Persistent Diarrhea Definition
Persistent diarrhea is defined as diarrhea lasting 14 days or more. According to the Infectious Diseases Society of America (IDSA) clinical practice guidelines, diarrhea is categorized based on duration, with persistent diarrhea specifically defined as diarrhea that lasts 14 through 29 days 1.
Classification of Diarrhea by Duration
The clinical classification of diarrhea based on duration is as follows:
- Acute diarrhea: Less than 14 days
- Persistent diarrhea: 14-29 days
- Chronic diarrhea: 30 days or longer
This classification system is well-established in the medical literature and supported by multiple clinical practice guidelines 1.
Clinical Significance of Persistent Diarrhea
Persistent diarrhea represents an important clinical entity that requires specific attention because:
- It has different etiological considerations than acute diarrhea
- It carries higher morbidity and mortality risks, particularly in vulnerable populations
- It may indicate underlying pathology requiring specific diagnostic workup
The 2017 IDSA guidelines specifically note that persistent diarrhea occurs in approximately 8% of diarrheal episodes in US children, with an incidence of about 0.18 episodes per person-year 2. While less common than acute diarrhea, persistent diarrhea is more likely to result in medical visits (28% vs 8.2% for acute episodes) 2.
Management Implications
The distinction between acute and persistent diarrhea has important management implications:
- Empiric antimicrobial therapy: Should be avoided in people with persistent watery diarrhea lasting 14 days or more 1
- Diagnostic testing: More extensive evaluation is warranted for persistent diarrhea compared to acute diarrhea
- Nutritional support: Becomes increasingly important as diarrhea persists beyond 14 days
Etiological Considerations
The etiology of persistent diarrhea differs from acute diarrhea:
- Viral pathogens (norovirus, rotavirus, sapovirus) are significantly more prevalent in persistent diarrhea compared to baseline 2
- Certain bacterial pathogens (EPEC, Salmonella, EAEC) and parasites (Cryptosporidium) are important considerations 3
- Approximately 59% of persistent diarrhea cases in US children have no identifiable pathogen with current testing methods 2
Answer to Multiple Choice Question
Based on the evidence presented, the correct answer is A. 14 days but less than a month. This aligns with the definition provided in the IDSA guidelines that persistent diarrhea lasts 14 through 29 days 1.