Toxoplasma Flashcards
What is the superphylum of toxoplasma?
Alveolata
Cortical alveoli or inner membrane complex.
It is a flattened membranous cristernae underlying the plasma membrane
Alveolata
mitochondria with tubular christae
alveolata
Many are photosynthetic. It has a transverse flagellum that encircles th body and a longitudinal flagellum oriented perpendicular
Dinoflagellata
some or all of the surface is covered with short, dense hairlike structures (cilia) which beat to propel the ciliate through the water and/or to draw in food particles
ciliata
Diverse group. All parasitic.
Elements of the Apical
complex
Apicomplexa
an assemblage of cytoskeletal elements and secretory organelles No flagella or cilia except for the microgamete (sperm) All members of the phylum are parasitic
Apical Complex
Reproduction: Apicomplexa
both asexual and sexual
parasites of invertebrates,
some quite big (used as early research
models), Cryptosporidium might belong into
this category
Gregarines
small
parasites of blood cells which are
transmitted by arthropods
Haemosporidians (Plasmodium) and
Piroplasms (Babesia & Theileria
tissue parasites of vertebrates
and invertebrates (can have single (e.g.
Eimeria) or two hosts (e.g. Toxoplasma).
Coccidians
Initially found in 1908 as a tissue parasite of gondi (an african rodent)
Toxoplasma gondii
High prevalence in Europe. In the
US approx. 20-50% of the population is infected
Toxoplasma gondii
Transmission by tissue cysts (containing bradyzoites) or the oocyst
(containing sporozoites)
• Infection through ingestion of undercooked or raw
meat or contaminated water
Toxoplasma gondii
Parasite form
Tacgyzoites Bradyzoites Tissue Cysts Oocysts "TBTO" Throw back Thursday only!
rapidly growing meront or zoite observed in the early
stage of of infection
Tachyzoites
Slow-growing zoite or meront inside the tissue cysts
Bradyzoites
Found in the tissues, contain bradyzoites. Infective form
tissue cyst
Zygote forn and highly resistant form. This is also an infective form:
sporocyst or sporozoites
Oocysts
Life cycle of toxoplasma gondii
Ingestion of TG by car
Oocysts are produced and excreted in the feces.
Sporulation results in the formation of sporozoites
sporulated oocyst remain infective for months
intermediate host gets contact with the cyst.
How do they multiply?
endodiogeny
What are the sources of infection for toxoplasma?
Contaminated water or food Undercooked meat Mother to fetus Organ transplant (rare) Blood transfusion (rare)
The acute infection is carried by which stage?
Tachyzoite stage
These divide rapidly and aggressively destroy tissues. These can also cross the blood brain barrier and the placenta.
Crescent shaped
• 2 by 6 μm
• Asexual form
• Multiplies by endodyogeny
• It can infect phagocytic and nonphagocytic,
nucleated cells.
Tachyzoites
Are resistant to all currently available drugs
Bradyzoites
Bradyzoite cysts are highly infective if
INGESTED
This mark the beginning of the chronic phase
bradyzoite stage
are resistant to low pH and digestive enzymes durinfg stomach passage
bradyzoites
Three situations can lead to severe diseases
1) congenital toxoplasmosis
2) occular toxoplasmosis in immunocompetent adults
3) loss of a functional immune system
acute infection of the expectant mother.
Severity depends on the stage of pregnancy.
Spontaneous abortions or neurological disorders such as
blindness and mental retardation can result.
Congenital disease
Pregnancy and toxoplasmosis
If a women is infected for the first
time during pregnancy the parasite
can transverse the placenta and
cause fetal disease
Only 25-30% of seropositive patients who develop AIDS develop TE
• Involvement of the CNS.
• Symptoms: lethargy, loss of memory to severe dementia, focal to major
motor seizures
Toxoplasmic encephalitis
What happens to the eye if it gets infected by the parasite toxoplasma?
ocular toxoplasmosis
Diagnosis of toxoplasmosis
Parasites can be detected in biopsied specimens or cerebral spinal fluid.
Not very reliable.
T or F: As all apicomplexa T. gondii only
replicates within cells
True
T or F: The oocyst is noninfectious before sporulation.
• Unsporulated oocysts are subspherical to spherical and are 10 by 12
μm in diameter.
True
Oocysts has two _______ ________
ellipsoidal sporocysts
Prevention of tocoplasmosis
Avoid raw or undercooked meat. (Cooking kills Toxoplasma)
• Wash raw fruits and vegetables well before eating.
• Remove feces from the litter box every day, to eliminate any parasites before oocysts sporulate
• Keep cats indoors to prevent hunting. Cats can become infected by eating infected rodents or birds.
• Feed cats only commercial food or well-cooked meat.
• Do not feed cats raw or undercooked meat.
• Do not adopt cats who have lived outdoors or who have been fed raw meat.
• Do not handle stray cats.
