The quantified self during travel: mapping health in a prospective cohort of travellers. 
Travel medicine research has remained relatively unchanged in the face of rapid expansion of international travel and is unlikely to meet health challenges beyond infectious diseases.  Our aim was to identify the range of health outcomes during travel using real-time monitoring and daily reporting of health behaviours and outcomes and identify traveller subgroups who may benefit from more targeted advice before and during travel.  We recruited a prospective cohort of travellers ≥ 18 years and planning travel to Thailand for <5 weeks from the travel clinics in Zurich and Basel (Switzerland).  Participants answered demographic, clinical and risk behaviour questionnaires pre-travel and a daily health questionnaire each day during travel using a smartphone application.  Environmental and location data were collected passively by GPS.  Classification trees were used to identify predictors of health behaviour and outcomes during travel.  Non-infectious disease events were relatively common, with 22.7% (17 out of 75 travellers) experiencing an accident, 40.0% ( n = 30) a wound or cut and 14.7% ( n = 11) a bite or lick from an animal.  Mental health associated events were widely reported, with 80.0% ( n = 60) reporting lethargy, 34.7% ( n = 26) anxiety and 34.7% ( n = 26) feeling tense or irritable.  Classification trees identified age, trip length, previous travel experience and having experienced a sports injury in the past year as the most important discriminatory variables for health threats.  Our study offers a revolutionary look at an almost real-time timeline of health events and behaviours during travel using mHealth technology.  Non-infectious disease related health issues were common in this cohort, despite being largely unaddressed in traditional travel medicine research and suggest a substantial potential for improving evidence-based travel medicine advice.