toxoplasmosis is a disease caused by toxoplasma gondii parasite.. in this slides we can learn about their morphology, lifecycle, clinical features , laboratory diagnosis, treatment, prophylaxis, control.

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.