Toxoplasma

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Toxoplasma gondii
T. gondii tachyzoites
Scientific classification
Kingdom: Protista
Phylum: Apicomplexa
Class: Conoidasida
Subclass: Coccidiasina
Order: Eucoccidiorida
Family: Sarcocystidae
Genus: Toxoplasma
Binomial name
Toxoplasma gondii

Toxoplasma gondii is a protozoan parasite that can infect almost all warm-blooded animals, including humans.[1][2]

In humans, it is one of the most common parasites.[3] Blood test show that up to a third of the world population has been or is infected with T. gondii. Infection rates differ greatly from country to country.[4]

Although mild, flu-like symptoms occasionally occur during the first few weeks, infection with T. gondii generally produces no symptoms in healthy human adults.[5] But in infants, HIV/AIDS patients, and others with weakened immunity, infection can cause serious and occasionally fatal illness (toxoplasmosis).[5][2]p77

Infection in humans and other warm-blooded animals can occur

  1. by eating raw or undercooked meat containing T. gondii tissue cysts.[6][7]
  2. by drinking water or eating anything contaminated with oocysts.[8] in the faeces of an infected animal.[7]
  3. from a blood transfusion or organ transplant
  4. or by transmission from mother to foetus across the placenta.[7]

The parasite can only sexually reproduce in the intestines of members of the cat family (felids).[9] Felids are therefore the definitive hosts of T. gondii, with all other hosts defined as 'intermediate hosts'.

References[change | edit source]

  1. Weiss, Louis M. & Kami Kim, eds. 2011. Toxoplasma gondii: the model Apicomplexan: perspectives and methods. Academic Press/Elsevier, London, p49.
  2. 2.0 2.1 Dubey J.P. 2010. Toxoplasmosis of animals and humans. 2nd ed, CRC Press. ISBN 978-1-4200-9237-0
  3. "CDC – About Parasites". http://www.cdc.gov/parasites/about.html. Retrieved 12 March 2013.
  4. Pappas, G; Roussos N & Falagas M.E (2009). "Toxoplasmosis snapshots: global status of Toxoplasma gondii seroprevalence and implications for pregnancy and congenital toxoplasmosis.". International Journal for Parasitology 39 (12): 1385–94. doi:10.1016/j.ijpara.2009.04.003. PMID 19433092.
  5. 5.0 5.1 "CDC Parasites – Toxoplasmosis (Toxoplasma infection) – Disease". http://www.cdc.gov/parasites/toxoplasmosis/disease.html. Retrieved 12 March 2013.
  6. Tissue cyst = group of cells with a hard shell around them
  7. 7.0 7.1 7.2 Tenter, A.M; Heckeroth A.R. & Weiss L.M (2000). "Toxoplasma gondii: from animals to humans". International Journal for Parasitology 30 (12–13): 1217–58. doi:10.1016/S0020-7519(00)00124-7. PMC 3109627. PMID 11113252.
  8. Oocyst: a hardy, thick-walled spore able to survive for long periods outside a host. The zygote develops within the spore, which acts to protect it during transfer to new hosts. This method is found in some Apicomplexa.
  9. Dubey, JP (2009). "History of the discovery of the life cycle of Toxoplasma gondii". International Journal for Parasitology 39 (8): 877-882. doi:10.1016/j.ijpara.2009.01.005. PMID 19630138.