eMedicine Specialties > Infectious Diseases > Parasitic Infections
Isosporiasis: Treatment & Medication
Updated: Oct 24, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
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Treatment
Medical Care
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.
- Care is supportive and symptomatic.
- Antibiotics may be administered.
- Fluid losses may range from 2-20 L/d.
- Patients with severe diarrhea may require hospitalization.
Diet
- No specific diet is recommended in patients with isosporiasis.
- A low-protein, lactose-free diet is advised until the diarrhea has resolved.
Medication
Isosporiasis does not respond well to most antibiotics used to treat diarrhea. Oral TMP-SMZ is well absorbed, even in patients with enteritis. A combination of 160 mg TMP and 800 mg of SMZ (1 double-strength tablet PO q6h for 2-4 wk) is the preferred drug of choice. 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.
In patients with AIDS, maintenance therapy with long-term suppressive treatment may be necessary using 1 TMP-SMZ double-strength tablet 3 times a week. Alternatively, 25 mg of pyrimethamine with 500 mg of sulfadoxine 3 times a week may be given. Patients with AIDS tend to have high relapse rates but respond well to retreatment. In addition, fluid replacement and correction of electrolyte imbalance is helpful.
Anecdotal case reports document improvement with albendazole, bismuth subsalicylate, diclazuril, furazolidone, metronidazole, and quinacrine; however, clinical trials are lacking.
One case report of isosporiasis refractory to TMP-SMZ has been described.5
Antibiotics
Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.
Trimethoprim-sulfamethoxazole (Bactrim DS, Septra DS)
Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid.
Adult
1 DS tab (160 mg TMP/800 mg SMZ) PO q6h for 2-4 wk
Pediatric
Not established
May increase PT when used with warfarin (perform coagulation tests and adjust dose accordingly); coadministration with dapsone may increase blood levels of both drugs; coadministration of diuretics increases incidence of thrombocytopenia purpura in elderly people; phenytoin levels may increase with coadministration; may potentiate effects of methotrexate in bone marrow depression; hypoglycemic response to sulfonylureas may increase with coadministration; may increase levels of zidovudine; increased nephrotoxicity in renal transplant patients taking cyclosporine; decreased efficacy of tricyclic antidepressants
Documented hypersensitivity; megaloblastic anemia due to folate deficiency
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Discontinue at first appearance of sore throat, skin rash, or sign of adverse reaction; obtain CBCs frequently; discontinue therapy if significant hematologic changes occur; goiter, diuresis, and hypoglycemia may occur with sulfonamides; prolonged IV infusions or high doses may cause bone marrow depression (if signs occur, give 5-15 mg/d leucovorin); caution in folate deficiency (eg, chronic alcoholics, elderly people, those receiving anticonvulsant therapy, or those with malabsorption syndrome); hemolysis may occur in G-6-PD–deficient individuals; patients with AIDS may not tolerate or respond to TMP-SMZ; caution in renal or hepatic impairment (perform urinalyses and renal function tests during therapy), hyperkalemia; give fluids to prevent crystalluria and stone formation; avoid use in pregnant patients and nursing mothers
Rare fatalities due to Stevens-Johnson syndrome, fulminant hepatic necrosis, agranulocytosis, and aplastic anemia have occurred
Pyrimethamine (Daraprim)
Folic acid antagonist that selectively inhibits plasmodial dihydrofolate reductase.
Adult
50-75 mg PO qd for 10 d, then 25 mg PO qd as maintenance dosage
Pediatric
Not established
Concurrent use of antifolic acids (eg, methotrexate, pyrimethamine) may increase risk of bone marrow suppression; discontinue pyrimethamine therapy if signs of folate deficiency develop; mild hepatotoxicity may occur with concomitant administration of lorazepam and pyrimethamine
Documented hypersensitivity; megaloblastic anemia resulting from a folate deficiency
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
If signs of folate deficiency develop, reduce dose or discontinue drug depending on patient response; caution in hepatic or renal impairment; monitor for toxoplasmosis by performing semiweekly blood counts, including platelet counts; may precipitate hemolytic anemia in G-6-PD deficiency, generally in presence of other stressful events
Stop medication at onset of a rash, sore throat, pallor, purpura, or glossitis
Vitamins
These agents are used to correct folic acid deficiency resulting from use of folic acid antagonists.
