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Toxoplasmosis in immunocompetent hosts

Howard M Heller, MD, MPH
Section Editor
Peter F Weller, MD, FACP
Deputy Editor
Jennifer Mitty, MD, MPH


Toxoplasmosis, an infection with a worldwide distribution, is caused by the intracellular protozoan parasite, Toxoplasma gondii. Immunocompetent persons with primary infection are usually asymptomatic, but latent infection can persist for the life of the host. However, there is a risk of reactivating infection at a later time should the individual become immunocompromised, even if infection was asymptomatic or only mildly symptomatic initially. (See "Toxoplasmosis in HIV-infected patients".)

Toxoplasmosis in immunocompetent persons will be reviewed here. Toxoplasmosis in HIV-infected and pregnant patients and congenital and ocular toxoplasmosis are discussed separately. (See "Toxoplasmosis and pregnancy" and "Overview of TORCH infections" and "Retinal vasculitis associated with systemic disorders and infections".)


Transmission — Felines are the only animals in which T. gondii can complete its reproductive cycle [1]. Following feline ingestion of any of the forms of T. gondii, the parasite infects the gut epithelial cells and reproduces. The feline then excretes infectious oocysts in feces.

When non-felines, including humans, ingest T. gondii oocysts, the organisms invade intestinal epithelium and disseminate throughout the body. They then encyst in any type of nucleated cell and can lie dormant within tissues for the life of the host.

There are four means of acquiring toxoplasmosis in humans [1]:


