Parasitic Infections Flashcards Preview

Y2 MCD Microbiology RI > Parasitic Infections > Flashcards

Flashcards in Parasitic Infections Deck (82)
Loading flashcards...
1

Define parasite.

An organism living in or on a host and dependent on the host for nutrition – causing damage

2

What is the difference between an endoparasite and an ectoparasite?

Endoparasite – exist INSIDE the host

Ectoparasite – exist on the host

3

What are the two groups of endoparasites and what are the features of organisms within these two groups?

Protozoa
Metazoa

4

State the classes of organisms within the two groups of endoparasites.

Protozoa
 Amoeba
 Coccidia
 Ciliates
 Flagellates

Metazoa
 Roundworms
 Flatworms
 Flukes

5

Give some examples of amoeba.

Entamoeba histolytica
Entamoeba dispa

6

Give some examples of coccidia.

Plasmodium species
Toxoplasma
Cryptosporidium

7

Give an example of a ciliate.

Balantidium coli

8

Give some examples of flagellates.

Trypanosoma
Trichomonas
Giardia
Leishmania

9

What is the main difference between the two types of amoeba?

Entamoeba histolytica can cause invasive amoebiasis

Entamoeba dispar is a normal commensal of the GI tract

10

What is amoeba infection caused by?

Ingestion of mature cysts in food or water contaminated by faeces

11

Describe how E. histolytica infection causes disease.

The cysts enter the small intestine and release active amoebic particles (trophozoites), which invade the epithelial cells of the large intestines, causing flask-shaped ulcers

Infection can spread from the intestines to other organs

Invasive amoebiasis may often cause amoebic liver abscesses

12

How many nuclei are there in mature cysts?

4

13

What are the treatment options for amoebiasis?

Nitroimidazole derivatives (kills trophozoites but not the cysts)

Parmomycine or Diloxanide Furoate

14

What are the five types of plasmodium that cause malaria?

Falciparum
Malariae
Vivax
Ovale
Knowlesi

15

What are the two types of host for plasmodium?

Human
Female anopheles mosquito

16

What are the two stages of malaria in humans?

Liver
Blood

17

Describe the symptoms of malaria.

PAROXYSMAL (occurs every 4-8 hours)
Fever
Chills
Headaches
Vomiting
Muscle pain

18

State some complications of malaria.

Severe anaemia (due to intravascular haemolysis)
Cerebral malaria
Liver failure
Shock
Pulmonary oedema
Abnormally low blood sugar
Kidney failure
Swelling and rupturing of the spleen

19

What are the treatments for uncomplicated malaria?

Chloroquine

20

What is the treatment for severe malaria?

Artemisinin-based combination therapy

21

How is malaria diagnosed?

Blood film (+ Giemsa stain)

22

What are the routes of infection of toxoplasma gondii?

Eating undercooked meat of animals harbouring tissue cysts

Consuming food or water contaminated with cat faeces

Blood transfusion

Organ transplantation

Transplacentally from mother to foetus

23

Which group of patients are particularly vulnerable to toxoplasma infection?

Immunocompromised and in pregnancy - the fetus

24

What can toxoplasma infections cause in immunocomprimised individuals?

CNS disease
Brain lesions
Pneumonitis
Retinochoroiditis

25

What does cryptosporidium cause?

DIARRHOEA (mainly in the immunocompromised)

26

How is it treated?

Fluid rehydration

27

How are most diarrhoeal protozoal diseases diagnosed?

Stool examination

28

What are the reservoirs of balantidium coli?

Primates
Rodents
Pigs

29

What are the effects of balantidium coli infection in immunocompromised patients?

Persistent DIARRHOEA
Dysentery
Abdominal pain
Vomiting
Nausea

Note:
If left untreated can cause perforation of the colon

30

How can drinking water be cleared of ovoid giardia lamblia cysts?

Filtration

Ovoid cysts can survive standard chlorination procedures

31

What is the main symptom of giardiasis?

DIARRHOEA

32

How is giardia transmitted?

Faeco-oral

33

What are the acute symptoms of giardiasis?

Diarrhoea
Greasy stools that tend to float
Stomach or abdominal cramps
Nausea/vomiting
Dehydration

34

What is the treatment for giardia?

Metronidazole - doesn't kill cysts only the trophozoites

35

How is trichomonas transmitted?

Sexually transmitted

36

Where does trichomonas infection mainly tend to reside?

Urethra

37

What are the symptoms of trichomoniasis?

Up to 50% aysmptomatic
Dysuria
Vulval itching
Vaginal discharge
Offensive smelling urine

38

What effect does trichomonas infection have on HIV transmission?

It enhances HIV transmission

39

What is the treatment for trichomoniasis?

Metronidazole

40

Can adult worms multiply in man?

No

41

In which subset of the population is there a significant burden of worms?

School-aged children – this has a massive impact on their development

42

What are the three groups of Helminths(metazoa)? Give some examples of each.

