Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > 6- Pathogenesis of parasitic infections > Flashcards

6- Pathogenesis of parasitic infections Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
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 faeces or urine which contaminates water and infects snails

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you get cercarial dermatitis?

A

➝ Exposure to cercariae from animal or bird schistosomes

➝ Requires pre-sensitization​

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of reaction does cercarial dermatitis?

A

➝ Allergic type reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens to the eggs of Schistosoma?

A

➝ they become organised in granulomas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What leads to organ damage in schistosomiasis?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does hepato-intestinal schistosomiasis occur?

A

➝ Infection with S. mansoni and S. Japonicum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is pathology caused by in hepato-intestinal schistosomiasis?

A

➝ Immune response to the eggs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens with chronic exposure during hepato-intestinal schistosomiasis?

A

➝ fibrosis in the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

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

A

➝ haematuria- blood in urine

➝ adolescence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is onchocerciasis?

A

➝ major blinding disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is onchocerciasis caused by?

A

➝ Filarial parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is onchocerciasis transmitted by?

A

➝ blackflies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where is the female worm found in onchocerciasis?

A

➝ coiled up in fibrous nodules under the skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What geographical regions is onchocerciasis found in?

A

➝ Equatorial regions of Africa and Central and South America

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the life cycle of onchocerciasis?

A

➝ The blackfly bites and transmits L3 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the vector of onchocerciasis?

A

➝ Simulium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of immune response is there to onchocerciasis?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What can you observe clinically in onchocerciasis?

A

➝ Onchocercal nodules- female worms inside
➝ skin disease
➝ eye disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

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

A

➝ Punctate keratitis
➝ acute iridocyclitis
➝ sclerosing keratitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is sclerosing keratitis?

A

➝ with repeated inflammation there is opacification of the cornea
➝ blindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is punctate keratitis?

A

➝ little opacities in the cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

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

A

➝ Optic neuritis/atrophy

➝ chorioretinopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is chorioretinopathy?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is optic atrophy?

A

the retinal vessels are sheathed and there is a pale optic disc

32
Q

In the acute stage of onchocerciasis what chemokines are produced?

A

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

33
Q

What does IL-4 make?

A

➝ IgE

34
Q

What does IL-5 do?

A

➝ Recruits and activates eosinophils

35
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

36
Q

What 7 diseases do hard ticks cause?

A 
➝ Tick typhus
➝ viral encephalitis
➝ viral fevers
➝ viral haemorrhagic fevers
➝ tularemia
➝ tick paralysis
➝ human babesiosis
37
Q

What 2 diseases do soft ticks cause?

A

➝ Q fever

➝ relapsing fever

38
Q

What is tick paralysis?

A

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

39
Q

What 5 types of diseases hard bodied ticks (Ixodidae) carriers of?

A

➝ rickettsial, spirochaetal, viral, bacterial and protozoan diseases

40
Q

What does a tick’s toxin cause?

A

➝ a block in the motor nerve fibres

41
Q

What are soft-bodied ticks (Omithodorus) vectors of?

A

➝ endemic relapsing fever (caused by Borrelia duttoni) and Q-fever

42
Q

What disease transmitted by ticks is prevalent in the US?

A

➝ Lyme disease

➝ via Deer ticks

43
Q

What do head lice do?

A

⭢ suck blood from scalp and lay eggs on hair

44
Q

What do body lice do?

A

➝ Suck blood from body and lay eggs on clothing

45
Q

What is the prevalence of head lice and body lice?

A

➝ head lice- common

➝ body lice- uncommon

46
Q

How does head lice spread?

A

➝ easily spread by close contact

➝ sharing of combs, brushes, hats

47
Q

How does body lice spread?

A

➝ by bodily contact

➝ sharing of clothing, bedding

48
Q

What diseases are caused by transmission of body lice?

A

➝ vector diseases
➝ epidemic typhus
➝ trench fever
➝ relapsing fever

49
Q

What can cause infection with lice?

A

➝ lousiness related to sanitation
➝ crowded conditions
➝ long period without bathing or changing clothes

50
Q

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

A

➝ they are broad and flat
➝ appear crab-like
➝ mid & hind legs are stout with very large claws
➝ abdominal segments have distinct lateral lobes

51
Q

What are other names for pubic lice?

A

➝ Pthiridae

➝ crab lice

52
Q

What do pubic lice bites cause and how does it spread?

A

➝ bites cause irritation
➝ typical rash
➝ spread by close body contact- usually sex

53
Q

What do head lice do?

A

⭢ suck blood from scalp and lay eggs on hair

54
Q

What do body lice do?

A

➝ Suck blood from body and lay eggs on clothing

55
Q

Describe the lifecycle of the botfly?

A

➝ Mid-flight the fly lays eggs on a mosquito

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

56
Q

Where is Dermatobia Hominis (human botfly) common?

A

Latin America

Brazil, Ecuador

57
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

58
Q

What is orbital cavitary myiasis caused by?

A

➝ cochliomyia hominivorax

59
Q

What 2 drugs are protozoa usually treated with?

A

➝ tinidazole

➝ metronidazole (traditional)

60
Q

What is the advantage of tinidazole over metronidazole?

A

➝ it has a shorter regimen

61
Q

What 3 other drugs can protozoa be treated with?

A

➝ Nitazoxanide
➝ Benznidazole
➝ Heavy metals (meglumine antimoniate)

62
Q

What is Chagas disease treated with?

A

➝ Nitazoxanide

➝ Benznidazole

63
Q

What is leishmania treated with?

A

➝ Heavy metals (meglumine antimoniate)

64
Q

What 5 drugs are helminths treated with?

A 
➝ albendazole/mebendazole
➝ praziquantel
➝ ivermectin
➝ diethylcarbamazine
➝ pyrantel
65
Q

What 2 drugs are ectoparasites treated with?

A

➝ Ivermectin

➝ benzyl/malathion lotions

66
Q

What is used to treat nematodes such as schistosomiasis?

A

➝ praziquantel

67
Q

Why is ivermectin the ‘best’ drug?

A

➝ single dose effective against ectoparasites

68
Q

How can you control parasite infections by changing behaviour?

A

➝ Education

➝ hand washing and hygiene behaviours

69
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
70
Q

How can you reduce poverty to control parasite infections?

A

➝ micro-financing

71
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

72
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

73
Q

What is given and how often to control onchocerciasis?

A

➝ A single dose of ivermectin is given to endemic communities (mass drug administration) every 6 or 12 months

74
Q

What is given and how often to control schistosomiasis?

A

➝ A single dose of praziquantel is given to endemic communities (mass drug administration) every 6 or 12 months

75
Q

Comment on the distribution of parasites?

A

They have a worldwide distribution but are found predominantly in tropical regions among populations living in poverty

76
Q

Comment on the treatment of parasitic infections?

A

Although there are effective treatments for most parasitic infections, limited investment still means limited treatment options (NTD) and problems of drug toxicity for many infections.

77
Q

Overall, how can we control/eliminate parasite infections?

A

Poverty reduction and education interventions combined with drug treatments will control/eliminate many parasite infections.

Microbiology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions