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π“œπ‘’π’Ήπ’Ύπ’Έπ’Άπ“ π“œπ’Ύπ’Έπ“‡π‘œπ’·π’Ύπ‘œπ“π‘œπ‘”π“Ž > Pathogenesis of Parasitic Infections > Flashcards

Pathogenesis of Parasitic Infections Flashcards

1
Q

What are the two main types of leishmaniasis?

A

➝ Visceral and Cutaneous

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2
Q

What are the three geographical regions affected by visceral leishmaniasis?

A

➝ Asia
➝ Middle east/africa/asia
➝ Latin america

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3
Q

What type of visceral leishmaniasis affects Asia?

A

➝ Leishmania donovani

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4
Q

What type of visceral leishmaniasis affects the Middle east & Africa?

A

➝ L.Infantum variants

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5
Q

What type of visceral leishmaniasis affects Latin America?

A

➝ L. Chagasi

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6
Q

What types of cutaneous leishmaniasis affect the new world?

A

➝ L.braziliensis/amazonensis/mexicana

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7
Q

What is Leishmaniasis caused by?

A

➝ Sand fly

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8
Q

Describe the lifecycle of leishmaniasis?

A

➝ The sandfly bites and transmits a promastigote
➝ The promastigote invades immune cells like macrophages
➝ Inside the macrophage it forms nests of amastigotes
➝ the cells eventually burst which release lots of amastigotes and infect other cells which can be taken up by the fly

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9
Q

What is the vector of leishmaniasis?

A

➝ Lutzomyia/phlebotomus

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10
Q

In what regions are sandflies common and who do they affect?

A

➝ Tropical regions

➝ people who live in housing of poor standard such as adobe

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11
Q

What type of an infection is leishmaniasis?

A

➝ Zoonotic

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12
Q

What is the sylvatic and domestic reservoir of leishmaniasis?

A

➝ sylvatic ➝ rodents

➝ domestic ➝ dogs

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13
Q

Describe the progression of cutaneous leishmaniasis after a bite?

A

➝ There is a papule that forms and spreads

➝ the center becomes necrotic and ulcers form

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14
Q

What happens if you get infected as a child with cutaneous leishmaniasis?

A

➝ early immunity to that form of leishmania

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15
Q

When does diffuse cutaneous leishmaniasis occur?

A

➝ When there is lack of an immune response to the leishmania

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16
Q

Describe the progression of mucocutaneous leishmaniasis?

A

➝ a small proportion of individuals get congested noses
➝ lesions occur in the mucus membranes
➝ lesions occur and destroy the nasal septum

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17
Q

When do people get infected with mucocutaneous leishmaniasis?

A

➝ as children

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18
Q

What are the three phases of cutaneous leishmaniasis?

A

➝ Acute lesions
➝ Latency
➝ Relapse (rare)

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19
Q

Describe the pathogenesis of acute lesions in cutaneous leishmaniasis?

A

➝ Tissue damage is caused by inflammatory response to the presence of parasites in macrophages
➝ parasite killing by Th1 proinflammatory responses and macrophage killing

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20
Q

Describe the pathogenesis of the latency phase in cutaneous leishmaniasis?

A

➝ regulatory immune response characterised by balance of Th1 and anti-inflammatory responses
➝ parasites remain present long term

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21
Q

What is a recidivans?

A

➝ A recurrence of lesions at the old ulcer site

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22
Q

What is mucocutaneous disease associated with?

A

➝ strong but inadequate inflammatory response to parasites that have metastasised to mucosa

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23
Q

What can trigger relapse in leishmaniasis?

A

➝ alteration in immune response

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24
Q

What are the three main species of schistosomiasis and what areas of the body do they affect?

A

➝ Schistosoma mansoni - hepatic and intestinal
➝ S. haematobium - urinary system
➝ S. Japonicum - hepatic

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25
Q

Describe the life cycle of schistosomiasis?

