Causes
| E. coli, enterotoxigenic | 20-75% |
| E. coli, enteroaggregative | 0-20% |
| E. coli, enteroinvasive | 0-6% |
| Shigella spp | 2-30% |
| Salmonella spp | 0-33% |
| Campylobacter jejuni | 3-17% |
| Vibrio parahemolyticus | 0-31% |
| Aeromonas hydrophila | 0-30% |
| Giardia lamblia | 0 to less than 20% |
| Entamoeba histolytica | 0-5% |
| Cryptosporidium sp | 0 to less than 20% |
| Rotavirus | 0-36% |
| Norwalk virus | 0-10% |
Infectious agents are the primary cause of travelers' diarrhea. Bacterial enteropathogens cause approximately 80% of cases. Viruses and protozoans account for most of the rest.
The most common causative agent isolated in countries surveyed has been enterotoxigenic Escherichia coli (ETEC). Enteroaggregative E. coli is increasingly recognized and many studies do not look for this important bacterium. Shigella spp. and Salmonella spp. are other common bacterial pathogens. Campylobacter, Yersinia, Aeromonas, and Plesiomonas spp. are less frequently found. Some bacteria release toxins which bind to the intestinal wall and cause diarrhea; others damage the intestines themselves by their direct presence.
While viruses are associated with less than 20% of adult cases of traveler's diarrhea, they may be responsible for nearly 70% of cases in infants and children. Diarrhea due to viral agents is unaffected by antibiotic therapy, but is usually self-limited. Protozoans such as Giardia lamblia and Cryptosporidium can also cause diarrhea.
Pathogens implicated in travelers' diarrhea appear in the table at right.
A sub-type of traveler's diarrhea afflicting hikers and campers, sometimes known as wilderness diarrhea, may have a somewhat different frequency distribution of pathogens.
Read more about this topic: Traveler's Diarrhea