Diarrhea

  • Diagnosis
  • Algorithms
  • Background
  • Lab Tests
  • References
  • Related Content

Indications for Testing

  • Persistent or chronic diarrhea
  • Bloody diarrhea
  • Diarrhea in association with systemic illness
  • Immunocompromised status
  • Returned traveler
  • Hospitalized patient
  • Outbreak identification

Laboratory Testing

Differential Diagnosis

Diarrhea in Healthy Pediatric Patients Testing Algorithm

Diarrhea in Hospitalized Adult Patients Testing Algorithm

Diarrhea in Immunocompromised Hosts Testing Algorithm

Diarrhea in Primary Care Adults Testing Algorithm

Diarrhea in Returned Traveller or Immigrant Testing Algorithm

Diarrhea may be infectious or noninfectious and presents with acute (<14 days) or persistent (>14 days) symptoms. Community-acquired disease is most common. Viruses (norovirus predominates) are the most common cause of acute infectious diarrhea in community dwellers. Bacterial diarrhea represents only ~1-5% of diarrhea cases, and is often associated with clustering of cases or outbreaks. Clostridium difficile cases, while often nosocomially-acquired, are increasing in community dwellers. Parasites are an infrequent or rare cause of acute diarrhea and tend to be sporadic in nature except in at-risk populations (eg, returned travelers, immunocompromised individuals).

Epidemiology

Risk Factors

  • Immunocompromised status
    • HIV,  primary immunodeficiency
      • Most common organisms include viruses, C. difficile, Campylobacter jejuniSalmonella spp, E. coli, Giardia, Cryptosporidium spp, and microsporidia
    • Transplantation (solid organ and stem cell)
      • Most diarrhea is not infectious
      • When infectious, most common organisms include viruses (norovirus most common), C. difficile, and microsporidia
  • Advanced age (>65 years)
    • Salmonella spp and Shigella spp may require treatment so identification is important
  • Comorbid illnesses (eg, chronic heartliver, or kidney disease; diabetes mellitus)
    • Increased risk of complications (eg, sepsis)
  • Institutional residency
    • Norovirus
  • Daycare setting
    • Norovirus
    • Giardia
    • Cryptosporidium spp
    • Salmonella spp

Clinical Presentation

  • Community-acquired
    • Acute diarrhea (acute gastroenteritis)
      • Duration – 1-14 days
      • Transmission – foodborne, waterborne, or outbreak-associated
      • Most commonly caused by viruses and occasionally bacteria
    • Persistent diarrhea
      • Duration – >14 days, often longer
      • Often noninfectious
      • Testing for parasites may be considered
      • Persistent diarrhea may be malabsorptive following an infectious diarrhea
  • Hospital-acquired
    • Presentation may be similar community-acquired disease
    • Most commonly caused by viruses
    • Prominent bacterial agent to rule out if correct history – C. difficile

Organisms associated with diarrhea (CDC, 2014)

Indications for Laboratory Testing

Tests generally appear in the order most useful for common clinical situations.
Click on number for test-specific information in the ARUP Laboratory Test Directory

Norovirus Group 1 and 2 Detection by RT-PCR 0051281
Method: Qualitative Reverse Transcription Polymerase Chain Reaction

Limitations

Negative result does not rule out the presence of PCR inhibitors (heme) in the patient specimen or norovirus nucleic acid concentrations below the level of detection of the assay

Does not rule out presence of bacterial or other viral causes of gastroenteritis

Rotavirus Antigen by EIA 0065088
Method: Qualitative Enzyme Immunoassay

Limitations

Does not rule out presence of bacterial or other viral causes of gastroenteritis

Negative result does not exclude the possibility of rotavirus infection

Low virus quantity or improper/inadequate sampling can cause false-negative results 

Rotavirus and Adenovirus 40-41 Antigens 0065067
Method: Qualitative Enzyme Immunoassay

Limitations

Does not rule out presence of bacterial or other viral causes of gastroenteritis

Negative result does not exclude the possibility of rotavirus infection

Low virus quantity or improper/inadequate sampling can cause false-negative results

Positive adenovirus results should be interpreted with caution since adenovirus is capable of latency and recrudescence

