eMedicine Specialties > Infectious Diseases > Parasitic Infections

Cryptosporidiosis

Author: 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
Contributor Information and Disclosures

Updated: Jun 23, 2008

Introduction

Background

Human cryptosporidiosis is caused by infection with the Apicomplexa protozoans of the genus Cryptosporidium. Human illness was formerly thought to be caused by a single species, but recent molecular studies have demonstrated that several different species cause human cryptosporidiosis.1,2,3,4,5 Among the more common species are Cryptosporidium hominis, for which humans are the only natural host, and Cryptosporidium parvum, which infects bovines as well as humans.

Cryptosporidiosis mainly affects children. It causes a self-limited diarrheal illness in healthy individuals. Cryptosporidiosis is also recognized as a cause of persistent diarrhea in children and severe prolonged diarrhea in persons with AIDS. The source of most endemic cryptosporidiosis cases is human-to-human fecal-oral transmission, but infection may also result from animal-to-person transmission and waterborne transmission. Major outbreaks resulting from waterborne transmission have been recorded.

Pathophysiology

Cryptosporidium oocysts are highly infectious, requiring only 101 -103 oocysts to cause human disease (50% infectious dose, 102). The oocysts are infectious immediately, and the life cycle of the parasite produces forms that invade the intestine. The location of the parasite in the intestine is intracellular but extracytoplasmic, which may contribute to the marked resistance of Cryptosporidium species to treatment. Large numbers of oocysts are excreted and are resistant to harsh conditions, including chlorine at levels usually applied in water treatment.

The mechanism by which Cryptosporidium causes diarrhea includes a combination of increased intestinal permeability, chloride secretion, and malabsorption, which are all thought to be caused by the host response to infection. In immunocompetent persons, the infection is usually limited to the small intestines. In persons with AIDS or certain congenital immunodeficiencies, the biliary tract may be involved.

Frequency

United States

The frequency of cryptosporidiosis has not been well-defined. About 30% of the adult population of the United States is seropositive. The number of cases diagnosed has increased with improved diagnostic testing, with over 8,000 cases reported in 2005. Still, most laboratories do not routinely test for this organism, and many laboratories use insensitive tests when testing for Cryptosporidium. 1 Recent studies have documented cryptosporidiosis in about 4% of stools sent for parasitologic examination.6 Prior to the availability of highly active antiretroviral therapy, approximately 10-15% of patients with AIDS developed cryptosporidiosis over their lifetime. Like other opportunistic infections, the prevalence of cryptosporidiosis in AIDS patients has dropped dramatically.

International

In developing countries, most people are infected as children. For example, studies in Brazil documented 90% of children in slums were infected before age 5 years. Serologic and stool studies have documented high rates of infection in Latin America, Africa, the Middle East, and South Asia. Overall, about 13% of stool studies submitted for parasitologic studies in developing countries reveal Cryptosporidium oocysts. In persons with AIDS, the rate of cryptosporidiosis is higher in developing countries, ranging from 12-48% of those with diarrhea.1,2,3

Mortality/Morbidity

Cryptosporidiosis is an important cause of persistent diarrhea in developing countries. Children with persistent diarrhea develop worsening malnutrition, which may result in cognitive and fitness problems that persist for years. Chronic cryptosporidiosis may be complicated by biliary tract disease, malabsorption, and death in individuals with AIDS and malnourished children.

Age

The peak incidence of cryptosporidiosis is in children younger than 5 years. Infection is rare in immunocompetent adults in developing countries but can occur in persons with AIDS.

Clinical

History

After an incubation period of 5-10 days (range 2-28 d), an infected individual develops watery diarrhea, which may be associated with abdominal cramps and a low-grade fever. Parasitologically diagnosed cases typically last for about 5-10 days and may persist for 2-4 weeks. Individuals with AIDS and very low CD4 cell counts may develop a profuse, choleralike diarrhea, which can be complicated by volume depletion and malabsorption. Biliary tract involvement is seen in persons with AIDS who have very low CD4 cell counts and is common in children with X-linked immunodeficiency with hyper–immunoglobulin M (IgM). Biliary involvement may include acalculous cholecystitis, sclerosing cholangitis, papillary stenosis, or pancreatitis. All are associated with right upper quadrant pain, nausea, and vomiting.

Physical

Physical findings are nonspecific. Temperature higher than 39°C is not characteristic of cryptosporidiosis and warrants investigation for other infections. Patient may have signs of volume depletion or wasting from malabsorption.

More on Cryptosporidiosis

Overview: Cryptosporidiosis
Differential Diagnoses & Workup: Cryptosporidiosis
Treatment & Medication: Cryptosporidiosis
Follow-up: Cryptosporidiosis
Multimedia: Cryptosporidiosis
References
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References

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  2. Bushen OY, Lima AA, Guerrant RL. Cryptosporidiosis. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical Infectious Diseases. Philadelphia, PA: Elsevier-Churchill Livingstone Principle, Pathogens, and Practice.; 2006:1003-1014.

