د.حنان

LAB -7-

Toxoplasma gondii

• Worldwide.

• Zoonotic parasite; Toxoplasma is an opportunistic pathogen.
• Infects animals,cattle,birds,rodents,pigs, sheep and humans.
• Cause the disease: Toxoplasmosis,congential toxoplasmosis and cerebral toxoplasomsis.
• Intracellular parasite.

Morphology

• Toxoplasma gondii exists in three morphological forms, all parasite stages are infectious:
• Oocyst.
• Tachyzoites.
• Bradyzoites.(tissue cysts).


Oocyst
Round to slightly oval.
10 to 15 Mm long by 8 to 12 Mm wide.
The transparent oocyst contain two sporocysts,each with 4 sporozoites.
Surrounded by a clear,colorless,two-layered cell wall.

Tachyzoites

Bradyzoites

Toxoplasma gondii exists in three forms All parasite stages are infectious.

Oocysts

•

Bradyzoites

• TISSUE CYSTS
1. TACHYZOITES
2. TISSUE CYSTS
((BRADYZOIT
4. OOCYSTS

Tachyzoites

Life cycle



Life Cycle

Tissue phase (intermediate hosts).

Intermediate host gets infected by ingesting sporulated oocysts.
Oocytes do not become infectious until they sporulate, sporulation occurs
1- 5 days after that the oocyte is excreted in the feces.
Intermediate host
• Human, cattle, birds, rodents, pigs, and sheep.

Cat’s intestinal enterocytes

Bradyzoites infect cells and become trophozoites.
Cats Ingest of asexual stage tachyzoites & bradyzoites

Multiplication

Merozoites


Gametocytes

Zygote

Oocyst
Encapsulation of zygote within a rigid wall

The infective stage is the mature oocyst,tachyzoites(trophozoites),bradyzoites.

The diagnostic stage is the tachyzoites,encysted bradyzoites.
The intermediate host is the mammals,birds.
The final (definitive) host is the cat.

Modes of transmission

1_Direct contact with cat feces.
2_ingestion of undercooked meat & contaminated vegetables and drinks.
3_Transplacental.
4_Blood transfusion.


Lab Diagnosis of Toxoplasmosis
Serological test: both IgM and IgG levels may be determined using the indirect fluorescent antibody (IFA) test.
IgM antibodies by double-sandwich ELISA method.
IgG antibodies by indirect hem agglutination (IHA) test and ELISA.

Microscopic examination of the infected tissue.

Animal inoculation.
PCR.

Prevention and Control

• Avoidance of contact with cat feces.
• Avoidance of ingesting contaminated meat.
• Good cooking of the meat.
• Hand washing and wear a gloves when handling a cat.