Stephen was located at the Wellcome Africa- Asia programme in Vietnam for 11 years, where he established an internationally recognised programme of research on enteric (gastrointestinal) infections. This work has been closely linked to work at University of Cambridge and the Sanger Institute leading to >40 co-authored publications since 2013.
The work in Stephen’s lab focusses on understanding how specific bacteria that cause infectious disease in humans in low-middle income countries evolve and spread with a specific focus on typhoid fever, bacillary dysentery (Shigella), as well as other diarrheal diseases such as cholera and rotavirus. The areas of research he plans to explore within CITIID over the next 5 years will include; continuing work on the phylogeography of enteric bacteria, looking more closely at evolutionary adaptation and clonal replacement of gastrointestinal pathogens in endemic settings through cohort studies and hospital surveillance. More broadly the key areas of focus will be the impact of antimicrobial access and treatment on the gut microbiota and the generation of drug resistant pathogens. His work will maintain an international focus and will lead into developing new interventions for treating and preventing infections cause by antimicrobials resistant pathogens.
In March 2020, Stephen's lab repurposed in order to provide quick COVID-19 testing for health care workers at Addenbrooke's Hospital.