**3.2 Transmission and reservoirs**

Typical EPEC transmission follows a fecal-oral process through contaminated surfaces, weaning fluids, and human carriers [32]. EPEC outbreaks among adults, although rare, seem to occur through ingestion of contaminated food and water; however, no specific environmental reservoir has been identified [24]. EPEC outbreaks have been reported to show a seasonal distribution with peaks during the warm months [33]. Humans are the only known reservoir for typical EPEC, with symptomatic and asymptomatic children and asymptomatic adults being the most likely source [24].

In contrast to the tEPEC, many aEPEC strains have been found in diarrheic as well as in healthy animals and from the environment. Interestingly, animal aEPEC serogroups associated with human diarrhea have been identified (e.g., O26, O103, O119, O128, O142, and O157); however, so far a direct transmission from animals to humans has not been confirmed. In addition, foods including raw meats, pasteurized milk, meat samples, vegetables, and water have been also implicated as vehicles of aEPEC to human infections (reviewed in [34, 35]).
