App enables faster tracking of travel-related illnesses

Gastrointestinal complaints were the most common health issue reported by people going abroad who took part in a survey on travel-related illnesses.

The study was based on data from a mobile application developed by researchers at the University of Zurich (UZH) with the World Health Organization (WHO). 

“Travelers are an excellent reflection of what’s happening around the globe. They also often play a part in introducing pathogens to different regions of the world. This real-time bottom-up approach is much faster than top-down reporting systems. Mobile technologies offer a revolutionary solution to how we track travel-related illnesses,” said study leader Patricia Schlagenhauf from the Epidemiology, Biostatistics, and Prevention Institute at UZH.

Scientists said early outbreak detection and reporting of travel-related illnesses was crucial to implementing effective public health measures. Top-down systems rely on healthcare professionals, laboratories, and official health agencies to report mandatory infections.  

Bottom-up reporting by travelers ensures timely detection of illness clusters, allowing prompt investigation and intervention and can provide insights into environmental exposures, regional risk factors, and potential disease hotspots.

Tracking travel-related infections
The Illness Tracking in Travellers (ITIT) app allows people to report daily symptoms by type, intensity and impact through filling in a short questionnaire. This information is then linked to location data as well as climate and air quality information.

The research team analyzed data collected through the app between April 2022 and July 2023. The analysis covered 470 trips recorded by 609 people across all continents. Findings were published in the journal BMJ Open.

Participants had an average age of 37 but ranged from 18 to 79 years old, and an average travel duration of 26 days with a range of 2 to 281 days. Most people were traveling for leisure or tourism, followed by visiting friends and relatives, and business travel.

Overall, 404 travelers who downloaded the app and completed the demographic survey also filled out at least one daily survey. Of 470 registered trips, people reported having symptoms on at least one day during their travels on 163 trips. Gastrointestinal issues were reported on 87 trips.

The most common health issues were gastrointestinal symptoms, which were reported in 19 percent of trips and most frequently in travelers to Asia, where the risk of foodborne pathogens can be high. These symptoms occurred less often in people going to Africa. Significantly more women than men reported symptoms of diarrhea. It is possible that women are more susceptible to diarrhea, or that they were more conscientious when recording information in the app.

Duration of travel, higher humidity, and atmospheric ammonia were associated with gastrointestinal symptom presence. Diarrhea, headache, and nausea symptoms with the top impact on daily activities.

One possible bias may be that people who were more health conscious and willing to take part in citizen science were included in the dataset.

The free ITIT app is available in 14 languages. Researchers are inviting more people to use the app. Larger sets of data would enable them to run automated analyses using artificial intelligence. The updated app will also monitor persisting illness post-travel.

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