Asymptomatic shedding may persist for months after infection

False-positive adenovirus results can occur with high levels of Staphylococcus aureus expressing Protein A; however, staphylococcal enterocolitis is uncommon in adults and extremely rare in infants and children

Adenovirus 40-41 Antigens by EIA 0065066
Method: Qualitative Enzyme Immunoassay

Stool Culture and E. coli Shiga-like Toxin by EIA 0060134
Method: Culture/Identification

Limitations

Turnaround time 24->96 hours

Sensitivity highly variable

Clostridium difficile toxin B gene (tcdB) by PCR 2002838
Method: Qualitative Polymerase Chain Reaction

Gastrointestinal Bacterial Panel by PCR 2012678
Method: Qualitative Polymerase Chain Reaction

Limitations

A negative result does not rule out the presence of PCR inhibitors in the patient specimen or test-specific nucleic acid in concentrations below the level of detection by this test

Molecular assays will not detect rare or unusual enteric bacterial pathogens that are not specifically targeted by the test (eg, Aeromonas, Pleisiomonas, Yersinia, Vibrio, and enterotoxigenic E. coli)

A bacterial isolate is not obtained if antimicrobial susceptibility testing is indicated

Gastrointestinal Parasite and Microsporidia by PCR 2011660
Method: Qualitative Polymerase Chain Reaction

Limitations

Due to the periodic shedding of some parasites, a result of “not detected” cannot completely rule out infection with these parasites

If clinical signs and symptoms persist, an additional specimen for testing may be indicated

Viral and bacterial gastroenteritis are more common than parasitic gastroenteritis and should be considered as alternative diagnoses

Asymptomatic infections are known to occur, and therefore correlation of test results with clinical signs and symptoms is imperative

Does not detect helminths (flatworms, roundworms, and flukes), nonpathogenic protozoa, or Cystoisospora

Gastrointestinal Parasite Panel by PCR 2011150
Method: Qualitative Polymerase Chain Reaction

Limitations

Due to the periodic shedding of some parasites, a result of “not detected” cannot completely rule out infection with these parasites

If clinical signs and symptoms persist, an additional specimen for testing may be indicated

Viral and bacterial gastroenteritis are more common than parasitic gastroenteritis and should be considered as alternative diagnoses

Asymptomatic infections are known to occur, and therefore correlation of test results with clinical signs and symptoms is imperative

Does not detect helminths (flatworms, roundworms, and flukes), nonpathogenic protozoa, Cystoisospora, or microsporidia

Giardia Antigen by EIA 0060048
Method: Qualitative Enzyme Immunoassay

Limitations

Will not detect parasites other than G. duodenalis

Testing of second specimen may be indicated if first specimen is negative and clinical suspicion is high

Cryptosporidium Antigen by EIA 0060045
Method: Qualitative Enzyme Immunoassay

Limitations

Will not detect parasites other than Cryptosporidium spp

Parasitology Stain by Modified Acid-Fast 0060046
Method: Qualitative Concentration/Stain

Limitations

Not intended for detection of other stool parasites

Less sensitive than EIA for Cryptosporidium spp

Microsporidia by PCR 2011626
Method: Qualitative Polymerase Chain Reaction

Limitations

Presence of nucleic acid does not indicate presence of viable organisms; results should be used in conjunction with appropriate clinical symptoms for diagnostic purposes

Negative result does not rule out presence of PCR inhibitors in specimen or assay-specific nucleic acid in concentrations below the level of detection

Does not detect all possible pathogenic microsporidia spp

Limitations of PCR test should be considered during final diagnosis

If test yields a negative result and suspicion of microsporidia infection is high, a modified trichrome stain should be considered

Microsporidia Stain by Modified Trichrome 0060050
Method: Qualitative Stain

Limitations

Presence of nucleic acid does not indicate presence of viable organisms; results should be used in conjunction with appropriate clinical symptoms for diagnostic purposes

Does not detect all possible pathogenic microsporidia spp

Entamoeba histolytica Antigen, EIA 0058001
Method: Qualitative Enzyme Immunoassay

Limitations

Rarely positive in extraintestinal disease

Will not detect parasites other than E. histolytica

Ova and Parasite Exam, Fecal (Immunocompromised or Travel History) 2002272
Method: Qualitative Concentration/Trichrome Stain/Microscopy

