Cryptosporidiosis Workup

Author: Miguel M Cabada, MD; Chief Editor: Burke A Cunha, MD more...

Updated: Jun 3, 2011

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Approach Considerations
Stool Tests
Urea, Electrolyte, and Liver Function Tests
Lymphocyte Subset Analysis
HIV Testing
Abdominal Ultrasonography and ERCP
Histologic Findings
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Approach Considerations

Most laboratories do not routinely test for Cryptosporidium, and many laboratories use insensitive tests when testing for this organism .^[1]Studies in the United States have documented cryptosporidiosis in about 4% of stools sent for parasitologic examination,^[5]while overall, about 13% of stool studies submitted for parasitologic studies in developing countries reveal Cryptosporidium oocysts.

Also see Pediatric Cryptosporidiosis.

Stool Tests

Modified acid-fast staining of stool shows red-stained, round oocysts against a blue-green background, as seen in the image below. White and red blood cells should not be seen in the stool. Antigen-detection assays are more sensitive and include immunofluorescent assays, enzyme-linked immunosorbent assay (ELISA), and immunochromatographic tests. Polymerase chain reaction (PCR) assays, when available, are more sensitive than other tests.^[11]

Perform a stool culture to rule out the presence of bacterial pathogens.

Urea, Electrolyte, and Liver Function Tests

Urea and electrolyte tests are used to assess electrolyte replacement requirements and the presence of prerenal uremia.

Elevated alkaline phosphatase and glutamyl transpeptidase without hyperbilirubinemia are typical signs of biliary infection.

Lymphocyte Subset Analysis

CD4⁺ lymphocyte counts predict the duration of disease in patients infected with HIV. When the counts are greater than 150 cells/μL, the diarrhea is likely to resolve spontaneously, but diarrhea may be chronic with lower counts. Counts are typically less than 50 cells/μL in patients with either biliary involvement or choleralike syndromes.

HIV Testing

Prolonged diarrhea caused by cryptosporidiosis may warrant HIV testing. Provide appropriate counseling before and after administration of the HIV test.

Abdominal Ultrasonography and ERCP

Dilated or irregular intrahepatic and extrahepatic bile ducts, along with a thickened gallbladder, as detected with abdominal ultrasonography, indicate biliary involvement.

Endoscopic retrograde cholangiopancreatography (ERCP) is often needed to diagnose sclerosing cholangitis or papillary stenosis.

ERCP identification of Cryptosporidium oocysts in bile or intracellular forms on biopsy confirms the diagnosis of biliary cryptosporidiosis. Papillary stenosis may be present and responds symptomatically to endoscopic sphincterotomy, often with stent placement.

Histologic Findings

Histologic examination of the small intestine is not required to confirm the diagnosis of cryptosporidiosis. The small intestine shows the parasite projecting from the brush border of the mucosal surface. Parasites may also be identified in bile or biliary tract biopsies.

Proceed to Treatment & Management

Contributor Information and Disclosures

Author

Miguel M Cabada, MD Fellow in Infectious Diseases, University of Texas Medical Branch School of Medicine

Miguel M Cabada, MD is a member of the following medical societies: Infectious Diseases Society of America, International Society for Infectious Diseases, and International Society of Travel Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

A Clinton White Jr, MD The Paul R Stalnaker, MD, Distinguished Professor of Internal Medicine, Director, Infectious Disease Division, Department of Internal Medicine, University of Texas Medical Branch School of Medicine

A Clinton White Jr, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Federation for Medical Research, American Society of Tropical Medicine and Hygiene, Christian Medical & Dental Society, and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Specialty Editor Board

Jeffrey D Band, MD Professor of Medicine, Oakland University William Beaumont School of Medicine; Director, Division of Infectious Diseases and International Medicine, Corporate Epidemiologist, William Beaumont Hospital; Clinical Professor of Medicine, Wayne State University School of Medicine

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Joseph F John Jr, MD, FACP, FIDSA, FSHEA Clinical Professor of Medicine, Molecular Genetics and Microbiology, Medical University of South Carolina College of Medicine; Associate Chief of Staff for Education, Ralph H Johnson Veterans Affairs Medical Center

Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital

Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Acknowledgments

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous author Damon Eisen, MD, to the development and writing of the source article.

References

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