Prevalence of Diarrheagenic Escherichia coli in Finns with or without Diarrhea during a Round-the-World Trip

The incidence of diarrhea and the prevalence of bacterial enteropathogens, viruses, and parasites in feces of subjects with and without diarrhea were evaluated in 204 Finns traveling round the world (from Finland to China, Malaysia, Australia, Fiji, Chile, and Brazil and back to Finland). Special emphasis was placed on the finding of diarrheagenic Escherichia coli (enterotoxigenic, enteropathogenic, Shiga toxin-producing, and enteroaggregative strains) by PCR from growth on primary culture plates. From the PCR-positive samples, corresponding strains were isolated, confirmed as E. coli, and O serotyped. Of all the subjects, 37% experienced a total of 90 episodes of diarrhea. No adenoviruses or rotaviruses were detected, and findings of parasites were insignificant. In contrast, enteropathogenic bacteria were present in 62% of the 65 diarrheal and in 33% of the 127 nondiarrheal samples (P < 0.001); diarrheagenic E. coli strains were found in 35 and 26% of these, respectively (not statistically significant). As a single pathogen, E. coli was found in 20 and 24% of samples (not significant). Of all diarrheagenic E. coli strains, enteropathogenic strains were the most commonly found independently of the clinical picture of the subjects, whereas Salmonella enterica as a single pathogen was the most common non-E. coli organism found in diarrheal samples. Multiple bacterial pathogens were found 10 times more commonly in diarrheal than in nondiarrheal samples (20 versus 2%; P < 0.001).