Condensed info of Parasites (Theoretical aspect of Colloqium) Flashcards
<strong>GENERAL Life Cycle of Trypanosoma Rhodesiense, Trypanosoma Gambiense, Trypanosoma Brucei, Trypanosoma Cruzi</strong>
Life Cycle:
- Tsetse fly takes blood meal (injects metacyclic trypomastigotes)
- Injected trypomastigotes transform in the bloodstream
- Trymastigotes multiply by binary fission
- Tsetse fly takes blood meal (the ones in the blood stream)
————— DIAGNOSTIC STAGE ^
- Blood stream trymastigotes become procyclic in tsetse fly’s mid-gut
- Procyclic trymastigote leave mid-gut and become epimastigotes
- Epimastigotes multiply in salivary gland and become metacyclic again
—————– INFECTIVE STAGE ^
GENERAL Life Cycle of Leishmania Donovani and Tropical
Host: Humans (Definitive)
Female sandfly vector (Intermediate)
Only the female fly can suck blood
Life Cycle:
- Sandfly takes blood meal (inects promastigotes into skin)
- Promostigotes are phagocytized by macrophages
- Promastigoes become amostigote whilst in macrophages
- Amastigotes multiply in cells
———-^ DIAGNOSTIC STAGE
- Sandfly takes a blood meal (ingests infectied macrophages/ containing amastigote form of parasite)
- Amastigotes become promastigotes whilst in mid-gut of sandfly
- They divide and migrate to proboscis (while in mid-gut)
——— ^ INFECTIVE STAGE
GENERAL Life cycle of Giardia Lamblia - (Lamblia Intestinalis)
Giardiasis (Beaver Fever)
Host: Humans and other mammals
Life Cycle:
- Ingestion of dormant cysts
- Excystation trophozite emerge to an active stae
- Trophozite undergo asexual replication
- Not everyone exhibits symptoms
- Encystation during transit to colon
- Cysts and trophozites expelled in the feces
- Only cysts can susrvive outside of host
- Cysts survive for weeks-months in cold water
GENERAL Life Cycle of Trichomanas Hominis and Vaginalis
Host: Humans (Definitive)
Life cycle:
- Trophozoite in vaginal and prostatic secretions and urine
- Multipliesbylongitudinalbinaryfission
- Trophozoite in vagina or orifice of urethra
GENERAL Life Cycle of Entamoeba Histolytica
LIFE CYCLE:
- Cysts and trophozoites are passed in feces
- Infection occurs by ingestion of mature cysts in fecally
contaminated food, water, or hands (fecal-oral route)
- Excystation occurs in the small intestine and trophozoites are
released, which migrate to the large intestine.
- The trophozoites multiply by binary fission and produce cysts,
and both stages are passed in the feces
- Cysts can survive days to weeks in the external environment
- Trophozoites passed in the stool are rapidly destroyed once
outside the body, and if ingested would not survive exposure to
the gastric environment.
- The trophozoites can be confined to the intestinal lumen of individuals (asymptomatic carriers) , passing cysts in their stool.
GENERAL Life Cycle of Plasmodium;
Life Cycle:
- Mosquito takes blood meal and injects sporozoites
- Travels to liver and infects it
- Mature into schizonts, which rupture and release merozoites
- In ertythrocytes, they undergo asexual multiplication
- Ring stage trophozites mature into shizonts which rupture and relase merozoites
- Some parasites differentiate into sexual erythrocytic stages
(gametocytes)
- Blood stage parasites = CLINICAL MANIFESTATION OF DISEASE
- The gametocytes are ingested by an anopheles mosquito during blood meal
- The parasites’ multiplication in the mosquito is known as the sporogonic cycle.
- In the mosquito’s stomach, the microgametes penetrate the macrogametes generating zygotes.
- The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts.
- The oocysts grow, rupture, and release sporozoites, which make their way to the mosquito’s salivary glands.
GENERAL Life Cycle of Toxiplasma Gondii
(Cat = Definitive host)
Life Cycle:
-
- Begins with ingestion of bradyzoite tissue cysts
- Gamete fusion results in zygotes which develops in a riggit wall and is secreted in feces as unsporulated oocyst
- After 2/3 days exposure to air, non infectious oocysts sporulate to produce sporozoite progeny.
