Brainscape's Knowledge GenomeTM

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


See full index

MD3002 Pathology > Protozoal and Helminth Infections of the GI tract > Flashcards

Protozoal and Helminth Infections of the GI tract Flashcards

1
Q

What do rates of intestinal protozoa and helminth infections in a population generally reflect?

A

Hygiene / sanitation standards

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

How are new infections brought about?

A
  • Contact with faecal-derived material

- Usually acquired through ingestion of contaminated food or water

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

What do infections generally present with?

A

Acute to chronic diarrhoea and inflammation

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

What bacterial disease can lie dormant in the gallbladder?

A

Salmonella

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

What protozoal infections affect the SI?

A
  • Giardia lamblia

- Cryptosporidium parvum

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

What protozoal infections affect the LI?

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

What protozoal infection is a frequent cause of travellers’ diarrhoea?

A

Giardia Lamblia

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

What are the 2 stages of giardia lamblia life cycle?

A 
Trophozoite 
- Flagellated and bi-nucleated 
- Lives in upper part of SI
- Adheres to brush border of epithelial cells 
Cyst
- Formed when trophozoite forms resistant wall
- Passes out in stools 
- Can survive for several weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the pathogenesis of G. lamblia

A
  • Present in the duodenum, jejunum and upper ileum
  • Attaches to the mucosa via ventral sucker
  • Does not penetrate surface
  • Causes damage to the mucosa and villous atrophy
  • Leads to malabsorption of food, esp. fats and fat soluble vitamins
  • May swim up the bile duct to gall bladder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the clinical manifestations of G. lamlia infection?

A
  • MIld infections are asymptomatic
  • Diarrhoea is usually self-limiting (7-10 days)
  • Chronic diarrhoea presents in immunocompromised patients
  • Stools are characteristically foul-smelling and fatty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What led to a massive increase in cryptosporidium parvum infections in the past?

A

AIDS epidemic (oppurtunistic infection)

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

How is C. parvum transmitted and what is the reservoir?

A
  • Usually through faecally-contaminated drinking water
  • Animal reservoir (usually cattle)
  • As few as 10 oocysts required for infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the life cycle of C. parvum

A
  • Host ingests oocysts with sporozoites
  • Sporozoites attach to host cells and invade intestinal epithelium
  • Division to form merozoites which re-infect cells can cause auto-infection
  • Sexual phase and produce fertilized oocysts
  • Mature oocyst then released in faeces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 different types of C. parvum cysts?

A
  • Thin walled stay in host

- Thick walled are released into environment

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

Describe the pathogenesis of C. parvum

A
  • Enters cells of the microvillus border of SI
  • Remains within vacuole of epithelial cell
  • May multiply to give large numbers of prgeny, especially in immunocompromised hosts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How much faeces can be produced as a result of C. parvum infection?

A

25 litres of watery faeces / day

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

What does Entamoeba histolytica cause?

A

Emebic dysentary

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

How can E. histolytica be transmitted?

A
  • Contaminated food or water

- Anal sexual activity

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

What can amoebic ulcers cause?

A

After mucosal invasion, cysts invade RBCs giving rise to amoebic colitis

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

Describe the pathogenesis of E. histolytica?

A
  • Adheres to epithelium and acute inflammatory cells
  • Resists host humoral and cell mediated immune defence mechanisms
  • Produces hydrolytic enzymes, proteinases, collagenase, elastase
  • Produces protein that lyses neutrophils, the contents of which are toxin to the host
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the clinical manifestation of E. hostolytica?

A
  • Small localised superficial ulcers leading to mild diarrohoea
  • Entire colonic mucosa may become deeply ulcerated leading to severe amoebic dysentery
  • Complications include intestinal perfusion
  • Trophozoites may spread to the liver, and other organs
  • Rarely, abscesses spread to overlying skin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the differences between bacillary and amoebic dysentery?

A
  • Bacillary have many PMN in stool few in entamoeba
  • Eosinophils abscent in bacillary present in amoebic
  • Many bacilli in stool few amoebae in stool
  • Blood/mucus in both
23
Q

What antibiotic is very affective against protozoal infection?

A

Metronidazole

24
Q

What are the ingrediants in ORS?