Folinic acid; leucovorin (Wellcovorin)
A derivative of folic acid, which is used with folic acid antagonists such as sulfonamides and pyrimethamine.
Adult
5-10 mg PO qd
Pediatric
Not established
May decrease efficacy of phenobarbital, phenytoin, primidone
Documented hypersensitivity; pernicious anemia or vitamin-deficient megaloblastic anemias
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Do not administer intrathecally or intraventricularly
More on Isosporiasis |
| Overview: Isosporiasis |
| Differential Diagnoses & Workup: Isosporiasis |
 Treatment & Medication: Isosporiasis |
| Follow-up: Isosporiasis |
| Multimedia: Isosporiasis |
| References |
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References
Woodcock HM. Notes on Protozoan parasites in the excreta. BMJ. 1915;2:709.
Goodgame R. Emerging Causes of Traveler's Diarrhea: Cryptosporidium, Cyclospora, Isospora, and Microsporidia. Curr Infect Dis Rep. Feb 2003;5(1):66-73. [Medline].
Sasaki M, Tanaka A, Nishimura T, et al. A case of malabsorption syndrome caused by isosporiasis in an immunocompetent patient. J Gastroenterol. Jan 2004;39(1):88-9. [Medline].
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].
Malik S, Samantaray JC, Bagga A. Refractory isosporiasis. Indian J Pediatr. May 2005;72(5):437-9. [Medline].
Ackers JP. Gut Coccidia--Isospora, Cryptosporidium, Cyclospora and Sarcocystis. Semin Gastrointest Dis. Jan 1997;8(1):33-44. [Medline].
Benator DA, French AL, Beaudet LM, et al. Isospora belli infection associated with acalculous cholecystitis in a patient with AIDS. Ann Intern Med. Nov 1 1994;121(9):663-4. [Medline].
Bernard E, Delgiudice P, Carles M, et al. Disseminated isosporiasis in an AIDS patient. Eur J Clin Microbiol Infect Dis. Sep 1997;16(9):699-701. [Medline].
Cimerman S, Cimerman B, Lewi DS. Prevalence of intestinal parasitic infections in patients with acquired immunodeficiency syndrome in Brazil. Int J Infect Dis. Summer 1999;3(4):203-6. [Medline].
Collins JP, Keller KF, Brown L. "Ghost" forms of Giardia lamblia cysts initially misdiagnosed as Isospora. Am J Trop Med Hyg. Jul 1978;27(4):835-6. [Medline].
DeHovitz JA, Pape JW, Boncy M, et al. 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].
Deluol AM, Mechali D, Cenac J, et al. Incidence and clinical aspects of intestinal coccidiosis in a tropical medicine practice. Bull Soc Pathol Exot Filiales. May-Jun 1980;73(3):259-65. [Medline].
Dionisio D, Santucci M, Comin CE, et al. [Isosporiasis and sarcocystosis. The current findings]. Recenti Prog Med. Dec 1992;83(12):719-25. [Medline].
Forthal DN, Guest SS. Isospora belli enteritis in three homosexual men. Am J Trop Med Hyg. Nov 1984;33(6):1060-4. [Medline].
Gellin BG, Soave R. Coccidian infections in AIDS. Toxoplasmosis, cryptosporidiosis, and isosporiasis. Med Clin North Am. Jan 1992;76(1):205-34. [Medline].
Girard PM, Marche C, Maslo C, et al. [Digestive manifestations in acquired immunodeficiency disease]. Ann Med Interne (Paris). 1987;138(6):411-5. [Medline].
