Toxoplasmosis is a disease caused by the parasite Toxoplasma gondii, primarily affecting the blood and lymphatic system, and is commonly transmitted through undercooked meats or contact with cat feces. The infection can lead to severe congenital issues in fetuses and poses risks, especially to immunocompromised individuals. Treatment options vary based on the patient's immune status, and preventive measures include avoiding cat feces and ensuring proper food hygiene.

1. Presented by
S.Hemapriya
II-M.Sc.,Applied Microbiology
K.M.G College Of Arts and Science

3. TOXOPLASMOSIS
 A disease of the blood and lymphatic system.
 Cats are a critical part of the life cycle.
 It is usually acquired by eating undercooked
meats but can also be acquired by contact with
cat feces.
 Primary problem is a congenital infection of
fetus, resulting in either stillbirth or a child with
severe brain damage or vision problems.

4. TOXOPLASMA GONDII
 Toxoplasmosis infection is caused by a parasite
called Toxoplasma gondii.
 Toxoplasma gondii was first discovered in
1908.
 Toxoplasma gondii is an intracellular parasite
in intestinal epithelium and muscle.
 Infects most species of warm-blooded animals,
including humans.

5. MORPHOLOGY
 Toxoplasma gondii occurs in three forms:
Trophozoite
Tissue cyst
Oocyst

6. TROPHOZOITE
 The trophozoite is crescent shaped, with one
end pointed and the other end rounded.
 It measures 3-7 µm in length.The nucleus is
ovoid and is situated at the blunt end of the
parasite.
 Electron microscopy reveals as apical complex
at the pointed end.
 The trophozoite stains well Giemsa stain, the
cytoplasm appearing azure blue and the nucleus
red.

7. TROPHOZOITE OF T.GONDII

8. TISSUE CYST
 Tissue cyst are the resting form of the parasite.
 They are found during chronic stage of the
infection and can be found in the brain(most
common site),skeletal muscles and various
other organs.
 The cyst wall is eosinophilic and stains with
silver,in contrast to the pseudocyst.
 With periodic acid-Schiff(PAS) stain,the cyst
wall stains weakly,and the parasites inside are
stained deeply.The slowly multiplying parasites
within the cyst are called Bradizoites.

9. TISSUE CYST OF T.GONDII

10. OOCYST
 Oocysts develop only in definitive hosts in the
intestine of cats and other felines but not in
humans.
 It is oval in shape and measures 10-12 µm in
diameter.Each cyst is surrounded by a thick
resistant wall.
 The oocysts are formed by sexual reproduction
(gametogony).
 When the infective oocyst is ingested,it releases
sporozoites in the intestine,which initiates
infection.

11. OOCYST OF T.GONDII

12. LIFE CYCLE OF T.GONDII

13. PATHOGENICITY AND
CLINICAL FEATURES
 The outcome of Toxoplasma infection depends
on the immune status of the infected person.
 Active progression of infection is more likely in
immunocompromised individuals.
Toxoplasmosis has acquired great importance
as one of the major fatal complication in
Acquired Immunodeficiency Syndrome
(AIDS).
 Most human infections are asymptomatic.
 Clinical toxoplasmosis may be congenital or
required.

14. LABORATORY DIAGNOSIS OF
T.GONDII

15. TREATMENT
 CONGENITAL TOXOPLASMOSIS:
 Neonates with congenital infection are treated
with oral Pyrimethamine (1 mgkg) daily and
Sulfadiazine (100 mgkg) with folinic acid for 1
year.
 Systemic corticosteroid may be added to reduce
chorioretinitis.

16. TREATMENT
 IMMUNOCOMPETENT PATIENTS:
 Patients with ocular toxoplasmosis are treated
for 1 month with Pyrimethamine plus either
Sulfadiazine or Clindamycin (600 mg QID).
 Folinic acid should be administered
concomitantly to avoid marrow suppressive
effect of Pyrimethamine.

17. TREATMENT
 IMMUNOCOMPROMISED PATIENTS:
 Trimethoprim-Sulfamethoxazole is the drug of
choice.If Trimethoprim-Sulfamethoxazole
cannot be tolerated by patients,Dapsone-
Pyrimethamine is the recommended alternative
drug of choice.
 Prophylaxis against Toxoplasma encephalitis
should be discontinued in patients who have
responded to Anti Retroviral Therapy (ART)
and whose CD4+ T-lymphocyte count has been
above 200µL for 3 months.

18. PROPHYLAXIS
 Individuals at risk,particularly pregnant
women,children and immunocompromised
persons should avoid contact with cat and its
feces.
 Proper cooking of meal.
 Proper washing of hands and washing of
vegetables and fruits before eating.
 Blood or blood products from seropositive
persons should not be given and screening for
T.gondii antibody should be done in all blood
banks.

19. CONTROL
 It is difficult to control toxoplasmosis because
of wide range of animal
reservoirs.Currently,there is no effective
vaccine available for humans.A genetically
engineered vaccine is under development for
use in cats.