title: Prospective study of pathogens in asymptomatic travellers and those with diarrhoea: aetiological agents revisited.
abstract: Travellers' diarrhoea (TD) remains the most frequent health problem encountered by visitors to the (sub)tropics. Traditional stool culture identifies the pathogen in only 15% of cases. Exploiting PCR-based methods, we investigated TD pathogens with a focus on asymptomatic travellers and severity of symptoms. Pre- and post-travel stools of 382 travellers with no history of antibiotic use during travel were analysed with a multiplex quantitative PCR for Salmonella, Yersinia, Campylobacter, Shigella, Vibrio cholerae and five diarrhoeagenic Escherichia coli: enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC) and enteroinvasive (EIEC). The participants were categorized by presence/absence of TD during travel and on return, and by severity of symptoms. A pathogen was indentified in 61% of the asymptomatic travellers, 83% of those with resolved TD, and 83% of those with ongoing TD; 25%, 43% and 53% had multiple pathogens, respectively. EPEC, EAEC, ETEC and Campylobacter associated especially with ongoing TD symptoms. EAEC and EPEC proved more common than ETEC. To conclude, modern methodology challenges our perception of stool pathogens: all pathogens were common both in asymptomatic and symptomatic travellers. TD has a multibacterial nature, but diarrhoeal symptoms mostly associate with EAEC, EPEC, ETEC and Campylobacter.
authors.affiliation: Department of Medicine, University of Helsinki, Helsinki, Finland; Inflammation Centre, Clinic of Infectious Diseases, University of Helsinki and Helsinki University Hospital, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Lääveri
authors.affiliation: Department of Clinical Microbiology, Helsinki University Hospital, HUSLAB, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Antikainen
authors.affiliation: Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland.
authors.forename: S H
authors.initials: SH
authors.lastname: Pakkanen
authors.affiliation: Department of Clinical Microbiology, Helsinki University Hospital, HUSLAB, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Kirveskari
authors.affiliation: Department of Medicine, University of Helsinki, Helsinki, Finland; Inflammation Centre, Clinic of Infectious Diseases, University of Helsinki and Helsinki University Hospital, Finland; Aava Travel Clinic, Medical Centre Aava, Helsinki, Finland; Unit of Infectious Diseases, Department of Medicine/Solna, Karolinska Institutet, Stockholm, Sweden. Electronic address: anu.kantele@hus.fi.
authors.forename: A
authors.initials: A
authors.lastname: Kantele
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D012720:Severity of Illness Index; D014195:Travel; D055815:Young Adult
keywords: Aetiology; Campylobacter; diarrhoea; enteroaggregative Escherichia coli; enteropathogenic E. coli; enterotoxigenic Escherichia coli; quantitative RT-PCR; travel