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Year 2 Clinical Pathology > 1. Parasites > Flashcards

1. Parasites Flashcards

1
Q

What is a parasite?

A

An organism that lives in/on another organism (HOST) and benefits by deriving nutrients.
-NB. doesn’t necessarily cause disease

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2
Q

What is meant by symbiosis?

A

A close, long-term interaction between 2 different species.

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3
Q

What is meant by mutualism?

A

An association in which both species benefit from the interaction.

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4
Q

What is meant by commensalism?

A

An association where parasite only is deriving benefit without causing injury to the host.

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5
Q

What is meant by parasitism?

A

An association where the parasite derives benefit and the host gets nothing in return but always suffers some injury.

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6
Q

What are the 3 classes of host?

A

Definitive
Intermediate
Paratenic

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7
Q

What is a definitive host?

A

Harbours adult parasite/where parasite carries out sexual reproduction.
-Normally man in human parasitic infections

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8
Q

What is an intermediate host?

A

Harbours larvae/asexual stages.

-Some parasites have more than one intermediate host

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9
Q

What is a paratenic host?

A

Where parasite remains viable without further development.

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10
Q

What are the 2 main types of parasite?

A

PROTOZOA (mirco)

HELMINTHS (macro) - worms

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11
Q

What are the 4 main subdivisions of protozoa?

A

Flagellates
Amoeboids
Sporozoans
Tryponosomes

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12
Q

What are the 2 main subdivision of helminths?

A
  • Platyhelminths (flatworms)

- Nematodes (round worms)

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13
Q

What are the 2 main subdivisions of platyhelminths (flatworms)?

A
  • Cestodes (tape worms)

- Trematodes (flukes)

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14
Q

What are the 2 main subdivisions of nematodes (round worms)?

A
  • Intestinal nematodes

- Tissue nematodes

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15
Q

Give an example of a cestode.

A

Taenia sp

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16
Q

Give an example of a trematode.

A

Schistosoma sp

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17
Q

Give an example of an intestinal nematode.

A

Ascaris lumbricoides

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18
Q

Give an example of a tissue nematode.

A

Wuchereria bancrofti

|&raquo_space; elephantitis

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19
Q

Give the 3 types of life cycle of a parasite?

A
  • Direct
  • Simple indirect
  • Complex indirect
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20
Q

What is a direct life cycle?

A

Parasites infect a single host (no intermediate hosts).

- eg. bird eats infective eggs&raquo_space; mature&raquo_space; sheds parasitic eggs

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21
Q

What is an indirect life cycle?

A

Parasite life cycle involves 2 hosts (1 intermediate).

-eg. bird sheds parasitic eggs&raquo_space; slowbug eats them&raquo_space; infective larvae in slowbug&raquo_space; bird eats slowbug

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22
Q

What is a complex indirect life cycle?

A

Parasite life cycle involves more than 2 hosts.

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23
Q

Name 5 parasites to study in greater depth.

A 
Ascariasis
Schistosomiasis
Hydatid disease
Malaria
Cryptosporidiosis
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24
Q

What type of parasite is ascariasis?

A

Intestinal nematode

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25
Q

Where is ascariasis mainly distributed?

A

East Asia

26
Q

What type of life cycle does ascariasis have?

A

Direct life cycle

ingest eggs&raquo_space; develop in faeces&raquo_space; gut&raquo_space; portal circulation&raquo_space; lungs&raquo_space; swallowed&raquo_space;back into intestine

27
Q

How is ascariasis spread?

A

Poor hygiene

-faecal-oral (ingest eggs)

28
Q

What are the symptoms of ascariasis?

A
  • INTESTINAL (malnutrition, worm burden)

- LUNG MIGRATION (Loefflers syndrome - dry cough, haemoptysis, wheeze)

29
Q

How is ascariasis treated?

A

Albendazole (benzimidazole)

-prevents glucose absorption by worm

30
Q

What type of parasite causes Schistosomiasis (AKA Bilharzia)?

A

Trematode/fluke

S. mansoni, S. intercallatum, etc.

31
Q

Where is Schistosomiasis mainly distributed?

A

Africa

32
Q

What type of life cycle does Schistosomiasis have?

