Travel-related respiratory symptoms and infections in travellers (2000-22): a systematic review and meta-analysis

Surveillance of global, travel-related illness using a novel app: a multivariable, cross-sectional study

INTRODUCTION

Current traveller health surveillance is 'top-down'. Mobile-based surveillance could capture infection symptoms in real time. We aimed to evaluate the spectrum of illness in travellers using a mobile app-based system.

METHODS

This study (ClinicalTrials.gov NCT04672577) used an application called Infection Tracking in Travellers (ITIT) that records travel-related illness symptoms with associated geolocation and weather data. The free ITIT app is available in 14 languages. Participants were recruited globally from April 2022 to July 2023. Participants >18 years of age travelled internationally and provided electronic consent. Incentives included the provision of travel health information imported from the WHO website. Symptoms were recorded with daily pop-up questionnaires and symptom severity was assessed using a Likert scale. Two post-travel questionnaires were administered. Logistic mixed models examined factors relating to symptom presence, and a random forest model examined symptom impact.

RESULTS

609 participants were recruited until July 2023. Participants had an average age of 37 years (18-79), and an average travel duration of 26 days (2-281). Most participants were travelling for leisure/tourism (401; 66%), followed by 'visiting friends and relatives' (99; 16%) and business travel (80; 13%). All continents were visited by at least one traveller. Of 470 registered trips, symptoms were reported on 163 trips (35%). Gastrointestinal symptoms were reported on 87 trips (19%) and respiratory symptoms on 81 trips (17%). The most important factors in predicting the presence of symptoms were duration of travel, travelling in winter and high humidity. Diarrhoea, headache and nausea were symptoms with most impact on daily activities. Post-travel questionnaires showed that 12% of surveyed participants experienced symptoms with several episodes of self-treatment. Two diagnoses were recorded: Lyme disease and amoebic dysentery.

CONCLUSION

The digital tool ITIT successfully captures the spectrum of travel-related illness. This detailed epidemiology is crucial for outbreak detection and for the formulation of travel medicine guidelines.

TRIAL REGISTRATION NUMBER

NCT04672577.

Pulmonary infections in the returning traveler

PURPOSE OF REVIEW

The recent COVID-19 pandemic has shaped the epidemiology of other infectious diseases globally. International tourist arrivals are increasing and recovering to prepandemic levels. This review focuses on respiratory infections in travelers, highlighting the characteristics of the main imported viral, bacterial, fungal, and parasitic infections with pulmonary involvement.

RECENT FINDINGS

A recent systematic review estimated a prevalence of respiratory symptoms in travelers of around 35%, increasing to nearly 65% in the context of mass gatherings. Common viral and bacterial pathogens account for the majority of respiratory infections with an identified cause; however, recent data focus on the need for surveillance of emerging infections such as MERS-CoV, henipaviruses and multidrug resistant bacteria, which may be spread through travel. Fungal and parasitic respiratory infections are less common, and acquisition is usually associated with specific risk factors or exposure in endemic areas. Special risk groups, such as immunocompromised travelers, may be particularly vulnerable, presenting with severe disease or reactivation of latent infections.

SUMMARY

The next significant international epidemic could involve another new infectious agent causing respiratory disease and spreading via mobile populations. Official protocols should be adhered to, and public health interventions implemented for effective control. Continued and globally coordinated investments in research for new vaccines, therapeutic agents, disease modeling, and digital tracking strategies are essential.