5.3 Biliogy of Parasites Flashcards

1
Q

What are the two types of parasites?

A

Protozoa (unicellular) and Helminths (multicellular)

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

How are protozoa classified and give an example of each

A
By motlity 
Flagellate: Giardia 
Pseudopods: entemoeba histolytica 
Ciliates: Balantidium coli 
Coccidians: cryptosoridium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are Helminths classified and give an example

A

Flatworms

  • Trematodes: flukes
  • Cestodes: tapeworm

Roundworms (nematodes)

  • Blood tissue: Wuchereria boncrofti (elephantitis)
  • Intestinal: PInworm, whipworm, hookworm, strongyloides stercoralis, ascaris lumbricodes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define definitive host

A

parasite matures into adult form and undergoes sexual reproduction

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

Define intermediate host

A

parasite development occurs but parasite does not reach sexual maturity

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

define paratenic or transport host

A

parasite remains alive and infective but does not undergo any development

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

define incidental or dead end host

A

intermediate host that generally does not allow transmission to a definitive host

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

define host sensitivity

A

range of different hosts in which a parasite can mature

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

What is the process of parasitic disease in general>

A

Gain entry to the host (exogenous or endogenous)
Replicate/disseminate (intra or extracellular)
Cause damage to the host
Spread to a new victim

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

What factors affect infection, spread, replication and damage

A

Size

  • Protozoa complete lifecycle in humans an usually have low infective dose
  • Helminths severity usually related to size

Tissue tropism

Means of evading immune response

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

What are the general consequences of parasitic infection to the host?

A
Nutritional stress 
Mechanical or physical damage 
secondary infections 
toxicity 
immunopatholgical reactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the lifecycle of giardia?

A

Exposure to stomach acids causes the release of four trophozoites
TZ colonise in small intestine
TZ undergo rapid asexual reproduction
Encystation occurs as transit through large intestine

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

What are the symptoms of giardia?

A
Asymptomatic 
Chronic diarrhoea 
Epigastric pain 
Nausea and vomiting 
Malabsorption 
Weight loss 
Symptoms typically 6-15 days after exposure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the pathophysiology of giardia?

A

Flattening of the villi and inflammation of mucus
Direct damage to intestinal brush border
Alteration of absorption
Alteration of small intestine function
Induction of a host immune response

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

What is the treatment for giardia?

A

Metronidazole

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

How does entamoeba cause infection?

A

Cysts and TZ passed in feces
Mature cysts ingested
excystation in the small intestine
trophozite replication in the large intestine
The TZ invade the intestinal wall causing invasive infection (dysentery, colitis, appendicitis)

17
Q

How does cryptosporidium cause infection?

A

Thick walled oocyst exits host
Contamination of food and water with oocysts
Thick walled oocyst ingested by host

18
Q

What are the symptoms of crytposporodium infection?

A

In normal adults - gastroenteritis
Immunosuppressed: cholera like illness, chronic diarrhoea illness, intermittent diarrhoea illness, transient diarrhoea illness

19
Q

How do you treat cryptospordium?

A

In most people rehydration but Nitazoxanide if needed

20
Q

what are the severe forms of malaria?

A

Plasmodium falciparum and Plasmodium knowlesi

21
Q

What are the clinical features of malaria infection?

A

Rigors, fevers, sweats
headaches, arthralgia, myalgia

Severe forms: cerebral, aciodsis, renal failure, anaemia, hypoglycaemia, acute respiratory distress syndrome

22
Q

How do flatworms cause infection?

A

Eggs in feces passed into the environment
Cattle and pigs become infected
oncospheres hatch, penetrate intestinal wall and into circulation and musculature
Humans eat raw or undercooked affected meat