BIO220H1 Lecture Notes - Lecture 18: Toxoplasma Gondii, Microorganism, Fetus
Lecture 18 reading
“How Your Cat Is Making You Crazy”
-Jaroslav Flegr
-Starting in the early 1990s, he began to suspect that a single-celled parasite in the protozoan
family was subtly manipulating his personality, causing him to behave in strange, often self-
destructive ways.
-The parasite, which is excreted by cats in their feces, is called Toxoplasma gondii (T. gondii or
Toxo for short) and is the microbe that causes toxoplasmosis
-woman who becomes infected during pregnancy can transmit the disease to the fetus, in
some cases resulting in severe brain damage or death. T. gondii is also a major threat to
people with weakened immunity.
-the “latent” parasite may be quietly tweaking the connections between our neurons, changing
our response to frightening situations, our trust in others, how outgoing we are, and even our
preference for certain scents. that the organism can also contribute to car crashes, suicides,
and mental disorders such as schizophrenia
-T. gondii, can turn a rat’s strong innate aversion to cats into an attraction, luring it into the
jaws of its No. 1 predator.
-the organism rewires circuits in parts of the brain that deal with such primal emotions as fear,
anxiety, and sexual arousal.
• Wasps lay eggs inside ladybugs by inserting eggs into the underside of the
ladybug; the larva feed on the fluid of the ladybug's body cavity when the eggs
hatch !
• Larva exits ladybug when it grows big enough, and forms cocoon beneath
ladybug, which is immobilized !
• Ladybug scares off any predators of the larva; does this for a week until an adult
wasp emerges from the cocoon; ladybug dies !
• Wasp injects chemicals into the ladybug, as well as a virus that replicates in the
wasp's ovaries which immobilizes the ladybug !
• When killfish are infected with flatworms, they spend more time near the surface
(which they don't normally do) and get eaten by birds; flatworm reproduces in
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BIO220H1 Full Course Notes
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