A

➝ People become exposed to the infective stage in contaminated water
➝ they get infected with cercariae
➝ the cercariae migrate through the body forming adults in the mesenteric system
➝ schistosoma haematobium forms in the vessels around the bladder
➝ they form adults, the female releases eggs which are pushed through the mucosal epithelium in the feces or urine which contaminates water and infects snails

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26
Q

How do you get cercarial dermatitis?

A

➝ Exposure to cercariae from animal or bird schistosomes

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27
Q

What type of reaction does cercarial dermatitis?

A

➝ Allergic type reaction

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28
Q

What happens to the eggs of schistosoma?

A

➝ they become organised in granulomas

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29
Q

What leads to organ damage in schistosomiasis?

A

➝ Repeated insults and tissue repair lead to fibrosis and organ damage

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30
Q

How does hepato-intestinal schistosomiasis occur?

A

➝ Infection with S. mansoni and S.Japonicum

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31
Q

What is pathology caused by in hepato-intestinal schistosomiasis?

A

➝ Immune response to the eggs

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32
Q

How does hepato-intestinal schistosomiasis occur?

A

➝ The adults are in the mesenteric vessels, the eggs are pushed by the immune response through the intestinal wall and through the mucosa

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33
Q

What happens with chronic exposure during hepato-intestinal schistosomiasis?

A

➝ fibrosis in the liver

34
Q

How do the eggs get into the urine in urinary schistosomiasis?

A

➝ adults live in the vessels around the bladder
➝ they release eggs into the vessels
➝ the eggs get pushed into the mucosa of the bladder and are excreted in the urine

35
Q

What is a common sequelae to urinary schistosomiasis?

A

➝ there is inflammation in the bladder wall related to the eggs and damage to the bladder wall which leads to cancer

36
Q

What is a symptoms of urinary schistosomiasis in endemic areas and at what age does this occur?

A

➝ haematuria

➝ adolescence

37
Q

What is onchocerciasis caused by?

A

➝ Filarial parasites

38
Q

What is onchocerciasis transmitted by?

A

➝ black flies

39
Q

Where is the female worm found in onchocerciasis?

A

➝ coiled up in fibrous nodules under the skin

40
Q

What geographical regions is onchocerciasis found in?

A

➝ Equatorial regions of africa and central and south america

41
Q

Describe the life cycle of onchocerciasis?

A

➝ The blackfly bites and transmits infectious larvae
➝ the larvae migrate under the skin and develop into adults which mate
➝ the female releases thousands of larvae called microfilariae which are taken up by the blackfly again

42
Q

What is the vector of onchocerciasis?

A

➝ Simulium

43
Q

Why does permanent scarring occur in onchocerciasis?

A

➝ Repeated episodes of inflammation to the presence of microfilariae leads to permanent damage and scarring in the skin and eyes

44
Q

Why do you give diethylcarbamazine to patients with onchocerciasis?

A

➝ The parasite downregulates the immune response

➝ the downregulation can be switched off by giving diethylcarbamazine

45
Q

What type of immune response is there to onchocerciasis?

A

➝ Strong allergic response with a lot of eosinophils that form eosinophilic abscesses

46
Q

What 4 skin diseases occur as a result of onchocerciasis?

A

➝ Acute papular onchodermatitis
➝ Chronic onchodermatitis
➝ with repeated inflammation there is damage to collagen and elastin
➝ sowda

47
Q

What 3 anterior segment eye diseases occur as a result of onchocerciasis?

A

➝ Punctate keratitis
➝ acute iridocyclitis
➝ sclerosing keratitis

48
Q

What is sclerosing keratitis?

A

➝ with repeated inflammation there is opacification of the cornea

49
Q

What is punctate keratitis?

A

➝ little opacities in the cornea

50
Q

What 2 posterior segment eye diseases occur as a result of onchocerciasis?

A

➝ Optic neuritis/atrophy - the retinal vessels are sheathed and there is a pale optic disc
➝ chorioretinopathy

51
Q

What is chorioretinopathy?

A

➝ small white spots in the eye where microfilariae are being killed

52
Q

In the acute stage of onchocerciasis what chemokines are produced?