- Sporulated oocyst are ingested by intermediate host (birds/rodents)
GENERAL Life Cycle of Fasciola Hepatica - Liver Fluke
Hosts: Mammals (definitive)
Snails (intermediate)
Aquatic Vegetation (2nd intermediate)
Life Cycle:
- Unembroynated eggs are passed in feces
- Embryonated eggs in water
- Miracidia hatch, penetrate snail
- In the snail, parasites undergo several development stages (sporocysts, rediae, cercariae)
- Cercariae are released from snail and encyst on water plants
- Metacercariae on water plant ingested by human, sheep or cattle
- Metacercariae exists in duodenum
- Develop into adult flukes in the biliary ducts
GENERAL Life cycle of Dicrocoelium dendrticum - Lancet liver fluke
Life Cycle:
-
- Embryonic eggs containing miracidia are shed in feces of definitive Hosts
- Eggs are ingested by 1st intermediate host (snail)
- When miracidia hatch they migrate through the gut wall and settle into Muscular tissue where they become sporocysts
- Sporocysts migrate into digestive gland where they give rise to several daughter sporocysts inside each sporocyst cercariae are produces
- Cercariae migrate to respiration chamber where they are shed in a slime ball from snail
- After a slime ball is ingested by 2nd intermediate host(ant) cercariae migrate to hemocoel where they become metacercariae
- When ant is eaten by definitive host metacercariae cyst in small intestine
- Worms migrate to bile ducts where they mature into adults
GENERAL Life Cycle of Opisthorchis Felineus
LIFE CYCLE:
- Embryonated eggs passed in feces.
- Eggs are ingested by the snail.
- Free-swimming cercariae encyst in the skin or flesh or fresh water fish.
- Metacercariae in flesh or skin of fresh water fish are ingested by the human host.
- Excyst in duodenum.
- Adult in biliary duct.
GENERAL Life Cycle of Genus Schistosoma (Blood Flukes)
LIFE CYCLE:
- Eggs released by feces or urine hatch and release miracidia
- Miracidia swim and penetrate specific snail hosts
Stages in snail include 2 generations of sporocysts and production
of cercariae
- Cercariae are released and swim to penetrate skin of human host
and shed their tail becoming schistosomula
- Schistosomulamigratetotheliveranddevelopandexitwhen
mature
- Male and female adult worms copulate and reside in mesenteric
venule
GENERAL Life Cycle of: Echinoccus Granulosus - Definitive host = DOGS, Intermediate host = SHEEP, GOATS, CATTLE, Tapeworm
LIFE CYCLE:
-
- Adult resides in small intestine of definitive hosts, dogs or other canids
- Gravid proglottids release eggs, embryonated eggs in feces
- Oncosphere hatches, penetrates intestinal wall
- Oncosphere develops into a cyst, in liver lungs
- After ingestion, protoscolices evaginate, attach to intestinal mucosa
- Scolex attaches to intestine
GENERAL Life Cycle of: Taenia Saginata
Beef Tapeworm
Differences between beef & pork tenia; scolex, number of uterine
branches in gravid proglottids, human infection
CATTLE = Intermediate host, HUMAN = Definitive host only
Scolex with 4 suckers, no rostellum
Life Cycle:
- Ingestion of raw/ undercooked beef contains T. S larvae
- Larvae gets digested out of beef in human intestinal system
- Worm attaches on intestinal mucosa of small intestine
- Tapeworm will digest food and grow longer. Mature tapeworms release 10 single gravid proglottids daily via feces or will be released from anus
- Proglottids are motile and will shed eggs as it moves. These eggs can remain viable for several days
GENERAL Life Cycle of: Ascaris Lumbricoides - Giant Roundworm
LIFE CYCLE:
- Adult worms live in lumen of small intestine, female may produced 200, 000 eggs per day which are passed with feces
- Fertile eggs embryonate and become infective depending on conditions
- After infective eggs are swallowed, larvae hatch, invade intestinal mucosa and carried via portal then the lungs
- Larvae mature further in lungs, penetrate alveolar walls, ascend bronchial tree to throat and are swallowed
GENERAL Life Cycle of Trichinella Spiralis
Host: Rodents Pigs Bears and Humans
Life Cycle:
- After ingestion of undercooked meat containing encysted larvae (infective)
- Due to the exposure of gastric acid and pepsin the larvae are released from the cysts
- Larvae invade small bowel mucosa where they develop into adult worm
- Female release larvae that migrate to striated muscle where they encyst
