Toxoplasma Gondii

Question 1

Toxoplasma Gondii is an obligate intracellular parasite. Explain

Answer 1

It can only replicaqte and survive inside the cell

Question 2

Who is the definitive host?

Answer 2

Cat

Question 3

Who is the accidental host?

Answer 3

• Mammals, including man
• Avian (birds species)
• Cold-blooded vertebrates

Question 4

What is the mode of infection?

Answer 4

i) faecal-oral = Eating contaminated food (oocyst containing sporozoite)
ii) ingest cyst (containing bradyzoite) embedded in undercook meat
iii) transplacental, organ transplant, blood transfusion. (tachyzoite)

Question 5

What is the type of reproduction in man host?

Answer 5

asexually by endodyogeny

Question 6

What is the type of reproduction in cat host?

Answer 6

sexually. oocyst release sporozoite

Question 7

What is the habitat for toxoplasma Gondii in definitive host?

Answer 7

Columnar epithelial cells of small intestine

Question 8

What is the habitat for toxoplasma Gondii in accidental host?

Answer 8

• columnar epithelial cells of small intestine
• develop in vacoules in any nucleated cells (macrophage)

Question 9

Could it affect other sites or organs ? If yes, list some.

Answer 9

Yes. Brain, Liver, Muscle, Retinal cells, Lymph node, Spleen

Question 10

Infective form in contaminated food & drinks is

Answer 10

Oocyst with sporozoite

Question 11

Infective form in blood t’fusion & transplacental is

Answer 11

Tachyzoite

Question 12

Infective form in cyst in undercooked meat is

Answer 12

Bradyzoite

Question 13

Both sporozoite and bradyzoite will become ____________

Answer 13

tachyzoite

Question 14

Tachyzoite is in infective and invasive form can cause acute or chronic infection?

Answer 14

acute infection

Question 15

Bradyzoite is in an infective form can cause acute or chronic infection?

Answer 15

Chronic infection

Question 16

Many tachyzoites in a host cell vacuole and mononuclear cells develop parasite membrane forming a cyst. Encysted stage the parasite is known as ___________

Answer 16

bradyzoite

Question 17

What is the morphology of the trachyzoite ?

Answer 17

• Pyriform shape
• It has membrane, nucleus and various organelle.

Question 18

Can Bradyzoite in cyst remains viable for years?

Answer 18

Yes

Question 19

How much sporocyst in one oocyst?

Answer 19

2 sporocyst in 1 oocyst

Question 20

How much sporozoites in one sporocyst?

Answer 20

4 sporozoites in one sporocyst.

notes: 1 oocyst has 2 sporocyst. Each sporocyst has 4 sporozoites.

Question 21

During transplantation, what form of toxoplasma gondii will infect the man?

Answer 21

Bradyzoite

Question 22

For blood transfusion, where can tachyzoite be found?

Answer 22

It can be found within white blood cells, platelets and contaminated packed red blood cells.

Question 23

In the human host, does the parasites form tissue cysts most commonly in skeletal muscle, myocardium, brain, and eyes?

Answer 23

Yes

Question 24

Explain the life cycle of Toxoplasma Gondii in human.

Answer 24

• Tissue with infected cyst enters human body.
• The cyst wall is digested releasing the bradyzoite maturing
becoming tachyzoite in lumen of small intestine.
• Tachyzoites penetrate the epithelial cells in small
intestine.
• Endodyogeny (asexual) cycle takes place.
• Tachyzoite enters circulation via lymphatic or haematogenous spread.
• Tachyzoites resides in muscle or neural tissue.
• Tacyzoites forms cysts with bradyzoites in tissue.

Question 25

Explain the life cycle of Toxoplasma Gondii in cat.

Answer 25

• Cat eats mice, rats, rodents and/or raw meat containing the infective cyst. • The cyst wall is digested releasing the bradyzoite maturing becoming tachyzoite in lumen of small intestine. • Tachyzoites penetrate the epithelial cells in small intestine. • Asexual & sexual cycle takes place. • Sexual (gametogony) cycle and oocyst formation. • Oocyst contains undifferentiated material, develop into 2 sporocyst within several days. • Each sporocyst contains 4 sporozoites.