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Literature review current through: Sep 2016. | This topic last updated: Feb 28, 2014.
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  1. Tenter AM, Heckeroth AR, Weiss LM. Toxoplasma gondii: from animals to humans. Int J Parasitol 2000; 30:1217.
  2. Baril L, Ancelle T, Goulet V, et al. Risk factors for Toxoplasma infection in pregnancy: a case-control study in France. Scand J Infect Dis 1999; 31:305.
  3. Rai SK, Matsumura T, Ono K, et al. High Toxoplasma seroprevalence associated with meat eating habits of locals in Nepal. Asia Pac J Public Health 1999; 11:89.
  4. Cook AJ, Gilbert RE, Buffolano W, et al. Sources of toxoplasma infection in pregnant women: European multicentre case-control study. European Research Network on Congenital Toxoplasmosis. BMJ 2000; 321:142.
  5. Jones JL, Dargelas V, Roberts J, et al. Risk factors for Toxoplasma gondii infection in the United States. Clin Infect Dis 2009; 49:878.
  6. Jones JL, Kruszon-Moran D, Sanders-Lewis K, Wilson M. Toxoplasma gondii infection in the United States, 1999 2004, decline from the prior decade. Am J Trop Med Hyg 2007; 77:405.
  7. Pappas G, Roussos N, Falagas ME. Toxoplasmosis snapshots: global status of Toxoplasma gondii seroprevalence and implications for pregnancy and congenital toxoplasmosis. Int J Parasitol 2009; 39:1385.
  8. Remington JS. Toxoplasmosis in the adult. Bull N Y Acad Med 1974; 50:211.
  9. McCabe RE, Brooks RG, Dorfman RF, Remington JS. Clinical spectrum in 107 cases of toxoplasmic lymphadenopathy. Rev Infect Dis 1987; 9:754.
  10. O'Connell S, Guy EC, Dawson SJ, et al. Chronic active toxoplasmosis in an immunocompetent patient. J Infect 1993; 27:305.
  11. Sheagren JN, Lunde MN, Simon HB. Chronic lymphadenopathic toxoplasmosis. A case with marked hyperglobulinemia and impaired delayed hypersensitivity responses during active infection. Am J Med 1976; 60:300.
  12. Leal FE, Cavazzana CL, de Andrade HF Jr, et al. Toxoplasma gondii pneumonia in immunocompetent subjects: case report and review. Clin Infect Dis 2007; 44:e62.
  13. Montoya JG, Jordan R, Lingamneni S, et al. Toxoplasmic myocarditis and polymyositis in patients with acute acquired toxoplasmosis diagnosed during life. Clin Infect Dis 1997; 24:676.
  14. Chandenier J, Jarry G, Nassif D, et al. Congestive heart failure and myocarditis after seroconversion for toxoplasmosis in two immunocompetent patients. Eur J Clin Microbiol Infect Dis 2000; 19:375.
  15. Franco-Paredes C, Rouphael N, Méndez J, et al. Cardiac manifestations of parasitic infections. Part 2: Parasitic myocardial disease. Clin Cardiol 2007; 30:218.
  16. Cunningham T. Pancarditis in acute toxoplasmosis. Am J Clin Pathol 1982; 78:403.
  17. Behan WM, Behan PO, Draper IT, Williams H. Does Toxoplasma cause polymyositis? Report of a case of polymyositis associated with toxoplasmosis and a critical review of the literature. Acta Neuropathol 1983; 61:246.
  18. Calore EE, Minkovski R, Khoury Z, et al. Skeletal muscle pathology in 2 siblings infected with Toxoplasma gondii. J Rheumatol 2000; 27:1556.
  19. Holland GN, Crespi CM, ten Dam-van Loon N, et al. Analysis of recurrence patterns associated with toxoplasmic retinochoroiditis. Am J Ophthalmol 2008; 145:1007.
  20. Montoya JG, Remington JS. Toxoplasmic chorioretinitis in the setting of acute acquired toxoplasmosis. Clin Infect Dis 1996; 23:277.
  21. Dorfman RF, Remington JS. Value of lymph-node biopsy in the diagnosis of acute acquired toxoplasmosis. N Engl J Med 1973; 289:878.
  22. Weiss LM, Chen YY, Berry GJ, et al. Infrequent detection of Toxoplasma gondii genome in toxoplasmic lymphadenitis: a polymerase chain reaction study. Hum Pathol 1992; 23:154.
  23. Zaharopoulos P. Demonstration of parasites in toxoplasma lymphadenitis by fine-needle aspiration cytology: report of two cases. Diagn Cytopathol 2000; 22:11.
  24. REMINGTON JS, BARNETT CG, MEIKEL M, LUNDE MN. Toxoplasmosis and infectious mononucleosis. Arch Intern Med 1962; 110:744.
  25. Remington JS, Thulliez P, Montoya JG. Recent developments for diagnosis of toxoplasmosis. J Clin Microbiol 2004; 42:941.
  26. Gras L, Gilbert RE, Wallon M, et al. Duration of the IgM response in women acquiring Toxoplasma gondii during pregnancy: implications for clinical practice and cross-sectional incidence studies. Epidemiol Infect 2004; 132:541.
  27. Wilson M, Remington JS, Clavet C, et al. Evaluation of six commercial kits for detection of human immunoglobulin M antibodies to Toxoplasma gondii. The FDA Toxoplasmosis Ad Hoc Working Group. J Clin Microbiol 1997; 35:3112.
  28. Montoya J, Boothroyd J, Kovacs J. Toxoplasma gondii. In: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Seventh Ed, 2010. Vol 2, p.3495.
  29. Reiter-Owona I, Petersen E, Joynson D, et al. The past and present role of the Sabin-Feldman dye test in the serodiagnosis of toxoplasmosis. Bull World Health Organ 1999; 77:929.
  30. Balsari A, Poli G, Molina V, et al. ELISA for toxoplasma antibody detection: a comparison with other serodiagnostic tests. J Clin Pathol 1980; 33:640.
  31. Walton BC, Benchoff BM, Brooks WH. Comparison of the indirect fluorescent antibody test and methylene blue dye test for detection of antibodies to Toxoplasma gondii. Am J Trop Med Hyg 1966; 15:149.
  32. Thulliez P, Remington JS, Santoro F, et al. [A new agglutination reaction for the diagnosis of the developmental stage of acquired toxoplasmosis]. Pathol Biol (Paris) 1986; 34:173.
  33. Liesenfeld O, Montoya JG, Kinney S, et al. Effect of testing for IgG avidity in the diagnosis of Toxoplasma gondii infection in pregnant women: experience in a US reference laboratory. J Infect Dis 2001; 183:1248.
  34. Zotti C, Charrier L, Giacomuzzi M, et al. Use of IgG Avidity test in case definitions of toxoplasmosis in pregnancy. New Microbiol 2004; 27:17.
  35. Candolfi E, Pastor R, Huber R, et al. IgG avidity assay firms up the diagnosis of acute toxoplasmosis on the first serum sample in immunocompetent pregnant women. Diagn Microbiol Infect Dis 2007; 58:83.
  36. Derouin F, Thulliez P, Candolfi E, et al. Early prenatal diagnosis of congenital toxoplasmosis using amniotic fluid samples and tissue culture. Eur J Clin Microbiol Infect Dis 1988; 7:423.
  37. Angel SO, Matrajt M, Margarit J, et al. Screening for active toxoplasmosis in patients by DNA hybridization with the ABGTg7 probe in blood samples. J Clin Microbiol 1997; 35:591.
  38. Rothova A, de Boer JH, Ten Dam-van Loon NH, et al. Usefulness of aqueous humor analysis for the diagnosis of posterior uveitis. Ophthalmology 2008; 115:306.
  39. Dedicoat M, Livesley N. Management of toxoplasmic encephalitis in HIV-infected adults (with an emphasis on resource-poor settings). Cochrane Database Syst Rev 2006; :CD005420.
  40. http://www.cdc.gov/parasites/toxoplasmosis/health_professionals/index.html#tx.