behavioral changes associated with toxoplasmosis infection , general review of toxoplasmosis infection

2. INTRODUCTION
Toxoplasma gondii is a species of parasitic
protozoa in the genus Toxoplasma
The definitive host of T. gondii is the cat
The parasite can be carried by many warm-
blooded animals (birds or mammals
The disease caused by it is called
toxoplasmosis

3. The life cycle of T. gondii has two
phases:
-sexual :
occur only in members of the Felidae
family (domestic and wild cats), which
considered as a primary host.
-Asexual:
can occur in any warm-blooded
animal, like other mammals and birds
In the intermediate hosts (as well the
definitive host) the parasite invades
cells, forming intracellular s vacuoles
containing bradyzoites ( the slowly
replicating form of the parasite).
Vacuoles formed mainly within the
muscles and brain.

4. Mode of transmission
undercooked meat of animals harboring tissue
cysts
consuming food or water contaminated with cat
feces
consuming food or water contaminated
environmental samples (such as fecal-
contaminated soil)
blood transfusion or organ transplantation .
transplacentally from mother to fetus

5. Behavioral changes
IN ANIMALS
Studies show that Infected rodents are:
more active, first to enter traps, less fearful of cats
and associated smells
Mechanism in brain : there is an elevation in
dopamine, which is known to alter novelty-seeking
and neuroticism (personality trait characterized
by instability, anxiety and aggression)

6. Behavioral changes
IN HUMAN
Recent epidemiologic studies indicate that
infectious agents may contribute to some cases
of schizophrenia(a pervasive neuropsychiatric
disease of uncertain cause that affects
approximately 1% of the adult population in the
U.S &Europe
Toxoplasmosis also altered mental status of
60% of patients & causing symptoms like :
delusions, auditory hallucinations, and thought
disorders

7. Behavioral changes
THE MECHANISIM by which the parasite produce
their effect include :
The parasite infects the brain by forming a cyst
within its cells
produces an enzyme called tyrosine hydroxylase,
which is needed to make dopamine.
Dopamine’s role in mood, sociability, attention,
motivation and sleep patterns
schizophrenia has long been associated with
dopamine level

8. CONGENITAL TOXOPLASMOSIS
• Toxoplasma is an important cause of abortions and stillbirths
after primary infection in pregnant women.
• The organism can also cross the placenta and infect the
fetus.
• The symptoms of congenital toxoplasmosis include:
- abnormal changes in head size (hydrocephaly or
microcephaly)
- Intracranial calcifications
- deafness
-seizures, cerebral palsy
- damage to the retina, and mental retardation.