Table 2.
Common gastrointestinal pathogens
| Agent | Typical transmission | Likely symptoms | Diagnosis (stool studies) | Duration of symptoms | Outpatient treatment |
|---|---|---|---|---|---|
| Eschericia coli ETEC (traveler's diarrhea) | Contaminated food or water | Acute watery large-volume diarrhea | Stool culture | Self limited (1–4 days) | Empiric ATBX treatment shortens course |
| Eschericia coli EIEC | Contaminated food | Fever, abdominal pain, low-volume diarrhea | Stool culture | Varied | Definite ATBXs based on resistance patterns |
| Eschericia coli EHEC | Undercooked ground beef, human contact | Diarrhea, HUS | Stool culture | Symptoms begin after 1–8 days of incubation | Supportive, ATBXs thought to worsen disease course. |
| Salmonella typhi | Human contact, prepared food, contaminated water | Fever, abdominal pain, diarrhea | Blood culture, stool culture | 1–2 weeks incubation | Definite ATBXs based on resistance patterns |
| Salmonella (nontyphoidal) | Poultry, eggs, meat, dairy | Diarrhea (watery or bloody), fever | Stool culture | 1–4 days | Treat only with ATBXs in immunocompromised and asplenia |
| Shigella | Human contact, prepared food, contaminated water | Diarrhea (watery or bloody), fever | Stool culture | Varied; Some self-resolve in 7 days, others last weeks | Definite ATBXs based on resistance patterns |
| Campylobacter | Poultry, meat, dairy products, tap water | Diarrhea (watery or bloody), fever | Stool culture | 1–7 days | Supportive only |
| Calicivirus | Human contact (feces, vomitus), contaminated food and water | Fever, vomiting, diarrhea | PCR | 1–2 days | Supportive only |
| Rotavirus | Human contact, contaminated food and water | Fever, vomiting, diarrhea | EIA, latex agglutination | Diarrhea 3–8 days; Vomiting 1–5 days | Supportive only |
| Astrovirus | Human contact | Diarrhea, vomiting | EIA (not commercially available) | 1–14 days | Supportive only |
| Adenovirus types 40 and 41 | Human contact (feces, possibly vomitus) | Fever, vomiting, diarrhea | EIA (not commercially available) | 1–7 days | Supportive only |
| Giardia | Tap water, mountain streams, human contact | Abdominal discomfort, bloating, diarrhea, malaise, low-grade fever | Microscopic examination of feces; EIA | 3–4 days acute diarrhea then transition to subacute symptoms | Metronidazole |
| Cryptosproidium | Tap water, human contact | Large-volume diarrhea, abdominal pain, headache, fever | Microscopic examination of feces | 5–6 days typically; (range2–26 days) | In immunocompromised cases, consider antiparacystic/antibiotic treatment |
| Entamoeba histolytica | Human contact (feces), contaminated food or water | Fever, bloody diarrhea | Microscopic examination of feces | Mild symptoms may be present weeks to months | Use both luminal amebicide (for cysts) and tissue amebicide (for trophozoites) |
Abbreviations: ATBX, antibiotics; EHEC, enterohemorrhagic; EIA, enzyme immunoassay; EIEC, enteroinvasive; ETEC, enterotoxigenic; HUS, hemolytic uremic syndrome.
Data from Adachi AA, Backer HD, DuPont HL. Infectious diarrhea from wilderness and foreign travel. In: Auerbach PS, editor. Wilderness medicine. 4th edition. St. Louis (MO): Mosby; 2001. p. 1237–70; and Musher DM, Musher BL. Contagious acute gastrointestinal infections. N Engl J Med 2004;351(23):2417–27.