[MOD3] Parasitic Protozoans

• Cyst - Infective stage of Entamoeba histolytica
• Cysts are typically found in formed stool.
• Trophozoites are typically found in diarrheal stool.
• Entamoeba histolytica mode of transmission

  Ingestion of mature cysts from fecally contaminated food, water, or hands
• Amoebic surface protein in E. histolytica trophozoites

  Gal/GalNAc lectin binds galactose and N-acetylgalactosamine, allowing the adherence of amoebas to host cells
• Amoebic liver abscess (ALA) - most common extraintestinal form of amoebiasis
• Fever and right upper quadrant pain - cardinal manifestations of ALA
• Treatment for E. histolytica:

  Metronidazole

  5-nitroimidazole derivatives (tinidazole and secnidazole)

  Diloxanide furoate
• Giardia lamblia - flagellate in the duodenum, jejunum, and upper ileum of humans
• Cyst - infective stage of Giardia lamblia
• Adhesive disc - found in the ventral side of G. lamblia, used for attachment
• Axostyle - distinct medial line present in the G. lamblia trophozoite
• Bilateral symmetry - Characteristic of G. lamblia trophozoites
• Entamoeba histolytica - pseudopod-forming, non-flagellated protozoan parasite
• Dorsal side of G. lamblia trophozoite is convex
• Ventral side of G. lamblia trophozoite is concave
• "Rotten egg" odor - Clinical manifestation of Giardiasis
• Balantidium coli - largest protozoan parasite affecting humans, only ciliate known to cause human disease
• Cytostome - food acquisition in Balantidium coli
• Cytopyge - waste excretion in Balantidium coli
• Rounded base and wide neck - characteristic of ulcer of Balantidium coli trophozoites
• Hyaluronidase - proteolytic enzyme secreted by B. coli trophozoites that digest the epithelium of the large intestine
• Pigs - reservoir host of Balantidium coli
• Plasmodium spp. - group of parasites that cause malaria
• female Anopheles mosquito - vector/definitive host of Plasmodium spp.
• Plasmodium spp. asexual cycle - occurs in humans
• Plasmodium spp. sexual cycle - occurs in the Anopheles mosquito
• Humans - intermediate host of Plasmodium spp.
• Asexual cycle

  Schizogony - formation of merozoites
• Asexual cycle

  Gametogony - formation of gametocytes
• Sexual cycle

  Sporogony - formation of sporozoites
• Hypnozoite - merozoites of P. vivax and P. ovale that re-invade the liver
• Microgametocyte - male gametocyte
• Macrogametocyte - female gametocyte
• Microgametocytes or macrogametocytes - ingested by female mosquitoes during a blood meal
• Ookinete - motile zygote that penetrates the mosquito's gut
• Sporozoites - escape from the oocyst and enter the salivary glands of the mosquito
• Sporozoites - injected into another human by the mosquito during a blood meal
• Pre-patent period - interval from sporozoite injection to detection of parasites in the blood
• Incubation period - time between sporozoite injection and the appearance of clinical symptoms