In acute non-complicated cases of traveler’s diarrhea, identification of the agent responsible for traveler’s diarrhea is usually not necessary. Diagnostic laboratory tests for traveler’s diarrhea usually include either stool culture, ELISA, or polymerase chain reaction (PCR). Other laboratory findings in traveler’s diarrhea are usually non-specific and may include increased white blood cell count and elevated inflammatory markers. Laboratory findings suggestive of dehydration may include relative polycythemia, metabolic alkalosis, elevated BUN and serum creatinine (suggestive of pre-renal acute kidney injury). When hospitalized, patients should also be monitored for laboratory findings that may suggest development of complications associated with traveler’s diarrhea.

• Stool cultures

• Usually considered a reliable diagnostic test with good sensitivity
• The choice of culture medium depends on clinical suspicion
• Stool ova and parasites (O & P) test may not be performed routinely for stool culture and may be requested separately

• Serotyping

• ELISA detects toxins in stools and antibodies in serum

• Polymerase chain reaction (PCR)

• Detection of infectious agents and expression of endotoxins

• Lab findings of traveler’s diarrhea are usually related to the extent of dehydration or development of complications. Lab findings include:

• WBC count may be normal or elevated
• Elevated concentration of inflammatory markers (e.g. CRP or ESR)
• Chloride-sensitive metabolic alkalosis and electrolyte derangement (commonly hypokalemia)
• Relative polycythemia in cases of dehydration or hemolytic anemia in cases of hemolytic uremic syndrome
• Elevated BUN
• Elevated serum creatinine