Limitations

Ova may not be detectable in early disease

Does not specifically detect Cryptosporidium, CyclosporaCystoisospora, or microsporidia

Follow Up

In patients with negative O & P and persistent diarrhea, follow up negative stool antigen EIA result for Giardia duodenalis (synonym Giardia intestinalis, Giardia lamblia), Cryptosporidium spp, or Entamoeba histolytica

For Cryptosporidium, refer to the Cryptosporidium antigen by EIA test; for Cyclospora and Cystoisospora, refer to parasitology stain by modified acid-fast; for microsporidia, refer to microsporidia stain

Additional Tests Available

Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification

CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Comments

Nonspecific

May help in differentiation of bacterial from nonbacterial infection

Presence of anemia (low hemoglobin/hematocrit) suggestive of inflammatory or malignant process and not bacterial diarrhea

Campylobacter Antigen 0058002
Method: Qualitative Immunochromatography

Comments

Can be used in place of Campylobacter culture

Only specific for C. jejuni/C. coli

Entamoeba histolytica (amebiasis), Antibody, IgG 0050070
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Comments

Confirm past infection

Preferred test for extraintestinal disease (eg, liver abscess)

E. coli Shiga-like Toxin by EIA 0060047
Method: Qualitative Enzyme Immunoassay

Comments

Identifies presence of E. coli Shiga-like toxin

Does not determine specific serotypes of E. coli

Sensitivity is lower than PCR

Giardia lamblia Antibodies Panel by ELISA 2009410
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Comments

May be used to detect Giardia

Insensitive relative to stool EIA

Includes IgG, IgA, and IgM

Salmonella typhi and paratyphi Antibodies 2010798
Method: Qualitative Immunoblot

Comments

May be used to determine past exposure to S. typhi and S. paratyphi

Detects antibodies directed against 5 Salmonella typhi and paratyphi antigens: O Type D; O Type Vi; H Type A; H Type B; or H Type D

Stool Culture, Campylobacter 0060135
Method: Culture/Identification

Comments

Diagnose Campylobacter-associated diarrhea in patients with appropriate exposure history or risk factors

Culture is optimized only for C. jejuni/C. coli

Stool Culture, Yersinia 0060137
Method: Culture/Identification

Comments

Diagnose Yersinia-associated diarrhea in patients with appropriate exposure history or risk factors

Stool Culture, Vibrio 0060136
Method: Culture/Identification

Comments

Diagnose Vibrio-associated diarrhea in patients with appropriate exposure history or risk factors

Strongyloides Antibody, IgG by ELISA, Serum 0099564
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Comments

Confirm clinical suspicion of Strongyloides infection

Most sensitive test in chronic infections

Antibody cross-reactions in patients with filariasis may occur

Yersinia enterocolitica Antibodies, IgA, IgG, and IgM by Immunoblot 0051241
Method: Qualitative Immunoblot

Yersinia enterocolitica Antibody, IgG by Immunoblot 0051229
Method: Qualitative Immunoblot

Yersinia enterocolitica Antibody, IgM by Immunoblot 0051172
Method: Qualitative Immunoblot

Yersinia enterocolitica Antibody, IgA by Immunoblot 0051228
Method: Qualitative Immunoblot

Yersinia enterocolitica Antibodies, IgA and IgG by Immunoblot 0051230
Method: Qualitative Immunoblot

Guidelines

Foodborne Diseases Active Surveillance Network (FoodNet). Centers for Disease Control and Prevention. Atlanta, GA [Last updated Aug 2015; Accessed: Nov 2015]

Guerrant R, Van Gilder T, Steiner T, Thielman N, Slutsker L, Tauxe R, Hennessy T, Griffin P, DuPont H, Sack R, Tarr P, Neill M, Nachamkin I, Reller L, Osterholm M, Bennish M, Pickering L, Infectious Diseases Society of America. Practice guidelines for the management of infectious diarrhea. Clin Infect Dis. 2001; 32(3): 331-51. PubMed

Manatsathit S, DuPont H, Farthing M, Kositchaiwat C, Leelakusolvong S, Ramakrishna B, Sabra A, Speelman P, Surangsrirat S, Working Party of the Program Committ of the Bangkok World Congress of Gastroenterology 2002. Guideline for the management of acute diarrhea in adults. J Gastroenterol Hepatol. 2002; 17 Suppl: S54-71. PubMed

