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Flashcards in Helminth Infections Deck (52):
1

What are helminths? 

Worms 

2

What can helminths be divided into? 

  • Roundworms (nematodes)
  • Flatworms (platyhelminths)

 

3

How can the helminth life cycle be generalised? 

  1. Ova
  2. Larvae
  3. Adults which then produce ova

 

4

Which stage of the helminth life cycle is environmentally resistant? 

Ova

5

How are ova able to infect humans? 

Through ingestion of food contaminated by excrement, direct contant, or ingestion of contaminated meat

6

What might ova infection result in? 

Inflammatory response 

7

What is the migratory part of the helminth life cycle? 

Larvae 

8

What do larvae allow? 

Helminths to travel around the human to the correct area 

9

What do adult helminths produce? 

Eggs 

10

How long can helminths persist for?

Many years 

11

What shape are round-worms in cross-section? 

Circular 

12

How can flatworms be further classified? 

  • Tapeworms 
  • Flukes 

 

13

How do tapeworms and flukes differ? 

Tapeworms are segmented, flukes are not 

14

Give 4 types of helminths that can cause gut or tissue infections

  • Ascaris 
  • Schistosomiasis 
  • Echinococcus
  • Enterobius vermicularis 

 

15

What kind of helminths are ascaris? 

Roundworms 

16

What do ascaris cause? 

Intestinal infection in humans 

17

How are ascaris ova passed? 

In human faeces 

18

How long can ascaris survive in human faeces? 

Weeks

19

Where do ascaris ova hatch once ingested in contaminated foods? 

In the gut 

20

What happens to ascaris once hatched in the gut? 

Its larvae migrate to the intestine, or can enter the lung or liver 

21

What is the main pathology of ascaris? 

Cause bowel obstruction 

Can also cause anaemia 

22

How can ascaris cause anaemia? 

From when they take blood 

23

How is ascaris diagnosed? 

Stool sample containing the ova 

24

What is schistosomiasis caused by? 

Schistosoma 

25

What kind of helminths are schistosomas? 

Flukes 

26

What do schistosomas cause? 

Chronic infections in the hepatic, intestinal, and vesicle venous system 

27

How is schistosoma transmitted? 

Its ova are passed out of the intestines of infected humans in stool before its larvae infect snails. After development of the snail, the larvae penetrate human skin and travel to the mesenteric, vesical plexus etc., depending on the species 

28

What happens once the schistosoma larvae are in their desired location? 

The adult will lay her eggs 

29

What does schistosomiasis cause? 

  • Fever
  • Hepatospleenomegaly 
  • Skin rashes 
  • Dysentry 
  • Can affect lungs, bladder, or brain 

 

30

How is schistosomiasis diagnosed? 

Ova in a stool sample 

31

What kind of helminths are echinococcus? 

Tapeworms 

32

What is the normal host for enchinococcus? 

Dogs and sheep, but can infect humans as accidental hosts 

33

How is enchinococcus transmitted? 

The ova are passed in the animal faeces and ingested accidentally by the individual 

34

What does enchinococcus cause? 

Cysts to develop in the liver and lung, causing hydatid disease 

35

What animals are enterobius vermicularis found in? 

Only humans 

36

Where do enterobius vermicularis live? 

In the large intestine

37

How does enterobius vermicularis persist? 

The females pass out of the anus at night to lay eggs on the perianal skin. The subsequent perianal itching will result in contamination of the fingers with the larvae, which can then cause spread to other individuals and ingested to develop in the intestine, starting a new life cycle 

38

What can insects act as?

Vectors for some disease causing organisms 

39

What is African sleeping sickness caused by 

The Trypanosoma bruceigambiense 

40

What kind of organism is the Trypanosoma bruceigrambiense? 

A protozoa 

41

What is African sleeping sickness transmitted by?

The tsetse fly 

42

What happens once the Trypanosoma bruceigambiense enters the blood?

It causes an immune response

43

Why isn't the immune reponse against Trypanosoma bruceigambiense effective?

The surface antigens are constantly changing 

44

What does Trypanosoma bruceigambiense cause?

  • Generalised lymphadenopathy 
  • Hypergammaglobulinaemia 

 

45

What causes Chagas' disease?

Trypanosoma cruzi

46

How is Chagas' disease transmitted?

The reduviid bug

47

What does Chagas' disease produce?

  • Acute cutaneous oedema
  • Intermittent fever
  • Shock with significant mortality 

 

48

What is scabies caused by?

The mite Sarcoptes scabei 

49

What kind of organism is Sarcoptes scabei?

Parasite 

50

What does Sarcoptes scabei do? 

Burrows under the skin 

51

What is responsible for the symptoms of scabies? 

Both the eggs and the mites cause an allergic response 

52

What does scabies produce?

  • Itching
  • Symmetrical inflammation of the body