Persistent Diarrhea: A Clinical Review.

IMPORTANCE: Diarrheal disease is commonly encountered in clinical practice. Persistent diarrhea (≥14 days) can be caused by pathogens that differ from those commonly seen in acute illness; proper etiologic diagnosis is important for appropriate therapeutic management. This review provides an overview of the epidemiology, etiology, diagnosis, and management of persistent diarrhea caused by infectious agents in immunocompetent individuals worldwide. OBSERVATIONS: Much of the data on persistent diarrhea comes from studies of residents in or expatriates of developing countries and travelers to these regions where follow-up studies have been performed. Persistent diarrhea occurs in approximately 3% of individuals traveling to developing countries. Schistosoma mansoni (and rarely Schistosoma haematobium) intestinal infection is also not very common and is found only in endemic areas. The microbiologic causes of protracted diarrhea include detectable parasitic (eg, Giardia, Cryptosporidium) and bacterial (eg, enteroaggregative Escherichia coli, Shigella) pathogens. Available diagnostic tests include culture-dependent for bacterial pathogens and culture-independent methods for bacterial, viral, and protozoal infections (eg, polymerase chain reaction [PCR]), including multiplex PCR, as well as and microscopy for protozoal infections. Antimicrobial therapy can be given empirically to patients returning from the undeveloped to the developed world. Otherwise, antibiotics should be given based on the results of laboratory testing. CONCLUSIONS AND RELEVANCE: Persistent diarrhea is a poorly recognized syndrome in all populations that requires proper assessment and diagnosis to ensure that affected individuals receive the treatment needed to experience improvement of clinical symptoms.