Flashcards in Parasitology Introduction Deck (24)
What is a parasite?
organism that lives in/on a host, getting its food at the expense of the host - can be obligate or facultative
What are three classes of parasites?
What are the three classes of helminths?
Nematodes (round worms)
Trematodes (flat worms)
Cestodes (tape worms)
What are the three classes of protozoa?
What are the three main classes of arthropods?
Found on blood and tissue (arthropod vector) or intestines (faecal-oral route)
What parasite causes malaria?
What is the vector for malaria transmission?
How can plasmodium falciparum be detected in the lab?
Using a Giemsa-stained blood film - think/thin
Describe how malaria is transmitted?
- sporozoites injected under the skin
- moves from blood to liver to mature
- merozoites re-enter circulation and invade RBCs
- sexual forms taken up by mosquitoes for further transmission
What parasite causes amoebic dysentery?
Describe how amoebic dysentery presents clinically
- trophozoite ingests RBCs using pseudopodia
- causes cysts/intestinal infections/liver abscesses
What parasite causes leishmaniasis?
Leishmania species - cutaneous/muco-cutaneous/visceral
Describe the symptoms of leishmaniasis
- weight loss
- hepato-splenomegaly (liver and spleen swelling)
How is a leishmania species transmitted?
Using a sand fly vector
Give examples of infections caused by nematodes
How is ascaris lumbricoides transmitted?
- eggs hatch in intestines
- larvae move to the lungs where they are re-swallowed
- worms develop in the small intestine
Give examples of infections caused by cestodes
How is taenia saginata transmitted?
Beef; cysts (worm formed) or eggs (cysts formed) in humans
How is taenia solium transmitted?
Pork; cysts or eggs ingested
How is echinococcus transmitted?
- ingestion of dog faeces
- eggs hatch and enter circulation
- cysts firm in the liver
Give an example of an infection caused by a trematode
Describe how a schistosomiasis species is transmitted
- ova excreted by humans into water
- miracidia released
- snail penetrated
- cercaria emerge
- human penetrated
- lung to liver to mature (on to bladder)
- eggs causing bladder/intestinal imflammation
- Katayama fever (acute febrile episode presents)