A
  • Glucose 13.6g/L
  • NaCl 2.6g/L
  • KCl 1.5g/L
  • Trisodium citrate dihydrate 2.9g/L
25
Q

What are the features of roundworms (nematodes)?

A
  • Bisexual

- Cylindrical

26
Q

What are the features of tapeworms (Cestodes)?

A
  • Elongated flatworms
  • Segmented
  • Hermaphrodite
27
Q

What are the features of flukes (Trematodes)?

A
  • Leaf-shaped flatworms
  • Mainly hermaphrodites
  • Rare in humans
28
Q

Name some helminthic organisms which infect the GI tract

A
  • Strongyloides stercoralis (pinworm / threadworm)
  • Trichuris trichiura (whipworm)
  • Ascaris lumbricoides (giant roundworm)
  • Enterobius vermicularis (pinworm / threadworm)
  • Ancylostoma duodenale (hookworm)
  • Taenia solium (tapeworm)
29
Q

What are the most clinically relevant intestinal worms?

A

Nematodes

30
Q

How are nematodes often transmitted?

A
  • Often soil-trnsmitted
  • Swallowing infective eggs
  • Active skin penetration by larvae and systemic migration through lung to intestine (strongyloides stercoralis)
31
Q

How are nematode infections diagnosed?

A

Stool microscopy

32
Q

What are the features of Strongyloides stercoralis?

A
  • Pinworm

- Cresnt shaped

33
Q

How does S. stercoralis affect the GI tract?

A
  • Disrupts small intestinal mucosa
  • Villous atrophy
  • Marked loss of elasticity of intestinal wall
34
Q

What are the clinical manifestations of S. stercoralis?

A
  • Dysentery (persistent in immunocompromised hosts)
  • Dehydration
  • Malabsorption syndrome
  • Anal pruritis
  • Association with appendictis
35
Q

How long can Trichuris trichiura live in the gut for?

A

Over 3 years

36
Q

What does T. trichiura look like?

A

Whipworm

37
Q

How is T. trichiura transmitted?

A

Acquired through eggs on vegetables

38
Q

What is the appearence of Ascaris lumbricoides?

A
  • Giant roundworm

- Large thick white worm approx. 20 - 30 cm

39
Q

How many eggs to A. lumbricoides produce?

A

approx 20,000 eggs / day from 65 days after infection

40
Q

How long does A. lumbricoides live in the gut for?

A

Adult lives in gut for 2 years

41
Q

How prevelant is A. lumbricoides infection?

A
  • 1 million clinical cases per year

- 20,000 deaths

42
Q

What are the clinical manifestations of A. lumbricoides infection?

A
  • Allergic reaction in sensitised people
  • Digestive upsets
  • Protein/energy malnutrition
  • Intestinal blockages
  • Worm may invade mouth, nose etc.
43
Q

What does Enterobius vermicularis look like?

A
  • Threadworm

- Small cylindrical nematodes < 1 cm

44
Q

How does E. vermicularis infect humans?

A
  • Female migrates to anus at night to lay approx. 10,000 eggs, which may develop to infective stage within hours
45
Q

What is the clinical manifestation of E. vermicularis infection?

A
  • Intense itching
  • Secondary bacterial infection
  • Mild catarrhal inflammation and diarrhoea
  • Slight eosinophilia
46
Q

What does ancylostoma duodenale look like?

A

Hookworm

47
Q

How can ancyclostoma duodenale be transmitted?

A

Walking barefoot in infected areas

48
Q

What are the affects of A. duodenale / what does it do?

A
  • Attaches to SI, suck blood and protein, often present in huge numbers
  • Cause hypochromic anaemia
  • Blood loss 0.03ml/day/worm (often 500-1000 worms)
49
Q

What kind of worm is Taenia solium?

A

Tapeworm

50
Q

How large can Taenia solium grow?

A

7m

51
Q

Where does Taenia solium reside?

A

The large intestine

52
Q

How is T. solium usually transmitted?

A

Ingesting worms or eggs in undercooked pork

53
Q

What part of T. solium attaches to the intestine?

A

Scolex

54
Q

What are the diffficulties around antiprotozoal and antihelminthic agents?

A
  • Large variety of species to treat
  • Complexities of their life cycles
  • Differences in their metabolic pathways
  • Drugs active against protozoa are inactive against helminths

MD3002 Pathology (19 decks)

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