A

Indirect life cycle

-snails are intermediate host

33
Q

What are the symptoms of Schistosomiasis? (3)

A
  • Swimmers itch
  • Katayama fever
  • Chronic Schistosomiasis
34
Q

What are the symptoms of S haematobium (type of Schistosomiasis)? (3)

A

URINARY

  • Haematuria
  • Bladder fibrosis
  • Squamous cell bladder cancer
35
Q

What are the symptoms of S. mansoni/intercallatum/japonicum/mekongi (types of Schistosomiasis)?

A

HEPATIC/INTESTINAL

  • portal hypertension
  • liver cirrhosis
36
Q

How is Schistosomiasis diagnosed?

A 
URINARY -serology
-terminal stream microscopy
HEPATIC/INTESTINAL -serology
-stool microscopy
-rectal snip microscopy
37
Q

How is Schistosomiasis treated?

A

Praziquantel (increases ionic permeability tetanic concentration&raquo_space; detachment)

38
Q

How is Schistosomiasis prevented?

A
  • Chemicals to kills snails
  • Chemoprophylaxis
  • Avoid infested water
39
Q

What type of parasite causes hydatid disease?

A

Platyhelminth-Cestode-Tapeworm

macro-parasite

40
Q

What causes hydatid disease?

A

Echinococcus sp.

granulosus = cystic, multilocularis = alveolar

41
Q

What are the normal host in hydatid disease?

A

Sheep & dogs

-humans are accidental hosts

42
Q

What type of life cycle does hydatid disease have?

A

Indirect

-humans = intermediate hosts

43
Q

What are the symptoms of hydatid disease?

A
  • Cysts (70% = liver, 20% = lungs)
  • 2* bacterial infection
  • cyst rupture&raquo_space; hypersensitivity

NB. may remain asymptomatic for years

44
Q

How is hydatid disease diagnosed?

A

Imaging

Serology

45
Q

How is hydatid disease prevented?

A
  • Regularly worm dogs
  • Hand hygiene
  • Safe disposal of carcasses
46
Q

What parasite is malaria caused by?

A

Protozoa-sporozoan
-Plasmodium
(micro-parasite)

47
Q

What 4 species of Plasmodium cause malaria?

A

P. falciparum (70%)
P. vivax
P. ovale
P. malariae

48
Q

What type of life cycle does malaria have?

A

Indirect

-anopheles(mosquito) = vectors

49
Q

Where is malaria mainly distributed?

A

Africa (& Asia/South America)

50
Q

What are the basic stages of the malaria life cycle?

A

Mosquito bite
» liver
» blood
» mosquito drinks blood

51
Q

What is the clinical presentation of malaria?

A
  • ruptured RBCs block capillaries&raquo_space; inflammatory reaction
  • fever & rigors
  • cerebral (confusion, coma)
  • renal failure
  • hypoglycaemia
  • anaemia
52
Q

How is malaria diagnosed?

A
  • Thick & thin microscopy
  • Serology (detect antigen)
  • PCR (detect malarial DNA)
53
Q

What parasite is Cryptosporidiosis caused by?

A

Cryptosporidium parvum & hominis

-sporozoan, mirco-parasite

54
Q

What are the symptoms of Cryptosporidiosis?

A
  • diarrhoea with mucus
  • bloating, cramps, nausea, fever
  • usually self-limiting (>2 weeks)
55
Q

How is Cryptosporidiosis spread?

A

Faecal-oral route

  • human-human spread
  • human-animal spread
56
Q

Who are most at risk of Cryptosporidiosis?

A

HUMAN-HUMAN SPREAD: pool user, healthcare workers, parents, travellers
HUMAN-ANIMAL SPREAD: backpackers, campers, farm workers

57
Q

How is Cryptosporidiosis diagnosed?

A

Faeces sample (acid fast staining/antigen detection by EIA)

58
Q

How is Cryptosporidiosis treated?

A

SYMPTOMATIC - rehydration, nitazoxanide

59
Q

How is Cryptosporidiosis treated in immunocompromised patients?

A
  • Paromomycin (kill parasite)
  • Nitazoxanide
  • Octreotide (reduce cramps)
  • HAART (HIV patients)
60
Q

How is Cryptosporidiosis prevented?

A

Hand hygiene
Pasteurise dairy products
Boil drinking water

61
Q

Name 5 commonly used anti-protozoal treatments.

A 
Metronidazole
Pentamidine
Nitazoxanide
Pyrimethamine
Anti-malarials
62
Q

Name 4 commonly used anti-helminthic treatments.

A

Albendazole
Mebendazole
Ivermectin
Praziquantel

Year 2 Clinical Pathology (13 decks)

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