My research uses clinical epidemiological methods to address infectious and tropical diseases and other global health problems. I have experience conducting randomised controlled trials, observational studies, systematic reviews, qualitative research and cost-effectiveness studies, working particularly with collaborators in Southeast Asia.

Leptospirosis and clinical trials

Leptospirosis is a major focus of my research. Working with colleagues and postgraduate researchers at Nagasaki University, LSHTM and partner institutions, we have developed a programme spanning epidemiology, diagnosis, evidence synthesis and treatment.

We have published Cochrane reviews of antibiotic prophylaxis, antibiotic treatment, and corticosteroid treatment for leptospirosis, and contributed to epidemiological and clinical studies in the Philippines and other settings. PhD student Nathaniel Lee has led development of a Core Outcome Set for leptospirosis trials (COS-LEP), providing a foundation for future treatment trials. We reported leptospirosis as an important cause of fever and jaundice in the Democratic Republic of the Congo.

Our current work is moving from evidence synthesis and observational research towards interventional studies. Two recently awarded grants support this development. Funding from the Japan Society for the Promotion of Science (JSPS; KAKENHI) supports the run-in phase of a randomised controlled trial of adjunctive corticosteroids for moderate-to-severe leptospirosis in the Philippines and development of clinical trial capacity. A Wellcome Trust trial development award supports work towards a definitive multicentre trial.

This work builds on the long-standing San Lazaro Hospital-Nagasaki University collaboration in the Philippines and involves colleagues at LSHTM and other institutions in Japan, Southeast Asia and internationally. We also collaborate with wider Japanese infectious disease research initiatives, including AMED-supported ARISE and SCARDA programmes.

Infectious and tropical diseases

Since starting my joint LSHTM-Nagasaki University position in 2017, I have contributed to research across a range of infectious and tropical diseases, particularly through the San Lazaro Hospital–Nagasaki University collaborative research programme in the Philippines.

Our work on undifferentiated febrile illness and community-acquired bloodstream infections has supported studies of diseases including typhoid fever, diphtheria and dengue. Other collaborative research has included rabies, measles, snakebite and tuberculosis, frequently involving Master's and PhD students.

In Malaysia, I contribute to a SATREPS programme funded by AMED and JICA investigating zoonotic Plasmodium knowlesi malaria in Sabah. My work focuses particularly on evaluation of a community risk-education intervention, including a cluster-randomised trial.

Digital health and reproductive health

I became interested in family planning when I worked for the Maddox Jolie-Pitt Foundation and the UK National Health Service on a health project in rural Cambodia which involved establishing family planning services at the health centres. We learned that there was demand for family planning but at the same time contraceptive discontinuation was common, mainly due to fear or experience of side-effects. It was the concept that additional support could be provided by mobile phone that led me to the topic of my PhD research.

My PhD, which was funded by the UK Medical Research Council (2014-17) focussed on understanding the effectiveness of digital health interventions delivered by mobile phone to increase contraception use. I was the lead investigator of the Marie Stopes International funded MObile Technology for Improved Family Planning (MOTIF) trial of an intervention comprising automated voice messages +/- counsellor support for contraception in Cambodia. The intervention increased use of post-abortion contraception, was acceptable and cost-effective, and subsequently included as a case study of digital technology high-impact practice in family planning for social and behavior change.

Our 2015 Cochrane review of Mobile phone-based interventions to improve contraception use identified five randomised controlled trials. For our update of this review published in 2023 we identified 23 trials indicating significant activity in this area. We were able to conduct a meta-analysis demonstrating evidence to support mobile phone-based interventions in improving the use of contraception, compare unidirectional and interactive interactions, and code behaviour change techniques in the interventions.

I was the principal investigator of a project funded by the Arts & Humanities Research Council (AHRC) from 2018 to 2020 to develop interventions (edutainment videos) to support reproductive health of garment factory workers in Cambodia.
I have provided support to related projects at LSHTM (trials in Bangladesh and Zimbabwe) and Oxford University (investigating side effects in Ethiopia).

COVID-19 and emerging infections

During the COVID-19 pandemic, our collaborations included the report of the first COVID-19 cases in the Philippines, followed by studies of clinical characteristics, seroepidemiology and vaccine effectiveness.

I was UK Principal Investigator of a UKRI-funded collaboration with the Oswaldo Cruz Institute investigating SARS-CoV-2 infection and immunity among children and household contacts in Rio de Janeiro, Brazil. This prospective cohort generated studies of infection dynamics, SARS-CoV-2 incidence over four epidemic waves, and the role of children across successive waves of the pandemic.

I have also contributed to research on public responses to COVID-19 public health measures and led a Japan Society for the Promotion of Science-funded study of international travel and quarantine experiences during the pandemic.

Other activities
I undertake peer review for various journals and am an editor for Tropical Medicine and Health. Further details of publications, grants and research activities are also available through my ORCID and ResearchMap profiles.