General References

Barr W, Smith A. Acute diarrhea. Am Fam Physician. 2014; 89(3): 180-9. PubMed

Bernstein D. Rotavirus overview. Pediatr Infect Dis J. 2009; 28(3 Suppl): S50-3. PubMed

Calderaro A, Gorrini C, Montecchini S, Peruzzi S, Piccolo G, Rossi S, Gargiulo F, Manca N, Dettori G, Chezzi C. Evaluation of a real-time polymerase chain reaction assay for the laboratory diagnosis of giardiasis. Diagn Microbiol Infect Dis. 2010; 66(3): 261-7. PubMed

DuPont H. Clinical practice. Bacterial diarrhea. N Engl J Med. 2009; 361(16): 1560-9. PubMed

Glass R, Parashar U, Estes M. Norovirus gastroenteritis. N Engl J Med. 2009; 361(18): 1776-85. PubMed

Graves N. Acute gastroenteritis. Prim Care. 2013; 40(3): 727-41. PubMed

Grimwood K, Forbes D. Acute and persistent diarrhea. Pediatr Clin North Am. 2009; 56(6): 1343-61. PubMed

Hill D, Ryan E. Management of travellers' diarrhoea. BMJ. 2008; 337: a1746. PubMed

Hunt J. Shiga toxin-producing Escherichia coli (STEC). Clin Lab Med. 2010; 30(1): 21-45. PubMed

Khan M, Bass D. Viral infections: new and emerging. Curr Opin Gastroenterol. 2010; 26(1): 26-30. PubMed

Mathis A, Weber R, Deplazes P. Zoonotic potential of the microsporidia. Clin Microbiol Rev. 2005; 18(3): 423-45. PubMed

Mead P, Slutsker L, Dietz V, McCaig L, Bresee J, Shapiro C, Griffin P, Tauxe R. Food-related illness and death in the United States. Emerg Infect Dis. 1999; 5(5): 607-25. PubMed

Patel M, Hall A, Vinjé J, Parashar U. Noroviruses: a comprehensive review. J Clin Virol. 2009; 44(1): 1-8. PubMed

Pawlowski S, Warren C, Guerrant R. Diagnosis and treatment of acute or persistent diarrhea. Gastroenterology. 2009; 136(6): 1874-86. PubMed

Pierce K, Kirkpatrick B. Update on human infections caused by intestinal protozoa. Curr Opin Gastroenterol. 2009; 25(1): 12-7. PubMed

Recommendations for Diagnosis of Shiga Toxin–Producing Escherichia coli Infections by Clinical Laboratories. October 16, 2009, Vol. 58, No. RR-12. Centers for Disease Control and Prevention. Atlanta, GA [Accessed: Nov 2015]

Steffen R, Hill D, DuPont H. Traveler's diarrhea: a clinical review. JAMA. 2015; 313(1): 71-80. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology

Couturier B, Hale D, Couturier M. Association of Campylobacter upsaliensis with persistent bloody diarrhea. J Clin Microbiol. 2012; 50(11): 3792-4. PubMed

Hymas W, Atkinson A, Stevenson J, Hillyard D. Use of modified oligonucleotides to compensate for sequence polymorphisms in the real-time detection of norovirus. J Virol Methods. 2007; 142(1-2): 10-4. PubMed

Khot P, Fisher M. Novel approach for differentiating Shigella species and Escherichia coli by matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Clin Microbiol. 2013; 51(11): 3711-6. PubMed

Rawlins M, Gerstner C, Hill H, Litwin C. Evaluation of a western blot method for the detection of Yersinia antibodies: evidence of serological cross-reactivity between Yersinia outer membrane proteins and Borrelia burgdorferi. Clin Diagn Lab Immunol. 2005; 12(11): 1269-74. PubMed

Shakespeare W, Davie D, Tonnerre C, Rubin M, Strong M, Petti C. Nalidixic acid-resistant Salmonella enterica serotype Typhi presenting as a primary psoas abscess: case report and review of the literature. J Clin Microbiol. 2005; 43(2): 996-8. PubMed

Medical Reviewers

Last Update: January 2016