Goodgame RW. Understanding intestinal spore-forming protozoa: cryptosporidia, microsporidia, isospora, and cyclospora. Ann Intern Med. Feb 15 1996;124(4):429-41. [Medline].
Heyworth MF. Parasitic diseases in immunocompromised hosts. Cryptosporidiosis, isosporiasis, and strongyloidiasis. Gastroenterol Clin North Am. Sep 1996;25(3):691-707. [Medline].
Hizawa K, Iida M, Eguchi K, et al. Comparative features of double-contrast barium studies in patients with isosporiasis and strongyloidiasis. Clin Radiol. Oct 1998;53(10):764-7. [Medline].
Hu DJ, Fleming PL, Castro KG, et al. How important is race/ethnicity as an indicator of risk for specific AIDS-defining conditions?. J Acquir Immune Defic Syndr Hum Retrovirol. Nov 1 1995;10(3):374-80. [Medline].
Hunter G, Bagshawe AF, Baboo KS, et al. Intestinal parasites in Zambian patients with AIDS. Trans R Soc Trop Med Hyg. Sep-Oct 1992;86(5):543-5. [Medline].
Kaplan JE, Hu DJ, Holmes KK, et al. Preventing opportunistic infections in human immunodeficiency virus-infected persons: implications for the developing world. Am J Trop Med Hyg. Jul 1996;55(1):1-11. [Medline].
Klepser ME, Klepser TB. Drug treatment of HIV-related opportunistic infections. Drugs. Jan 1997;53(1):40-73. [Medline].
Knight R. Giardiasis, isosporiasis and balantidiasis. Clin Gastroenterol. Jan 1978;7(1):31-47. [Medline].
Lanjewar DN, Rodrigues C, Saple DG, et al. Cryptosporidium, isospora and strongyloides in AIDS. Natl Med J India. Jan-Feb 1996;9(1):17-9. [Medline].
Leonard M, Payne R, Chhabra A, Gritter NJ. Isosporiasis presenting with failure to thrive. Tenn Med. Sep 1997;90(9):372-3. [Medline].
Levine GI. Parasitic diseases. Diseases associated with acquired immunodeficiency syndrome. Prim Care. Mar 1991;18(1):129-52. [Medline].
Lindsay DS, Dubey JP, Blagburn BL. Biology of Isospora spp. from humans, nonhuman primates, and domestic animals. Clin Microbiol Rev. Jan 1997;10(1):19-34. [Medline].
Lindsay DS, Dubey JP, Toivio-Kinnucan MA, Gritter NJ. Examination of extraintestinal tissue cysts of Isospora belli. J Parasitol. Aug 1997;83(4):620-5. [Medline].
Mannheimer SB, Soave R. Protozoal infections in patients with AIDS. Cryptosporidiosis, isosporiasis, cyclosporiasis, and microsporidiosis. Infect Dis Clin North Am. Jun 1994;8(2):483-98. [Medline].
Michiels JF, Hofman P, Bernard E, et al. Intestinal and extraintestinal Isospora belli infection in an AIDS patient. A second case report. Pathol Res Pract. Nov 1994;190(11):1089-93; discussion 1094. [Medline].
Michiels JF, Saint Paul MC, Hofman P, et al. [Histopathologic features of opportunistic infections of the small intestine in acquired immunodeficiency syndrome]. Ann Pathol. 1992;12(3):165-73. [Medline].
Nahlen BL, Chu SY, Nwanyanwu OC, et al. HIV wasting syndrome in the United States. AIDS. Feb 1993;7(2):183-8. [Medline].
Ng E, Markell EK, Fleming RL, et al. Demonstration of Isospora belli by acid-fast stain in a patient with acquired immune deficiency syndrome. J Clin Microbiol. Sep 1984;20(3):384-6. [Medline].
Pape JW, Johnson WD Jr. Isospora belli infections. Prog Clin Parasitol. 1991;2:119-27. [Medline].