Roundworms (nematodes)
 Ascaria
 Hookworms
 Filaria
 Strongyloides

Flatworms (cestodes)
 Taenia (tapeworms)

Flukes (trematodes)
 Schistosoma

43

Where do the adult ascaria worms live?

Small intestine

44

Describe the passage of ascaria larvae once they hatch in the small intestine.

Infective eggs are swallowed

The larvae hatch in the small intestine and invade the intestinal mucosa

They are carried via the portal and systemic circulation to the lungs

The larvae mature further in the lungs, penetrate the alveolar walls, ascend the bronchial tree and are swallowed

When they reach the small intestine, they mature into adult worms

45

How long can adult ascaria live?

1-2 years

46

Describe the symptoms of ascariasis.

Often asymptomatic

Infections with a large number of worms can cause abdominal pain or intestinal obstruction

Malnourishment (because of worms feeding on contents of small intestine)

Loeffler’s pneumonia – penetration of larvae into lungs leads to pools of blood and epithelial cells clogging the airspaces in the lungs (resulting bacterial infections can be fatal)

47

What is the treatment for ascariasis?

Albendazole or Mebendazole

48

How are most helminth infections diagnosed?

Stool examination

49

Describe the passage of hookworm larvae across the body.

The same as ascaria

50

Where do adult hookworms live?

Small intestine

Attached by their buccal capsules to the villi of the small intestine

51

What is a key feature of hookworm infection and what is this caused by?

Iron deficiency anaemia – caused by localised bleeding in the small intestine

52

What is the treatment for hookworm infection?

Albendazole or Mebendazole

53

What is the biological name whipworm?

Trichuras trichiura

54

Where do adult whipworms live?

Caecum and ascending colon

55

What are the symptoms of whipworm infection?

Blood diarrhoea and anaemia (due to severe vitamin and iron loss)

Inflammation of intestinal wall

Can develop rectal prolapse

56

What is the treatment for whipworm infections?

Albendazole or Mebendazole

57

What is a potential therapeutic use of whipworms?

Helminth therapy for allergies and autoimmune diseases

58

What are the two forms of filaria?

Brugia malayi
Wucheria bancrofti

59

Describe the location of microfilariae in the blood.

They are found in the peripheral blood at night

They are found in the deep veins during the day

60

How is lymphatic filariasis diagnosed?

Blood smear

Antigen detection with immunochromatic test (ELISA)

61

What is a distinguishing feature of Loiasis?

Female worms can get into the eye and cross under the conjunctiva so you see something wriggling in your vision

62

What is the insect vector in Loiasis?

Chyrops fly

63

What are the three main types of flatworm for which humans are the only definite host?

Taenia solium
Taenia asiatica
Taenia saginata

64

Describe the symptoms of flatworm infection.

Most people are asymptomatic

Abdominal pain
Weight loss
Loss of appetite
Upset stomach

NOTE: people with T. saginata infection tend to have more symptoms

65

How is flatworm infection diagnosed?

Stool examination – tapeworm segments are found in the stool or identification of eggs in the stool

66

What important condition does Taenia solium cause?

Cysticercosis - commonest acquired cause of epilepsy worldwide

67

What is the treatment for flatworm infections?

Praziquantel

68

What are the three main types of schistosoma?

Schistosoma mansoni
Schistosoma haematobium
Schistosoma japonicum

69

What is the intermediate host in schistosoma?

Freshwater snails

70

Where do the adult worms live in schistosomiasis?

Venule

71

Where do the eggs progressively move to?

Small intestine (mansoni and japonicum)
Bladder and ureters (haematobium)

72

Describe the symptoms of schistosomiasis.

Possible rash or itchy skin
Fever
Chills
Cough
Muscle aches
Most people have NO SYMPTOMS in early stages of infection

73

What is the treatment of schistosomiasis?

Praziquantel

74

Name some ectoparasites.

Sarcoptes scabiei – Scabies (causes rash)
Pediculus humanis capitis (head louse)
Pediculus humanis corporis (body louse)
Pthirus pubis (crab louse)

75

How are ectoparasites transmitted?

Direct contact

76

What are the features of protozoa?

 Unicellular
 Eukaryotes (membrane bound nucleus)
 Some have insect vectors
 NO eosinophilia

77

What are the features of metazoa?

 MULTIcellular
 They are helminths/worms
 Free living, intermediate hosts and vectors
 Cause eosinophilia if they invade the blood
Cycles involve insects vectors and intermediate hosts
For most - few zoonoses

78

What are the reservoirs of E. histolytica?

Humans are the only reservoir

79

What are the complications of Trichomoniasis

Detrimental outcome on pregnancy and is associated with preterm delivery and low birth weight

80

Define parasite

Organism living in or on the host and dependent on it for nutrition - causing damage

81

How do you get infected by a fluke cercaria?

Patient has to be in infected water so cercaria can penetrate the skin

82

How are scabies treated?

Scabicides