Isosporiasis Treatment & Management

  • Author: Robert W Tolan Jr, MD; Chief Editor: Michael Stuart Bronze, MD   more...
 
Updated: Jun 29, 2011
 

Approach Considerations

In immunocompetent patients, isosporiasis is a mild protracted illness. In patients with AIDS, patients with malignancy, or in patients undergoing chemotherapy, isosporiasis can be debilitating or life-threatening. Hemorrhagic colitis occurs in rare cases.

Consultation with an infectious diseases specialist, a gastroenterologist, or both may be appropriate. Only patients with chronic isosporiasis associated with severe dehydration should require continued inpatient care. Transfer patients only if the required specialists and/or therapeutic measures are not available at the institution.

Although isosporiasis is generally a self-limited infection, patients who are treated tend to improve in 2-3 days, whereas those who are not treated remain sick considerably longer.

Immunocompetent hosts generally respond very rapidly to antiparasitic therapy, with symptomatic improvement within 5 days. Immunocompromised hosts also respond well, though less rapidly. However, these individuals relapse at a high rate (50% in 2 mo) once therapy is stopped. Such patients (eg, those with AIDS) may need life-long suppressive treatment with trimethoprim-sulfamethoxazole (TMP-SMZ).

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Supportive Care

Care is supportive and symptomatic. Antibiotics may be administered (see Pharmacologic Therapy). Fluid replacement and correction of electrolyte imbalance are helpful. Therapy for dehydration may be the most urgent intervention required. Fluid losses may range from 2-20 L/d. Patients with severe diarrhea may require hospitalization.

No specific diet is recommended in patients with isosporiasis, but a low-protein, lactose-free diet is advised until any diarrhea has resolved.

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Pharmacologic Therapy

For isosporiasis, unlike many of the protozoal infections that cause similar diseases, effective therapies are available.

Isosporiasis does not respond well to most antibiotics used to treat diarrhea. TMP-SMZ is the drug of choice because it is the best-studied and most readily available agent. Many patients with AIDS are already taking this agent as prophylaxis for Pneumocystis infection. One case report of isosporiasis refractory to TMP-SMZ has been described.[5]

Oral TMP-SMZ is well absorbed, even in patients with enteritis. A combination of 160 mg of TMP with 800 mg of SMZ (1 double-strength tablet PO q6h for 2-4 wk) is the preferred regimen. In patients who are intolerant to sulfonamides, pyrimethamine (50-75 mg PO q24h) with folinic acid (5-10 mg PO q24h) may be given for 2-4 weeks.

Patients with AIDS may require maintenance therapy for long-term suppression of I belli, typically in the form of 1 TMP-SMZ double-strength tablet 3 times a week. An alternative for long-term prophylaxis is pyrimethamine with sulfadiazine or sulfadoxine (eg, pyrimethamine 25 mg with sulfadoxine 500 mg 3 times a week), either of which should be accompanied by folinic acid. For patients who cannot tolerate sulfonamides, ciprofloxacin or pyrimethamine plus folinic acid may be nearly as effective for both acute treatment and prophylaxis.

Studies have proposed the veterinary agent diclazuril as a possible drug of choice if further investigation confirms its use and safety.[9] Doxycycline, roxithromycin, and nitazoxanide[10, 11] are reported to have some efficacy, but the clinical data available are insufficient to recommend their routine use at present.

Anecdotal case reports also document improvement with albendazole, bismuth subsalicylate, furazolidone, metronidazole, and quinacrine; again, however, clinical trials are lacking.

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Prevention

Isosporiasis is a food-borne and water-borne illness. Consequently, the practice of hygienic measures may help in preventing transmission. It is important to avoid possible exposure to contaminated food and water insofar as is possible.

Appropriate isolation measures should be used because shedding of oocysts may last for weeks.

