolution of virulence)? Having developed a theoretical framework, we are now testing its predictions in laboratory experimental systems.
- To what extent are parasite virulence and host resistance environmentally determined?
- How does natural selection resolve the trade-off pathogens face between replication within a host and transmission from it?
- How does host resistance affect pathogen evolution?
- Why is malaria not a more serious disease?
Phylodynamics and the evolution of immunity
- When and how do malaria clones coinfecting a host compete? What determines the outcome of competition? How does competition affect clone fitness? How does competition affect the evolution of virulence and other traits?
- Is within-host competition seen in mixed Trypanosome clone infections?
- How does host immunity shape parasite life history strategies?
- Do genetically diverse infections make hosts sicker or more infectious?
- When and how does pathogen-imposed selection favour increased host resistance?
- How do immune systems evolve?
- Will vaccination and chemotherapy prompt the evolution of more virulent pathogens?
- Can entomopathogenic fungi be used to produce a cheap organic pesticide for sustainable malaria control?
- Can we make evolution-proof drugs, vaccines and insecticides?
- Much disease is immunopathology. Why does natural selection allow self-harm?