Lecture 06 - Toxoplasma Flashcards
What is toxoplasma
a protozoan parasite in the phylum apicomplexa that infects most warm-blooded animals
Where do toxoplasma sexually replicate
cats
What is unique about toxoplasma
it can invade the host cells and evade the immune system
What is a trophozoite
does the invading
has two generations (tachyzoites and bradyzoites)
What are tachyzoites
fast multiplying
What are bradyzoites
slow multiplying or inert
How do trophozoites multiply
asexual multiplication via internal budding
What are cysts
the resting/chronic form, has a thick wall to protect it
What is a pseudocyst
when mother cell bursts it stays connected for a short period and looks like a cyst
Where is the intestinal form found
cats
What is the pathogensis of toxoplasma
an intracellular parasite that only invade nucleated cells, cell invasion is facilitated by the apical complex and survival is ensured by the creation of a protective parasitophorous vacuole
What is the acute phase of infection
tachyzoites invading cells, cell destruction, mononuclear cell inflammation, blood vessel blockage
What is the chronic phase of infection
bradyzoites and tissue cysts, latency/immunological evasion, hyopersensiticity
How do they evade the immune system
the walls of tissue cysts are made of the host so not recognize as intruder
Sites of invastion
lymph nodes, cardiac or skeletal muscle, brain, eyes
What is dangerous about pregnant women
if they are infected for the first time during pregnancy toxoplasma can cross the placenta and cause abortion or congenital defects
What happens with toxoplasma and the brain
it infects neurons directly by increasing dopamine synthesis causing a modification of host behaviour
What is the association with toxoplasma and human abnormalities
association with increased aggression in women, increase impulsivity in men, homicide rates, suicide rates, schizophrenia
Acute disease symptoms
90% asympotomatic
lymphadenopathy
mono like
hepatitis with jaundice
splenomegaly
rash
involvement of CNS an eye (often seen in reactivation)
Chronic disease symptoms
always asymptomatic
What is ocular toxoplasmosis
when infection gets into the eye and causes hemorrhage or scarring
What can transplacental transmission cause
abortion or stillbirth, CNS lesions, blindness, hydrocephaly, cerebral calcifications
What is the transmission of toxoplasma
ingestion, transfusion or transplantation, transplacentally, reactivation of chronic infection
What is the direct demonstration of toxoplasma
giemsa stain
fluorescent antibody stains
NAAT
animal inoculation/tissue cultures (rarely used)
What is the serology of toxoplasma
sabin feldman dye test
immunofluorescent assays
enzyme immunoassays
