Toxoplasma Gondii Flashcards
Toxoplasma Gondii is an obligate intracellular parasite. Explain
It can only replicaqte and survive inside the cell
Who is the definitive host?
Cat
Who is the accidental host?
- Mammals, including man
- Avian (birds species)
- Cold-blooded vertebrates
What is the mode of infection?
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)
What is the type of reproduction in man host?
asexually by endodyogeny
What is the type of reproduction in cat host?
sexually. oocyst release sporozoite
What is the habitat for toxoplasma Gondii in definitive host?
Columnar epithelial cells of small intestine
What is the habitat for toxoplasma Gondii in accidental host?
- columnar epithelial cells of small intestine
- develop in vacoules in any nucleated cells (macrophage)
Could it affect other sites or organs ? If yes, list some.
Yes. Brain, Liver, Muscle, Retinal cells, Lymph node, Spleen
Infective form in contaminated food & drinks is
Oocyst with sporozoite
Infective form in blood t’fusion & transplacental is
Tachyzoite
Infective form in cyst in undercooked meat is
Bradyzoite
Both sporozoite and bradyzoite will become ____________
tachyzoite
Tachyzoite is in infective and invasive form can cause acute or chronic infection?
acute infection
Bradyzoite is in an infective form can cause acute or chronic infection?
Chronic infection
Many tachyzoites in a host cell vacuole and mononuclear cells develop parasite membrane forming a cyst. Encysted stage the parasite is known as ___________
bradyzoite
What is the morphology of the trachyzoite ?
- Pyriform shape
- It has membrane, nucleus and various organelle.
Can Bradyzoite in cyst remains viable for years?
Yes
How much sporocyst in one oocyst?
2 sporocyst in 1 oocyst
How much sporozoites in one sporocyst?
4 sporozoites in one sporocyst.
notes: 1 oocyst has 2 sporocyst. Each sporocyst has 4 sporozoites.
During transplantation, what form of toxoplasma gondii will infect the man?
Bradyzoite
For blood transfusion, where can tachyzoite be found?
It can be found within white blood cells, platelets and contaminated packed red blood cells.
In the human host, does the parasites form tissue cysts most commonly in skeletal muscle, myocardium, brain, and eyes?
Yes
Explain the life cycle of Toxoplasma Gondii in human.
• 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.
Explain the life cycle of Toxoplasma Gondii in cat.
• 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.
What happen during acute infection of Toxoplasma Gondii?
- Tachyzoites divide repeatedly by endodyogony (asexual).
- Host cells will swell up and rupture releasing tachyzoite.
- Develop a membrane and become a cyst or pseudocyst.
What happen during chronic infection of Toxoplasmosis?
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.
Does Intestinal infection cause asymptomatic or symptomatic?
Intestinal infection cause asymptomatic
If it infect extra-intestinal sites what are the symptoms for children, adults, AIDS patient and immunsuppressed patients?
- Acute form in children and adults that resembles typhus & is usually fatal.
- Resembles infectious mononucleosis.
- In immunocompromised AIDS patients can present with
meningio-encephalitis. - In immunosuppressed patients present with pneumonitis,
lymphadenopathy, myocarditis and encephalopathy.
Chronic infection of Toxoplasmosis in adults can present with:
- Chorioretinitis.
- Lymphadenopathy usually single, post-cervical.
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.
Mother is asymptomatic.
1st trimester- miscarriage
2nd trimester- miscarriage or still born
3rd trimester- congenital infection
What are the typical syndrome of the congenital infected baby?
Intra-cerebral calcification. Chorioretinitis. Hydrocephalus.
Diagnosis for Toxoplasma Gondii has two methods
Direct method
Indirect method
Explain the direct method to diagnose Toxoplasma Gondii. Suggest ways to detect the parasite
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
How to diagnose for Toxoplasma Gondii using indirect method?
It measures the immune response.
It detects the presence of IgG and IgM Toxoplasma specific anribodies via Serologic diagnosis.
How to diagnose for Toxoplasma Gondii using indirect method for pregnant ladies?
IgG avidity test can be carried out to determine the time of infection for pregnant ladies.
How to diagnose for Toxoplasma Gondii using indirect method for congenital infection?
By the demonstration of IgM (not IgG)
What are the treatment for immunocompetent people?
i. no treatment given
ii. If ocular – Pyrimethamine
What is the treatment for immunocompromised people?
Pyrimethamine – as prophylaxis and treatment
What is the treatment for congenital Toxoplasmosis?
Pyrimethamine
What are the treatment for pregnant woman?
Spiramycin (<18/40)
Pyrimethamine (>18/40)
NOTES
Clinical presentation for Toxoplasmosis can be asymptomatic, symptomatic and congenital.
For AIDS patient, is it possible to perform serology or PCR of parasite DNA?
No. Because AIDS patient has reduced antibody production