Pape JW, Verdier RI, Boncy M, et al. Cyclospora infection in adults infected with HIV. Clinical manifestations, treatment, and prophylaxis. Ann Intern Med. Nov 1 1994;121(9):654-7. [Medline].
Pape JW, Verdier RI, Johnson WD Jr. Treatment and prophylaxis of Isospora belli infection in patients with the acquired immunodeficiency syndrome. N Engl J Med. Apr 20 1989;320(16):1044-7. [Medline].
Restrepo C, Macher AM, Radany EH. Disseminated extraintestinal isosporiasis in a patient with acquired immune deficiency syndrome. Am J Clin Pathol. Apr 1987;87(4):536-42. [Medline].
Selik RM, Karon JM, Ward JW. Effect of the human immunodeficiency virus epidemic on mortality from opportunistic infections in the United States in 1993. J Infect Dis. Sep 1997;176(3):632-6. [Medline].
Soave R. Cryptosporidiosis and isosporiasis in patients with AIDS. Infect Dis Clin North Am. Jun 1988;2(2):485-93. [Medline].
Soave R. Cyclospora: an overview. Clin Infect Dis. Sep 1996;23(3):429-35; quiz 436-7. [Medline].
Sorvillo FJ, Lieb LE, Seidel J, et al. 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].
Steinmann E, di Gallo A, Ruttimann S, et al. [Etiology of diarrheal diseases in immunocompetent and HIV-positive patients]. Schweiz Med Wochenschr. Sep 1 1990;120(35):1253-6. [Medline].
Sun T. Current topics in protozoal diseases. Am J Clin Pathol. Jul 1994;102(1):16-29. [Medline].
Trier JS, Moxey PC, Schimmel EM, et al. Chronic intestinal coccidiosis in man: intestinal morphology and response to treatment. Gastroenterology. May 1974;66(5):923-35. [Medline].
Varea M, Clavel A, Doiz O, et al. Fuchsin fluorescence and autofluorescence in Cryptosporidium, Isospora and Cyclospora oocysts. Int J Parasitol. Dec 1998;28(12):1881-3. [Medline].
Verdier RI, Fitzgerald DW, Johnson WD Jr, et al. Trimethoprim-sulfamethoxazole compared with ciprofloxacin for treatment and prophylaxis of Isospora belli and Cyclospora cayetanensis infection in HIV-infected patients. A randomized, controlled trial. Ann Intern Med. Jun 6 2000;132(11):885-8. [Medline].
Weiss LM, Keohane EM. The uncommon gastrointestinal Protozoa: Microsporidia, Blastocystis, Isospora, Dientamoeba, and Balantidium. Curr Clin Top Infect Dis. 1997;17:147-87. [Medline].
Weiss LM, Perlman DC, Sherman J, et al. Isospora belli infection: treatment with pyrimethamine. Ann Intern Med. Sep 15 1988;109(6):474-5. [Medline].
Westerman EL, Christensen RP. Chronic Isospora belli infection treated with co-trimoxazole. Ann Intern Med. Sep 1979;91(3):413-4. [Medline].
Whiteside ME, Barkin JS, May RG, et al. Enteric coccidiosis among patients with the acquired immunodeficiency syndrome. Am J Trop Med Hyg. Nov 1984;33(6):1065-72. [Medline].
Wittner M, Tanowitz HB, Weiss LM. Parasitic infections in AIDS patients. Cryptosporidiosis, isosporiasis, microsporidiosis, cyclosporiasis. Infect Dis Clin North Am. Sep 1993;7(3):569-86. [Medline].
Further Reading
Keywords
isosporiasis, Isospora belli, I belli, Isospora belli infection, I belli infection, extraintestinal isosporiasis, disseminated isosporiasis, intestinal parasitic infections, Isospora belli enteritis, I belli enteritis, Cryptosporidium, Cyclospora, Toxoplasma