Question 26

What happen during acute infection of Toxoplasma Gondii?

Answer 26

- Tachyzoites divide repeatedly by endodyogony (asexual). - Host cells will swell up and rupture releasing tachyzoite. - Develop a membrane and become a cyst or pseudocyst.

Question 27

What happen during chronic infection of Toxoplasmosis?

Answer 27

Bradyzoites - cysts within tissue with tough wall - in the Brain, liver, heart, & muscles - Persist for months or years. - While bradyzoites are dormant, they can stimulate the host's immune system to maintain a state of immunity against T. Gondii - This allow the parasite to evade the host's immune response and cause chronic infection. -When immune response become compromised, the bradyzoite can reactivate and transform into rapidly dividing tachyzoite.

Question 28

Does Intestinal infection cause asymptomatic or symptomatic?

Answer 28

Intestinal infection cause asymptomatic

Question 29

If it infect extra-intestinal sites what are the symptoms for children, adults, AIDS patient and immunsuppressed patients?

Answer 29

1. Acute form in children and adults that resembles typhus & is usually fatal. 2. Resembles infectious mononucleosis. 3. In immunocompromised AIDS patients can present with meningio-encephalitis. 4. In immunosuppressed patients present with pneumonitis, lymphadenopathy, myocarditis and encephalopathy.

Question 30

Chronic infection of Toxoplasmosis in adults can present with:

Answer 30

1. Chorioretinitis. 2. Lymphadenopathy usually single, post-cervical.

Question 31

For the Congenital Toxoplamosis, what is the symptoms, and List the outcomes of pregnancy for 1st, 2nd and 3rd trimester if the mother gets infected.

Answer 31

Mother is asymptomatic. 1st trimester- miscarriage 2nd trimester- miscarriage or still born 3rd trimester- congenital infection

Question 32

What are the typical syndrome of the congenital infected baby?

Answer 32

Intra-cerebral calcification. Chorioretinitis. Hydrocephalus.

Question 33

Diagnosis for Toxoplasma Gondii has two methods

Answer 33

Direct method Indirect method

Question 34

Explain the direct method to diagnose Toxoplasma Gondii. Suggest ways to detect the parasite

Answer 34

Tissues or fluids suspected of containing parasites taken: - Blood serology - Biopsy lymph node or muscle - CSF Detection of parasites by: 1. Staining by Giemsa or immunoflorescence 2. Tissue culture

Question 35

How to diagnose for Toxoplasma Gondii using indirect method?

Answer 35

It measures the immune response. It detects the presence of IgG and IgM Toxoplasma specific anribodies via Serologic diagnosis.

Question 36

How to diagnose for Toxoplasma Gondii using indirect method for pregnant ladies?

Answer 36

IgG avidity test can be carried out to determine the time of infection for pregnant ladies.

Question 37

How to diagnose for Toxoplasma Gondii using indirect method for congenital infection?

Answer 37

By the demonstration of IgM (not IgG)

Question 38

What are the treatment for immunocompetent people?

Answer 38

i. no treatment given ii. If ocular – Pyrimethamine

Question 39

What is the treatment for immunocompromised people?

Answer 39

Pyrimethamine – as prophylaxis and treatment

Question 40

What is the treatment for congenital Toxoplasmosis?

Answer 40

Pyrimethamine

Question 41

What are the treatment for pregnant woman?

Answer 41

Spiramycin (<18/40) Pyrimethamine (>18/40)

Question 42

NOTES

Answer 42

Clinical presentation for Toxoplasmosis can be asymptomatic, symptomatic and congenital.

Question 43

For AIDS patient, is it possible to perform serology or PCR of parasite DNA?

Answer 43

No. Because AIDS patient has reduced antibody production