Toxoplasma gondii
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Epidemiology
- obligate intracellular parasite with worldwide distribution in hosts: human; domestic & wild birds & mammals, especially carnivores
- the sexual stage in the life cycle occurs within intestinal epithelium of felines (cats) which are exclusive & definitive hosts
- sexual & sexual reproduction (schizogony & gametogony) lead to development of immature oocysts which are passed in the feces
- maturation into infective oocysts containing 2 sporocysts each with 4 sporozoites occurs over 2-21 days
- ingestion of infective oocysts in susceptible hosts leads to disruption of cysts with release of sporozoites which then transform into tachyzoites (trophozoites)
- tachyzoites may infect any nucleated cell
- proliferation of tachyzoites leads to cell death & host injury during the acute phase of infection
- after immunity develops, cysts are formed in tissues which may contain thousands of slowly growing bradyzoites
- tissue cysts are characteristic of chronic infection
- all stages of the life cycle occur in felines, but only trophozoites occur in humans & other intermediate hosts
Laboratory
- Toxoplasma gondii antigen
- Toxoplasma gondii serology*
- Toxoplasma gondii in isolate
- Toxoplasma gondii DNA
- see Toxoplasmosis & ARUP consult[3]
* modest but significant association between Toxoplamsma gondii seropositivity & impaired performance on cognitive testing in all domains analyze (processing speed, working memory, short-term verbal memory, executive function) in healthy adults average age ~ 50 years
* association between Toxoplasma gondii IgG ELISA serointensity & frailty[6]
Comparative biology
- wolves infected with Toxoplasma gondii are 46 times more likely to become pack leaders & 11 times more likely to start a new pack than uninfected animals[5]
More general terms
Additional terms
References
- ↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1268-69
- ↑ Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1197-1201
- ↑ 3.0 3.1 ARUP Consult: Toxoplasma gondii The Physician's Guide to Laboratory Test Selection & Interpretation https://arupconsult.com/content/toxoplasma-gondii
- ↑ Swift Yasgur B Common Parasite Now Tied to Impaired Cognitive Function. Medscape - Jul 22, 2021. https://www.medscape.com/viewarticle/955248
de Haan L, Sutterland AL, Scotborgh JV et al Association of Toxoplasma gondii Seropositivity With Cognitive Function in Healthy People. A Systematic Review and Meta-analysis. JAMA Psychiatry. Published online July 14, 2021 PMID: https://www.ncbi.nlm.nih.gov/pubmed/34259822 PMCID: PMC8281022 (available on 2022-07-14) https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2781883 - ↑ 5.0 5.1 Marris E Parasite gives wolves what it takes to be pack leaders. Study is one of the few to show the behavioural effects of Toxoplasma gondii in wild animals. Nature News. Nov 24, 2022 https://www.nature.com/articles/d41586-022-03836-9
- ↑ 6.0 6.1 Mohyuddin H, Laffon B, Teixeira JP et al Toxoplasma gondii IgG Serointensity Is Positively Associated With Frailty. J Gerontol A Biol Sci Med Sci. 2023 Nov 6:glad228 PMID: https://www.ncbi.nlm.nih.gov/pubmed/37939652 https://academic.oup.com/biomedgerontology/advance-article/doi/10.1093/gerona/glad228/7334598