Toxoplasma gondii is an obligate intracellular parasite that causes toxoplasmosis, with transmission routes including consumption of undercooked meat and congenital transmission during pregnancy. The life cycle involves three stages: tachyzoites, bradyzoites, and sporozoites, with various diagnostic techniques such as microscopy and serology used for detection. Treatment options for congenital cases include spiramycin for mothers and pyrimethamine with sulfadiazine for affected fetuses, alongside prevention strategies like proper food handling and hygiene.

1. TOXOPLASMA GONDII
TOXON : arc , bow
PLASMA: shape , form

2. Toxoplasma gondii is an obligate
intracellular, parasitic alveolate that
the disease toxoplasmosis.
Scientific name: Toxoplasma gondii
Class: Conoidasida
Genus: Toxoplasma
Domain: Eukaryota
Phylum: Apicomplexa
Family: Sarcocystidae

3.  IN 1908
CHARLES NICOLLE AND LOUIS MANCEAUX
 initially believed the
organism to be a member of
the genus Leishmania that
they described as
“Leishmania gondii”.

4. STRUCTURE

5. MORPHOLOGY:
Three morphological forms

6. LIFE CYCLE:
The three stages of T. gondii
(i) Tachyzoites (trophozoites): rapidly proliferate and destroy
infected cells during acute infection.
(ii) Bradyzoites: slowly multiply in tissue cysts.
(iii) Sporozoites in oocysts.
Cats become infected with T. gondii by carnivorism or by ingestion of
oocysts

7. LIFE CYCLE

8. PATHOGENESIS AND EPIDEMIOLOGY:
Human infection may be acquired in several ways:
• Ingestion of undercooked infected meat containing T.
gondii cysts
• Ingestion of the oocyst from fecaly contaminated hands,
food, or water.
• Organ transplantation or blood transfusion
• Transplacental transmission
• Accidental inoculation of tachyzoites
The two major routes of transmission to humans are oral and
congenital.

9. CONGENITAL
TOXOPLASMOSIS
Congenital toxoplasmosis
results from an acute primary
infection accquired by the
mother during pregnancy.
OCULAR
TOXOPLASMOSIS
Ocular toxoplasmosis, an
important cause of Chorioretinitis
in the United States, may be the
result of congenital or acquired
infection.

10. DIAGNOSIS
 Direct microscopy  Detection of tachyzoites in
blood and tissue cyst in tissue biopsy
 Staining methods:
1. Giemsa
2. PAS
3. Silver stains
4. Immunoperoxidase stain

11. SEROLOGY:
• Detection of Toxoplasma antigen by ELISA
• Detection of Toxoplasma antibody by
1. Sabin-Feldman dye test
2. IgM ELISA
3. IgG ELISA
4. IgG avidity test

12. SABIN-FELDMAN DYE TEST:
• Complement mediated neutralization test that requires live tachyzoites.
• Live tachyzoites are incubated with complement and test serum.
• Alkaline methylene blue dye is added and reincubated.
• Toxoplasma antibodies in the serum bind to the antigens in the live
tachyzoites  killed due to complement mediated lysis
• Killed tachyzoites  thin, distorted and colourless
• The dilution of the test serum at which 50% of the tachyzoites are killed 
antibody titer of the test serum

13. DIAGNOSIS OF T.GONDII
• Toxoplasma antigens in amniotic fluid
• PCR
• IgM antibodies in fetal blood by ELISA
• Ultrasound of fetus at 20 to 24 weeks of gestation

14. TREATMENT
Congenital toxoplasmosis:
• Spiramycin can treat infection in the pregnant mother.
• Pyrimethamine and sulfadiazine can treat fetal infection (diagnosed during
the pregnancy).
• Sulfadiazine plus pyrimethamine with folinic acid.
Also given steroids. (to infants)

15. PREVENTION
 Consumption of cooked meat
 Hand hygiene
 Prenatal and antenatal screening to detect Toxoplasma
infection in women of child bearing age
 Proper handling of pet cats
 Screening of blood donors and organ donors

16. THANKYOU