  3. Kosek M, Alcantara C, Lima AA, Guerrant RL. Cryptosporidiosis: an update. Lancet Infect Dis. Nov 2001;1(4):262-9. [Medline].

  4. Ramirez NE, Ward LA, Sreevatsan S. A review of the biology and epidemiology of cryptosporidiosis in humans and animals. Microbes Infect. Jul 2004;6(8):773-85. [Medline].

  5. Thompson RC, Olson ME, Zhu G, Enomoto S, Abrahamsen MS, Hijjawi NS. Cryptosporidium and cryptosporidiosis. Adv Parasitol. 2005;59:77-158. [Medline].

  6. Amin OM. Seasonal prevalence of intestinal parasites in the United States during 2000. Am J Trop Med Hyg. Jun 2002;66(6):799-803. [Medline].

  7. Amadi B, Mwiya M, Musuku J, Watuka A, Sianongo S, Ayoub A, et al. Effect of nitazoxanide on morbidity and mortality in Zambian children with cryptosporidiosis: a randomised controlled trial. Lancet. Nov 2 2002;360(9343):1375-80. [Medline].

  8. Rossignol JF, Kabil SM, el-Gohary Y, Younis AM. Effect of nitazoxanide in diarrhea and enteritis caused by Cryptosporidium species. Clin Gastroenterol Hepatol. Mar 2006;4(3):320-4. [Medline].

  9. Rossignol JF, Ayoub A, Ayers MS. Treatment of diarrhea caused by Cryptosporidium parvum: a prospective randomized, double-blind, placebo-controlled study of Nitazoxanide. J Infect Dis. Jul 1 2001;184(1):103-6. [Medline].

  10. Kotler DP, Fogleman L, Tierney AR. Comparison of total parenteral nutrition and an oral, semielemental diet on body composition, physical function, and nutrition-related costs in patients with malabsorption due to acquired immunodeficiency syndrome. JPEN J Parenter Enteral Nutr. May-Jun 1998;22(3):120-6. [Medline].

  11. Smith HV, Corcoran GD. New drugs and treatment for cryptosporidiosis. Curr Opin Infect Dis. Dec 2004;17(6):557-64. [Medline].

  12. Blackburn BG, Mazurek JM, Hlavsa M, Park J, Tillapaw M, Parrish M. Cryptosporidiosis associated with ozonated apple cider. Emerg Infect Dis. Apr 2006;12(4):684-6. [Medline].

  13. Buch K, Nguyen S, Divino CM, Weber K, Morotti RA. Cryptosporidiosis presenting as acute appendicitis: a case report. Am Surg. Jun 2005;71(6):537-8. [Medline].

  14. Cunha BA. Antibiotic Essentials. 5th ed. Royal Oak, Mich: Physicians Press; 2006.

  15. Insulander M, Lebbad M, Stenström TA, Svenungsson B. An outbreak of cryptosporidiosis associated with exposure to swimming pool water. Scand J Infect Dis. 2005;37(5):354-60. [Medline].

  16. Mac Kenzie WR, Hoxie NJ, Proctor ME, Gradus MS, Blair KA, Peterson DE, et al. A massive outbreak in Milwaukee of cryptosporidium infection transmitted through the public water supply. N Engl J Med. Jul 21 1994;331(3):161-7. [Medline].

  17. Mahdi NK, Ali NH. Cryptosporidiosis and other intestinal parasitic infections in patients with chronic diarrhea. Saudi Med J. Sep 2004;25(9):1204-7. [Medline].

  18. Roy SL, DeLong SM, Stenzel SA, Shiferaw B, Roberts JM, Khalakdina A. Risk factors for sporadic cryptosporidiosis among immunocompetent persons in the United States from 1999 to 2001. J Clin Microbiol. Jul 2004;42(7):2944-51. [Medline].

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Further Reading

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Keywords

cryptosporidiosis, biliary cryptosporidiosis, calf scours, slim disease, Cryptosporidium parvum, C parvum, Cryptosporidium hominis, C hominis, cryptosporidia, Apicomplexa protozoan, diarrhea, abdominal cramps, low-grade fever, acalculous cholecystitis, sclerosing cholangitis, papillary stenosis, pancreatitis

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Contributor Information and Disclosures

Author

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
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.

Medical Editor

Jeffrey D Band, MD, Clinical Professor of Medicine, Wayne State University School of Medicine; Director, Division of Infectious Diseases and International Medicine, William Beaumont Hospital Corporation
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Joseph F John Jr, MD, FACP, FIDSA, FSHEA, Clinical Professor of Medicine, Molecular Genetics and Microbiology, Medical University of South Carolina; Associate Chief of Staff for Education, Ralph H Johnson Veterans Affairs Medical Center
Disclosure: BioMerieux Honoraria Review panel membership; Cubist Honoraria Review panel membership; Pfizer Honoraria Speaking and teaching; Merck Stock dividends stock holdings

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
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.

 
 
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