A

➝ Strong Th2 response with the production of IL-4 and IL-5

53
Q

What does IL-4 make?

A

➝ IgE

54
Q

What does IL-5 do?

A

➝ Recruits and activates eosinophils

55
Q

In the chronic stage of onchocerciasis what happens to the immune system and what kind of a response is there?

A

➝ there is a modified Th2 response with production of IL-10 and IgG

56
Q

What 7 diseases do hard ticks cause?

A 
➝ Tick typhus
➝ viral encephalitis
➝ viral fevers
➝ viral haemorrhagic fevers
➝ tularemia
➝ tick paralysis 
➝ human babesiosis
57
Q

What 2 diseases do soft ticks cause?

A

➝ Q fever

➝ relapsing fever

58
Q

What is tick paralysis?

A

➝ progressive flaccidity due to a failure of AcH liberation in the neuromuscular junction

59
Q

What 5 types of diseases hard bodied ticks carriers of?

A

➝ rickettsial, spirochaetal, viral, bacterial and protozoan diseases

60
Q

What does a tick’s toxin cause?

A

➝ a block in the motor nerve fibres

61
Q

How are head lice spread?

A

➝ close contact, sharing of combs, brushes, hats

62
Q

What do head lice do?

A

β­’ suck blood from scalp and lay eggs on hair

63
Q

What do body lice do?

A

➝ Suck blood from body and lay eggs on clothing

64
Q

How are pubic lice different in morphology to body or head lice?

A

➝ they are broad and flat with very large stout claws

65
Q

Describe the lifecycle of the botfly?

A

➝ Midflight the fly lays eggs on a mosquito

➝ the mosquito bites an animal and the egg hatches and larvae migrate into the skin

66
Q

Why are botflies hard to extract?

A

➝ they have spines on the side of their body which anchor into tissue and make them hard to extract

67
Q

What is orbital cavitary myiasis caused by?

A

➝ cochliomyia hominivorax

68
Q

What 2 drugs are protozoa usually treated with?

A

➝ tinidazole

➝ metronidazole

69
Q

What is the advantage of tinidazole over metronidazole?

A

➝ it has a shorter regimen

70
Q

What 3 other drugs can protozoa be treated with?

A

➝ Nitazoxanide
➝ Benznidazole
➝ Heavy metals (meglumine antimoniate)

71
Q

What is Chagas disease treated with?

A

➝ Benznidazole

72
Q

What is leishmania treated with?

A

➝ heavy metals

73
Q

What 5 drugs are helminths treated with?

A 
➝ albendazole/mebendazole
➝ praziquantel
➝ ivermectin
➝ diethylcarbamazine
➝ pyrantel
74
Q

What 2 drugs are ectoparasites treated with?

A

➝ Ivermectin

➝ benzyl/malathion lotions

75
Q

What is used to treat nematodes such as schistosomiasis?

A

➝ praziquantel

76
Q

How can you control parasite infections by changing behavior?

A

➝ Education

➝ hand washing and hygiene behaviors

77
Q

How can you control parasite infections by environmental intervention?

A 
➝ Spraying of residual insecticides for household vectors
➝ mosquito nets for malaria
➝ improved housing
➝ sewage disposal and potable water
➝ drainage of swamps
78
Q

How are parasite infection in endemic areas treated and why?

A

➝ treatment must be given periodically over long periods of time because re-infections are rapid or because the treatment kills larval and not adult stages

79
Q

What is given to control soil transmitted helminth infections?

A

➝ Single dose of albendazole is given to high risk groups such as school children every 4 months

80
Q

What is given and how often to control onchocerciasis?

A

➝ A single dose of ivermectin is given to endemic communities every 6 or 12 months

81
Q

What is given and how often to control schistosomiasis?

A

➝ A single dose of praziquantel is given to endemic communities every 6 or 12 months

π“œπ‘’π’Ήπ’Ύπ’Έπ’Άπ“ π“œπ’Ύπ’Έπ“‡π‘œπ’·π’Ύπ‘œπ“π‘œπ‘”π“Ž (17 decks)

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