What are the common etiologies of persistent diarrhea?

From the Guidelines

Persistent diarrhea, defined as diarrhea lasting more than 14 days, has several common etiologies, including infectious agents, inflammatory bowel diseases, malabsorption syndromes, medication side effects, and functional causes, as outlined in the 2017 Infectious Diseases Society of America clinical practice guidelines 1.

Common Etiologies of Persistent Diarrhea

The most frequent causes of persistent diarrhea include:

• Infectious agents such as parasites (Giardia lamblia, Cryptosporidium, Entamoeba histolytica), bacteria (Clostridioides difficile, especially after antibiotic use), and viruses (cytomegalovirus in immunocompromised patients) 1
• Inflammatory bowel diseases like Crohn's disease and ulcerative colitis 1
• Malabsorption syndromes including celiac disease, lactose intolerance, and pancreatic insufficiency 1
• Medication side effects, particularly from antibiotics, proton pump inhibitors, metformin, and certain antihypertensives 1
• Irritable bowel syndrome with diarrhea predominance (IBS-D) represents a functional cause 1
• Microscopic colitis, often seen in older adults, can cause watery diarrhea without visible inflammation on endoscopy 1
• Endocrine disorders such as hyperthyroidism and certain neuroendocrine tumors may also cause persistent diarrhea 1

Diagnostic Approach

A broad differential diagnosis is recommended in immunocompromised people with diarrhea, especially those with moderate and severe primary or secondary immune deficiencies, for evaluation of stool specimens by culture, viral studies, and examination for parasites 1.

Management

The management of persistent diarrhea depends on the underlying cause, and may involve antimicrobial therapy, supportive care, and treatment of underlying conditions 1.

From the Research

Common Etiologies of Persistent Diarrhea

The common etiologies of persistent diarrhea can be categorized into several groups, including:

• Infectious agents, such as:
  • Parasitic pathogens, including Giardia, Cryptosporidium, and Entamoeba histolytica 2, 3, 4
  • Bacterial pathogens, including enteroaggregative Escherichia coli, Shigella, and Yersinia 2, 4
• Non-infectious causes, such as:
  • Inflammatory bowel disease 5
  • Celiac disease 3, 5
  • Irritable bowel syndrome with diarrhea (IBS-D) 5
  • Small intestinal bacterial overgrowth, bile acid malabsorption, food intolerance, and motility disorders 5
• Other causes, such as:
  • Schistosoma mansoni intestinal infection, although this is rare and typically found in endemic areas 2
  • Hyperthyroidism 3

Diagnostic Approaches

Diagnostic approaches for persistent diarrhea may include:

• Culture-dependent tests for bacterial pathogens 2
• Culture-independent methods, such as polymerase chain reaction (PCR) and microscopy, for bacterial, viral, and protozoal infections 2, 6
• Antimicrobial therapy, which may be given empirically or based on laboratory test results 2, 6

Management and Treatment

Management and treatment of persistent diarrhea depend on the underlying cause and may involve:

• Antiparasitic agents for parasitic infections 3
• Antibiotics for bacterial infections, although routine use is not recommended for most adults with mild, watery diarrhea 6
• Treatment of underlying conditions, such as inflammatory bowel disease or celiac disease 5