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 parahaemolyticus 0–31% Aeromonas hydrophila 0–30% Giardia lamblia 0–20% Entamoeba histolytica 0–5% Cryptosporidium spp. 0–20% Cyclospora cayetanensis ? Rotavirus 0–36% Norovirus 0–10% Infectious agents are the primary cause of<unk> . Bacterial enteropathogens cause about 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. Shigella spp. and Salmonella spp. are other common bacterial pathogens. Campylobacter, Yersinia, Aeromonas, and Plesiomonas spp. are less frequently found. Mechanisms of action vary: some bacteria release toxins which bind to the intestinal wall and cause<unk> ; others damage the intestines themselves by their direct presence. Brachyspira pilosicoli pathogen also appears to be responsible for many chronic intermittent watery<unk>  and is only diagnosed through colonic biopsies and microscopic discovery of a false brush border on H&E or Warthin silver stain: its brush-border is stronger and longer that Brachyspira aalborgi's brush-border. It is unfortunately often not diagnosed as coproculture does not allow growth and 16S PCR panel primers do not match Brachyspira sequences. While viruses are associated with less than 20% of adult cases of<unk> , they may be responsible for nearly 70% of cases in infants and children.<unk>  due to viral agents is unaffected by antibiotic therapy, but is usually self-limited. Protozoans such as Giardia lamblia, Cryptosporidium and Cyclospora cayetanensis can also cause<unk> . Pathogens commonly implicated in<unk>  appear in the table in this section. A subtype of<unk>  afflicting hikers and campers, sometimes known as wilderness<unk> , may have a somewhat different frequency of distribution of pathogens. Risk factors The primary source of infection is ingestion of fecally contaminated food or water. Attack rates are similar for men and women. The most important determinant of risk is the<unk> s destination. High-risk destinations include developing countries in Latin America, Africa, the Middle East, and Asia. Among backpackers, additional risk factors include drinking untreated surface water and failure to maintain personal hygiene practices and clean cookware. Campsites often have very primitive (if any) sanitation facilities, making them potentially as dangerous as any developing country. Although<unk>  usually resolves within three to five days (mean duration: 3.6 days), in about 20% of cases, the illness is severe enough to require bedrest, and in 10%, the illness duration exceeds one week. For those prone to serious infections, such as bacillary dysentery, amoebic dysentery, and cholera, TD can occasionally be life-threatening. Others at higher-than-average risk include young adults, immunosuppressed persons, persons with inflammatory bowel disease or diabetes, and those taking H2 blockers or antacids. Immunity<unk>  often get<unk>  from eating and drinking foods and beverages that have no adverse effects on local residents. This is due to immunity that develops with constant, repeated exposure to pathogenic organisms. The extent and duration of exposure necessary to acquire immunity has not been determined; it may vary with each individual organism. A study among expatriates in Nepal suggests that immunity may take up to seven years to develop—presumably in adults who avoid deliberate pathogen exposure. Conversely, immunity acquired by American students while living in Mexico disappeared, in one study, as quickly as eight weeks after cessation of exposure.
Travelers' diarrhea
Dysentery
Porcine epidemic diarrhoea
Bacillary dysentery
Cholera
Jamaican vomiting sickness
Riga–Fede disease
Rotaviral gastroenteritis