Abstract
We review the most recent work conducted by our group on the circulation of infectious agents in mobile populations, including pilgrims participating in the Hajj (Mecca, Saudi Arabia) and the Grand Magal of Touba (Senegal) pilgrimages, homeless people, and medical students participating in an elective abroad. Using a similar epidemiological study design with standardized questionnaires and molecular assays allows comparison of different populations of travelers. The main infectious pathogens and antibiotic resistance genes linked to travel were identified in certain specific populations of travelers, as well as in a group of homeless migrant people in Marseille. The role of several risk factors has also been demonstrated, allowing identifying individuals at increased risk of disease or pathogen carriage on which to base targeted preventive measures. Such results, together with those obtained through international surveillance networks allow better description of the epidemiology of travel-associated infectious diseases.
Highlights
Successive waves of migrants have settled in Marseille, originating mostly from Algeria, Armenia, Corsica, Lebanon, Morocco, Tunisia, Portugal, the Comoros and Italy, making the city population one of the most cosmopolitan in France with around 1.5 million inhabitants
Results from large multicentric surveys conducted by GeoSentinel and EuroTravNet on ill international travelers have clearly underlined the critical role of the traveler’s profile in the clinical pattern of travel-associated diseases [39,40] the major limitation of these network studies is the lack of a denominator, precluding calculation of the proportion of ill travelers among all travelers [41]
In the prospective cohort surveys that we conducted on international travelers (Hajj pilgrims or medical students) and on domestic travelers (Grand Magal pilgrims), each traveler is their own control when assessing their health status or pathogen carriage before and after exposure to a potential risk factor. One-day cross-sectional surveys conducted in homeless people evaluate the prevalence of disease and pathogen carriage in the population investigated
Summary
Successive waves of migrants have settled in Marseille, originating mostly from Algeria, Armenia, Corsica, Lebanon, Morocco, Tunisia, Portugal, the Comoros and Italy, making the city population one of the most cosmopolitan in France with around 1.5 million inhabitants. We summarize our most recent work on the molecular epidemiology of microbes and antibiotic resistance genes in special populations of travelers, including pilgrims participating in MGs, homeless people and medical students abroad. Pre- and post-travel kits, which contained questionnaires, sampling equipment (rigid cotton-tipped swab applicators and Figure 1 | Countries of origin of sheltered homeless people in Marseille (yellow), countries of destination of medical students participating in an elective abroad (red), countries where a pilgrimage takes place: Hajj (purple) and Grand Magal de Touba (green). Molecular prevalence surveys of the Antibiotic-resistance encoding Genes (ARGs) were performed on respiratory or rectal samples and compared to that of a control group (defined as the non-homeless group), including administrative staff, physicians, nurses, medical students and PhD students from our institute [19].
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