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Flashcards in Introduction to Parasites Deck (34):
1

What is a parasite?

An organism that lives in another and gets its food at the expense of the host

2

What parasitic disease causes the most deaths globally?

Malaria

3

What are the 3 classification of parasites?

-Protozoa
-Helminths
-Arthropods

4

What are protozoa?

-Microscopic, unicellular organisms
-Can be free-living or parasitic in nature

5

How are protozoa transmitted?

-Protozoa that live in human's intestines= fecal-oral route
-Protozoa that live in blood/tissue=arthropod route

6

What kind of infection is malaria?

Protozoan

7

Describe malaria.

-Mosquito-borne disease caused by a parasite
-Patient often experiences fever, chills and flu like symptoms
-Left untreated they may develop sever complications and die

8

What is the name of the parasite involved in malaria?

Plasmodium spp
P. falciparum has the highest mortality rate

9

How is malaria diagnosed/

-Giesma stained blood fil shows infected red cells
-Thick and thin blood films
Variety of rapid diagnostic testing

10

Describe the life cycle of plasmodium spp.

-Sporozoites are injected under the skin
-They travel through th blood and enter the liver
-They mature in the liver and re-enter circulation as merozoites
-They invade RBC, multiply and lyse cells
-Sexual form is then taken up by mosquito

11

How can the spread of malaria be controlled?

-Insecticide treated mosquito nets
-Prophylaxis
-Malaria vaccine currently being researched

12

What kind of infection is amoebic dysentery?

Protozoal

13

What causes amoebic dysentery?

Entamoeba histolytica

14

What are the clinical signs of amoebic dysentery?

-Diarrhoea with blood/pus
-Intestinal and extra intestinal infections
-Liver abscess in late disease

15

What would be found on microscopy of amoebic dysentery?

Cysts in formed stool

16

What do trophozoites do in amoebic dysentery?

Ingest red cells by throwing out pseudopodia

17

What are nematodes?

Roundworms

18

What are cestodes?

Tapeworms

19

What are trematodes?

Flatworms

20

How is enterobiasis diagnosed?
Nematode

-Press adhesive sellotape against perianal region in the morning
-Ova seen on microscopy

21

Describe Ascaris lumbricoides.

-Nematode
-Ingested eggs hatch in the intestine
-Larvae carried by circulation to lungs
-Swallowed again
-Adult worms develop in and inhabit small intestine
-Ova seen in faeces by microscopy

22

What symptoms are usually seen with Ascrais lumbricoides?

-Often asymptomatic
-Transient pulmonary symptoms in Loefler's syndrome
-Mass of worms may obstruct small intestine or common bile duct

23

What are 2 examples of cestodes?

-Taenia saginata (beef)
-Taenia solium (pork)

24

What are the hosts in the Taenia spp?

-Larval cysts ingested in meat (intermediate host)
-Adult tapeworm in human (definitive host)

25

How is the taenia spp diagnosed?

-Tissue cysts in humans infected with T solium- cysticercosis
-Ova in stools on microscopy

26

What is Echinococcus sp carried by?
Trematode

Dogs, wolves and foxes

27

Describe the life cycle of Ecjinococcus.

-Humans ingest eggs (dog faeces)
-Eggs hatch and enter circulation
-Hydatid cysts forms in liver
-Surgical resection must involve whole cyst

28

What is serology?

Detection of antibodies

29

What diagnostic principles apply to parasitology?

-Culturing is rarely possible
-Blood films (thick/thin) for malaria
-Serology
-Identification of parasites in host tossue or excreta
-Microscopy ate P,C and O in faeces

30

What is helminth infection often accompanied by?

-Eosinophilia
-Elevate IgE

31

What can Schistosoma haematobium cause?

-Haematuria
-Bladder cancer

32

What are the 3 major species of Schistosomes?

-S. haematobium (bladder)
-S. mansoni (intestinal)
-S. japonicum (intestinal)

33

Describe infection of schistosomiasis.

-Eggs excreted in urine or faeces
-Miracidia released in fresh water
-Penetrate body of snail (intermediate host)
-Cercaria emerge from snails after 4-6 weeks
Penetrate human skin
-Migrate through lungs to liver
-Mature in liver into worms that migrate to mesenteric or bladder venules
-Lay eggs that cause inflammation in bladder or intestinal wall
Katayma fever- acute febrile episode

34

What kind of parasite causes schistosomiasis?

Trematode