microimm parasitology cram

Giardia duodenalis

Monoxenous flagellated protozoan that causes pseudomembrane colitis.

Mech: Colonizes in small intestine and reproduces a lot (trophozoite form), then it converts to a cyst and conserves energy to survive. Cysts are ingested and each make 2 trophozoites which adhere to the intestinal epithelial cells. As the parasites move to the colon, trophozoites become cysts. They damage villi → less nutrient uptake

Transmission: fecal oral route

Plasmodium falciparum

diheteroxenous apicomplexan protozoan that causes malaria.

Mosquito life cycle: Mosquito is definitive host. With a blood meal, gametocytes are taken in and they mature into gametes upon moving to the stomach of mosquito. Microgamete will fertilize macrogamete to make a 2n zygote, which then duplicates to make 4n ookinete. This migrates through the stomach epithelial cells and grows on the outside. Massive asexual reproduction to make sporozoites which are a lot of haploids. These move to the salivary glands of the mosquito.

Human life cycle: Humans are the intermediate host Sporozoites enter bloodstream and infect liver cells where they become merozoites. Merozoites infect lots of RBC and some will differentiate into gametocytes which are taken up in the next blood meal.

Note: being heterozygous for sickle cell provides a protective advantage against malaria because merozoites can’t properly infect RBC.

Ascaris lumbricoides

Monoxenous nematode (non-segmented roundworm) which causes Ascariasis

Eggs first hatch in the intestine, then larvae travel to the lungs to start maturation into adults which they finish in the small intestine.

Treatments: Anthelmintic treatments which target microtubules and specific channels

Taenia saginata

Diheteroxenous cestode (segmented flatworm) which causes Taeniasis

Cows first eat the parasite in the form of cysticerci. Then humans eat undercooked cow meat which allows the parasite to mature into adults in the small intestine where they become very long and gross. Then they are pooped out. Contaminated grass will infect more cows.

Treatment: inducing paralysis in the worm