A long-term follow-up on persistence of diarrhoeal pathogens and symptoms among Finnish travellers visiting Benin, West Africa

Abstract

Travellers’ diarrhoea is the most common health problem among visitors to tropical and subtropical areas, West Africa as one of the destinations with the highest risk. Still, the data concerning the prevalence of diarrhoeal pathogens in Africa is limited. Occasionally colonization by diarrhoeal pathogens may last long after return, yet studies focusing on the duration of colonization after the travel and its related symptoms are practically lacking. The aims of this master’s thesis are to analyse the pathogenic bacteria findings of travellers returning from Benin, West Africa and to follow the persistence of the colonization and the diarrhoeal symptoms after return to Finland. Data was gathered from the volunteers (n = 290) that participated in OEV123, a Phase IIb study in an oral ETEC vaccine, ETVAX. The data included stool samples (n = 1099) from the follow-up period of three months and questionnaires filled by the participants. The detection of pathogens from the stool samples was carried out after DNA extraction by real-time quantitative PCR. The analyses of microbial findings and persistence of colonization were performed using SPSS and the analyses of questionnaires were performed using Excel. Among the target pathogens, EAEC, EPEC and ETEC were the most common findings. There were no cases of Yersinia. The rate of multiple bacteria findings was high on the first timepoint (44 %). The rate of each of the seven bacterial pathogens investigated decreased with time. On the last timepoint of follow-up period the three most important pathogens, EAEC, EPEC and ETEC decreased to a level as low as 15 % of the initial rate. The pathogenic bacteria were found from the stool samples associated with ongoing diarrhoea, as well as with those associated with no symptoms.