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Contributor Information and Disclosures
Author

Robert W Tolan Jr, MD  Chief, Division of Allergy, Immunology and Infectious Diseases, The Children's Hospital at Saint Peter's University Hospital; Clinical Associate Professor of Pediatrics, Drexel University College of Medicine

Robert W Tolan Jr, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, Phi Beta Kappa, and Physicians for Social Responsibility

Disclosure: Novartis Honoraria Speaking and teaching

Coauthor(s)

Venkat R Minnaganti, MD  Consulting Staff, Department of Medicine, Winthrop University Hospital; Clinical Instructor, Department of Internal Medicine, Division of Infectious Disease, State University of New York School of Medicine at Stony Brook

Venkat R Minnaganti, MD is a member of the following medical societies: All India Ophthalmological Society, American College of Physicians, American Medical Association, American Society for Microbiology, and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Glenn Fennelly, MD, MPH  Director, Division of Infectious Diseases, Lewis M Fraad Department of Pediatrics, Jacobi Medical Center; Clinical Associate Professor of Pediatrics, Albert Einstein College of Medicine

Glenn Fennelly, MD, MPH is a member of the following medical societies: Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Klaus-Dieter Lessnau, MD, FCCP  Clinical Associate Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory; Director of Research in Pulmonary Medicine, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital

Klaus-Dieter Lessnau, MD, FCCP is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Medical Association, American Thoracic Society, and Society of Critical Care 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

John W King, MD  Professor of Medicine, Chief, Section of Infectious Diseases, Director, Viral Therapeutics Clinics for Hepatitis, Louisiana State University Health Sciences Center; Consultant in Infectious Diseases, Overton Brooks Veterans Affairs Medical Center

John W King, 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 for Microbiology, Association of Subspecialty Professors, Infectious Diseases Society of America, and Sigma Xi

Disclosure: emedicine $50.00 Author of chapter; MERCK None Other

Russell W Steele, MD  Head, Division of Pediatric Infectious Diseases, Ochsner Children's Health Center; Clinical Professor, Department of Pediatrics, Tulane University School of Medicine

Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, and Southern Medical Association

Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD  Professor, Stewart G Wolf Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center

Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Medical Association, Association of Professors of Medicine, Infectious Diseases Society of America, Oklahoma State Medical Association, and Southern Society for Clinical Investigation

Disclosure: Nothing to disclose.

References
  1. Woodcock HM. Notes on Protozoan parasites in the excreta. BMJ. 1915;2:709..

  2. Goodgame R. Emerging Causes of Traveler's Diarrhea: Cryptosporidium, Cyclospora, Isospora, and Microsporidia. Curr Infect Dis Rep. Feb 2003;5(1):66-73. [Medline].

  3. Sasaki M, Tanaka A, Nishimura T, Tsujikawa T, Andoh A, Ishizuka I, et al. A case of malabsorption syndrome caused by isosporiasis in an immunocompetent patient. J Gastroenterol. Jan 2004;39(1):88-9. [Medline].

  4. ten Hove RJ, van Lieshout L, Brienen EA, Perez MA, Verweij JJ. Real-time polymerase chain reaction for detection of Isospora belli in stool samples. Diagn Microbiol Infect Dis. Jul 2008;61(3):280-3. [Medline].

  5. Malik S, Samantaray JC, Bagga A, Das A. Refractory isosporiasis. Indian J Pediatr. May 2005;72(5):437-9. [Medline].

  6. Sorvillo FJ, Lieb LE, Seidel J, Kerndt P, Turner J, Ash LR. Epidemiology of isosporiasis among persons with acquired immunodeficiency syndrome in Los Angeles County. Am J Trop Med Hyg. Dec 1995;53(6):656-9. [Medline].

  7. Rowe JS, Shah SS, Motlhagodi S, Bafana M, Tawanana E, Truong HT, et al. An epidemiologic review of enteropathogens in Gaborone, Botswana: shifting patterns of resistance in an HIV endemic region. PLoS One. Jun 2 2010;5(6):e10924. [Medline]. [Full Text].

  8. DeHovitz JA, Pape JW, Boncy M, Johnson WD Jr. Clinical manifestations and therapy of Isospora belli infection in patients with the acquired immunodeficiency syndrome. N Engl J Med. Jul 10 1986;315(2):87-90. [Medline].

  9. Limson-Pobre RN, Merrick S, Gruen D, Soave R. Use of diclazuril for the treatment of isosporiasis in patients with AIDS. Clin Infect Dis. Jan 1995;20(1):201-2. [Medline].

  10. Fox LM, Saravolatz LD. Nitazoxanide: a new thiazolide antiparasitic agent. Clin Infect Dis. Apr 15 2005;40(8):1173-80. [Medline].

  11. Gilles HM, Hoffman PS. Treatment of intestinal parasitic infections: a review of nitazoxanide. Trends Parasitol. Mar 2002;18(3):95-7. [Medline].

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Oocyst of Isospora belli with 2 sporoblasts. From the Image Library, Division of Parasitic Diseases at the National Center for Infectious Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.
 
 
 
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