Toxoplasma gondii

Pictures

Picture	Title	Caption	Copyright
Title Life cycle of Toxoplasma gondii Caption Diagrammatic representation of the Toxoplasma gondii life cycle. Copyright USDA	Life cycle of Toxoplasma gondii	Diagrammatic representation of the Toxoplasma gondii life cycle.	USDA
Title Stages of Toxoplasma gondii Caption (a) Unsporulated oocyst in fecal float of cat feces. Unstained. Note double layered oocyst wall (arrow) enclosing a central undivided mass. (b) Sporulated oocyst with a thin oocyst wall (large arrow), 2 sporocysts (arrowheads). Each sporocyst has 4 sporozoites (small arrow), which are not in complete focus. Unstained. Copyright USDA	Stages of Toxoplasma gondii	(a) Unsporulated oocyst in fecal float of cat feces. Unstained. Note double layered oocyst wall (arrow) enclosing a central undivided mass. (b) Sporulated oocyst with a thin oocyst wall (large arrow), 2 sporocysts (arrowheads). Each sporocyst has 4 sporozoites (small arrow), which are not in complete focus. Unstained.	USDA
Title Stages of Toxoplasma gondii Caption (a) Schizont (arrow) with several merozoites (arrowheads) separating from the main mass. Impression smear of infected cat intestine. Giemsa stain. (b) A male gamete with two flagella (arrows). Impression smear of infected cat intestine. Giemsa stain. Copyright USDA	Stages of Toxoplasma gondii	(a) Schizont (arrow) with several merozoites (arrowheads) separating from the main mass. Impression smear of infected cat intestine. Giemsa stain. (b) A male gamete with two flagella (arrows). Impression smear of infected cat intestine. Giemsa stain.	USDA
Title Stages of Toxoplasma gondii Caption (a) Tachyzoites in impression smear of lung. Note crescent-shaped individual tachyzoites (arrows), dividing tachyzoites (arrowheads) compared with size of host red blood cells and leukocytes. Giema stain. (b) Tissue cysts in section of muscle. The tissue cyst wall is very thin (arrow) and encloses many tiny bradyzoites (arrowheads). Hematoxylin and eosin stain. Copyright USDA	Stages of Toxoplasma gondii	(a) Tachyzoites in impression smear of lung. Note crescent-shaped individual tachyzoites (arrows), dividing tachyzoites (arrowheads) compared with size of host red blood cells and leukocytes. Giema stain. (b) Tissue cysts in section of muscle. The tissue cyst wall is very thin (arrow) and encloses many tiny bradyzoites (arrowheads). Hematoxylin and eosin stain.	USDA
Title Stages of Toxoplasma gondii Caption Tissue cyst separated from host tissue by homogenization of infected brain. Note tissue cyst wall (arrow) and hundreds of bradyzoites (arrowheads). Unstained. Copyright USDA	Stages of Toxoplasma gondii	Tissue cyst separated from host tissue by homogenization of infected brain. Note tissue cyst wall (arrow) and hundreds of bradyzoites (arrowheads). Unstained.	USDA

Identity

Preferred Scientific Name

• Toxoplasma gondii

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Protista
•         Phylum: Protozoa
•             Subphylum: Apicomplexa
•                 Order: Eucoccidiorida
•                     Family: Sarcocystidae
•                         Genus: Toxoplasma
•                             Species: Toxoplasma gondii

Diseases Table

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Pathogen Characteristics

The name Toxoplasma (toxon = arc, plasma = form) is derived from the crescent shape of the tachyzoite stage. There are 3 infectious stages of T. gondii: the tachyzoites (in groups), the bradyzoites (in tissue cysts), and the sporozoites (in oocysts).

The tachyzoite is often crescent-shaped and is approximately the size (2 x 6 µm) of a red blood cell. The anterior end of the tachyzoite is pointed, and the posterior end is rounded. It has a pellicle (outer covering), several organelles including subpellicular microtubules, mitochondria, smooth and rough endoplasmic reticulum, a Golgi apparatus, apicoplast, ribosomes, a micropore, and a well-defined nucleus. The nucleus is usually situated toward the central area of the cell.

Tissue cysts vary in size from 5-70 µm and remain intracellular. The tissue cyst wall is elastic, thin <0.5 µm), and may enclose hundreds of the crescent-shaped, slender T. gondii stage known as bradyzoites (Dubey et al., 1998). The bradyzoites are approximately 7 x 1.5 µm. Bradyzoites differ structurally only slightly from tachyzoites. They have a nucleus situated toward the posterior end whereas the nucleus in tachyzoites is more central. Bradyzoites are more slender than are tachyzoites and they are less susceptible to destruction by proteolytic enzymes than are tachyzoites.

In freshly passed faeces, oocysts are unsporulated (non-infective). Unsporulated oocysts are totally or nearly spherical and are 10 x 12 µm in diameter. They sporulate (become infectious) outside the cat within 1 to 5 days depending upon aeration and temperature. Sporulated oocysts contain two ellipsoidal sporocysts. Each sporocyst contains 4 sporozoites. The sporozoites are 2 x 6 to 8 µm in size.

Host Animals

Threatened Species

Risk and Impact Factors

• Pest and disease transmission
• Pathogenic

References

Dubey JP, Lindsay DS, Speer CA, 1998. Structures of Toxoplasma gondii tachyzoites, bradyzoites, and sporozoites and biology and development of tissue cysts. Clinical Microbiology Reviews, 11(2):267-299; 183 ref

National Marine Fisheries Service, 2007. Recovery Plan for the Hawaiian Monk Seal (Monachus schauinslandi). Second Revision. In: Recovery Plan for the Hawaiian Monk Seal (Monachus schauinslandi). Second Revision : National Marine Fisheries Service.165 pp.

OIE Handistatus, 2002. World Animal Health Publication and Handistatus II (dataset for 2001). Paris, France: Office International des Epizooties

OIE Handistatus, 2003. World Animal Health Publication and Handistatus II (dataset for 2002). Paris, France: Office International des Epizooties

OIE Handistatus, 2004. World Animal Health Publication and Handistatus II (data set for 2003). Paris, France: Office International des Epizooties

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (data set for 2004). Paris, France: Office International des Epizooties

US Fish and Wildlife Service, 2003. Final Revised Recovery Plan for the Southern Sea Otter (Enhydra lutris nereis). In: Final Revised Recovery Plan for the Southern Sea Otter (Enhydra lutris nereis) : US Fish and Wildlife Service.179 pp. http://ecos.fws.gov/docs/recovery_plan/030403.pdf

US Fish and Wildlife Service, 2013. Southwest Alaska Distinct Population Segment of the Northern Sea Otter (Enhydra lutris kenyoni) Recovery Plan. In: Southwest Alaska Distinct Population Segment of the Northern Sea Otter (Enhydra lutris kenyoni) Recovery Plan : US Fish and Wildlife Service.175 pp. http://ecos.fws.gov/docs/recovery_plan/Recovery%20Plan%20SW%20AK%20DPS%20Sea%20Otter%20Aug13.pdf

Distribution References

CABI Data Mining, 2001. CAB Abstracts Data Mining.,

CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (dataset for 2004)., Paris, France: Office International des Epizooties.

Distribution Maps