Helminth Infections

Question 1

What are helminths?

Answer 1

Worms

Question 2

What can helminths be divided into?

Answer 2

• Roundworms (nematodes)
• Flatworms (platyhelminths)

Question 3

How can the helminth life cycle be generalised?

Answer 3

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

Question 4

Which stage of the helminth life cycle is environmentally resistant?

Answer 4

Ova

Question 5

How are ova able to infect humans?

Answer 5

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

Question 6

What might ova infection result in?

Answer 6

Inflammatory response

Question 7

What is the migratory part of the helminth life cycle?

Answer 7

Larvae

Question 8

What do larvae allow?

Answer 8

Helminths to travel around the human to the correct area

Question 9

What do adult helminths produce?

Answer 9

Eggs

Question 10

How long can helminths persist for?

Answer 10

Many years

Question 11

What shape are round-worms in cross-section?

Answer 11

Circular

Question 12

How can flatworms be further classified?

Answer 12

• Tapeworms
• Flukes

Question 13

How do tapeworms and flukes differ?

Answer 13

Tapeworms are segmented, flukes are not

Question 14

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

Answer 14

• Ascaris
• Schistosomiasis
• Echinococcus
• Enterobius vermicularis

Question 15

What kind of helminths are ascaris?

Answer 15

Roundworms

Question 16

What do ascaris cause?

Answer 16

Intestinal infection in humans

Question 17

How are ascaris ova passed?

Answer 17

In human faeces

Question 18

How long can ascaris survive in human faeces?

Answer 18

Weeks

Question 19

Where do ascaris ova hatch once ingested in contaminated foods?

Answer 19

In the gut

Question 20

What happens to ascaris once hatched in the gut?

Answer 20

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

Question 21

What is the main pathology of ascaris?

Answer 21

Cause bowel obstruction

Can also cause anaemia

Question 22

How can ascaris cause anaemia?

Answer 22

From when they take blood

Question 23

How is ascaris diagnosed?

Answer 23

Stool sample containing the ova

Question 24

What is schistosomiasis caused by?

Answer 24

Schistosoma

Question 25

What kind of helminths are schistosomas?

Answer 25

Flukes

Question 26

What do schistosomas cause?

Answer 26

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

Question 27

How is schistosoma transmitted?

Answer 27

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*

Question 28

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

Answer 28

The adult will lay her eggs

Question 29

What does schistosomiasis cause?

Answer 29

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

Question 30

How is schistosomiasis diagnosed?

Answer 30

Ova in a stool sample

Question 31

What kind of helminths are echinococcus?

Answer 31

Tapeworms

Question 32

What is the normal host for enchinococcus?

Answer 32

Dogs and sheep, *but can infect humans as accidental hosts*

Question 33

How is enchinococcus transmitted?

Answer 33

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

Question 34

What does enchinococcus cause?

Answer 34

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

Question 35

What animals are enterobius vermicularis found in?

Answer 35

Only humans

Question 36

Where do enterobius vermicularis live?

Answer 36

In the large intestine

Question 37

How does enterobius vermicularis persist?

Answer 37

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

Question 38

What can insects act as?

Answer 38

Vectors for some disease causing organisms

Question 39

What is African sleeping sickness caused by

Answer 39

The Trypanosoma bruceigambiense

Question 40

What kind of organism is the Trypanosoma bruceigrambiense?

Answer 40

A protozoa

Question 41

What is African sleeping sickness transmitted by?

Answer 41

The tsetse fly

Question 42

What happens once the Trypanosoma bruceigambiense enters the blood?

Answer 42

It causes an immune response

Question 43

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

Answer 43

The surface antigens are constantly changing

Question 44

What does Trypanosoma bruceigambiense cause?

Answer 44

* Generalised lymphadenopathy * Hypergammaglobulinaemia

Question 45

What causes Chagas' disease?

Answer 45

Trypanosoma cruzi

Question 46

How is Chagas' disease transmitted?

Answer 46

The reduviid bug

Question 47

What does Chagas' disease produce?

Answer 47

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

Question 48

What is scabies caused by?

Answer 48

The mite Sarcoptes scabei

Question 49

What kind of organism is Sarcoptes scabei?

Answer 49

Parasite

Question 50

What does Sarcoptes scabei do?

Answer 50

Burrows under the skin

Question 51

What is responsible for the symptoms of scabies?

Answer 51

Both the eggs and the mites cause an allergic response

Question 52

What does scabies produce?

Answer 52

* Itching * Symmetrical inflammation of the body