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Acute diarrhea

Acute diarrhea is a clinical syndrome that is defined as the passage of ≥ 3 unformed stools per day for < 2 weeks.
Frequent causes include viruses (norovirus, rotavirus), bacteria (Campylobacter, C. difficile, Salmonella, E. coli, Shigella), parasites (Giardia, Cryptosporidium), side-effects of medications (antibiotics, colchicine), abdominal surgeries, gastroenterologic diseases (ulcerative colitis, Crohn's disease, diverticulitis, appendicitis), and endocrine diseases (hyperthyroidism, carcinoid tumors).
In the US, the incidence of acute diarrhea is approximately 60,000 cases per 100,000 person-years.
Disease course
Untreated, severe diarrhea may lead to dehydration, renal failure, and shock.
Prognosis and risk of recurrence
In developing countries, it is a common cause of death, especially in children.
Key sources
The following summarized guidelines for the evaluation and management of acute diarrhea are prepared by our editorial team based on guidelines from the American Academy of Family Physicians (AAFP 2023), the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN 2023), the Spanish Association of Pediatrics (AEP 2021), the Infectious Diseases Society of America (IDSA 2017), and the American College of Gastroenterology (ACG 2016).


1.Diagnostic investigations

Clinical history
Obtain a detailed clinical and exposure history in patients presenting with acute diarrhea.
Evaluate for postinfectious and extraintestinal manifestations of enteric infections in patients with acute diarrhea.
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  • Physical examination

  • CBC

  • Blood cultures

  • Indications for diagnostic testing

  • Stool specimen

  • Antibiotic sensitivity testing

  • Culture-independent stool testing

  • C. difficile testing

  • Ova and parasite examination

  • Fecal leukocytes

  • Fecal lactoferrin

  • Fecal calprotectin

  • Diagnostic imaging

2.Diagnostic procedures

Upper gastrointestinal endoscopy: consider obtaining a duodenal aspirate in patients in whom there is a suspected diagnosis of Giardia, Strongyloides, Cystoisospora, or microsporidia infection.

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  • Lower gastrointestinal endoscopy

3.Medical management

General principles: avoid empiric anti-microbial therapy for acute diarrheal infection, except in cases of travellers' diarrhea, where the likelihood of bacterial pathogens is high enough to justify the potential side effects of antibiotics.
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  • Oral rehydration

  • Intravenous fluids

  • Symptomatic therapy

  • Empiric antibiotic therapy (bloody diarrhea)

  • Empiric antibiotic therapy (watery diarrhea)

  • Choice of antibiotic agent

4.Inpatient care

Serial clinical and laboratory assessment: obtain the following assessments during rapid IV rehydration in pediatric patients:
Vital signs
HR and BP (at least in the initial assessment)
Physical examination
General health, level of dehydration (use validated scales), and symptoms and signs of volume overload
Fluid balance (input and output)
Determine the frequency with which these assessments should be obtained depending on the clinical condition and evolution of the patient
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5.Nonpharmacologic interventions

Oral zinc supplements: initiate oral zinc supplementation to reduce the duration of diarrhea in pediatric patients aged 6 months to 5 years residing in countries with a high prevalence of zinc deficiency or having signs of malnutrition.

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  • Probiotics

6.Specific circumstances

Immunocompromised patients
Develop a broad differential diagnosis in immunocompromised patients with diarrhea, especially those with moderate and severe primary or secondary immune deficiencies, and obtain evaluation of stool specimens by culture, viral studies, and examination for parasites.
Obtain additional testing for other organisms including, but not limited to, Cryptosporidium, Cyclospora, Cystoisospora, microsporidia, M. avium complex, and CMV, in patients with acquired immune deficiency syndrome and persistent diarrhea.

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  • Patients with asymptomatic infection

  • Patients with traveler's diarrhea

  • Patients with STEC infection

7.Patient education

General counseling
Direct educational efforts toward all patients with diarrhea, but particularly to patients with primary and secondary immune deficiencies, pregnant patients, parents of young children, and the elderly, as they have an increased risk of complications from diarrheal disease.
Counsel patients with diarrhea to avoid swimming, water-related activities, and sexual contact with others when symptomatic while adhering to meticulous hand hygiene.

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  • Food safety practices

  • Pretravel counseling

8.Preventative measures

Hand hygiene: as per IDSA 2017 guidelines, counsel patients to perform hand hygiene after using the bathroom, changing diapers, before and after preparing food, before eating, after handling garbage or soiled laundry items, and after touching animals or their feces or environments, especially in public settings such as petting zoos.
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  • Rotavirus immunization

  • Typhoid immunization

  • Cholera immunization

  • Antibiotic prophylaxis

  • Bismuth subsalicylate

9.Follow-up and surveillance

Follow-up testing: avoid obtaining follow-up testing in most patients following resolution of diarrhea.
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  • Management of nonresponse to treatment

10.Quality improvement

Public health reporting: report all diseases listed in the table of National Notifiable Diseases Surveillance System at the national level, including those that cause diarrhea, to the appropriate state, territorial, or local health department with submission of isolates of certain pathogens such asSalmonella , STEC,Shigella , and Listeria, to ensure implementation of control and prevention practices.
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