Protozoal and Helminthic infections Flashcards
1
Q
How to treat acute amoebiasis
A
Metronidazole
2
Q
How to treat chronic amoebiasis
A
Diloxanide furoate
3
Q
How does metronidazole act
A
- Under anaerobic conditions, it generates toxic radicals that damage bacterial and protozoal DNA
- Penetrates well into tissue
4
Q
What is metronidazole active against
A
- E histolytica
- G lamblia
5
Q
Side effects of metronidazole
A
- Metallic taste
- Acute nauseous reaction with alcohol
6
Q
What is diloxanide furoate
A
Luminal amoebicide
7
Q
Side effects of diloxanide furoate
A
- Flatulence
- Itchiness
- Hives
8
Q
Describe paromomycin
A
- Aminoglycoside
- Kills amoebic cystic stage
- Not absorbed from GI tract
9
Q
Side effects of paromomycin
A
- Abdo cramps
- Diarrhoea
- Heartburn
- Nausea
- Vomiting
10
Q
Give examples of vectors
A
- Flies= onchocerciasis
- Crysops= guinea worm
- Snails= capillaria
11
Q
Give examples where inflammation is the main pathogenic mechanism
A
- Filariasis
- Onchocerciasis
- Toxocariasis
- Enterobius
12
Q
What can acute lymphodaema progress to
A
Elephantiasis
13
Q
Trichuiris clinical features
A
- Vague abdo symptoms
- Trichiuris dysentery syndrome
- Growth retardation
- Intellectual compromise (due to micronutrient deficiency and mucosal integrity)
14
Q
Give example of space occupying lesions
A
- Cysticercosis causing CSF obstruction
- Ascaris causing intestinal obstruction
15
Q
Clinical manifestations of S stercoralis
A
- Erythema migras
- Dysentery
- Dehydration
- Anal pruritis
- Malabsorption syndrome
- Associated with appendicitis
16
Q
How to treat helminths that compete for nutrients
A
- Reduce worm burden
- Support nutrition
17
Q
How to treat space occupying lesions
A
- Surgery
- Decompression
18
Q
How to treat cestodes
A
Praziquantel
19
Q
How to treat cysticercosis
A
- Anti-epileptic drugs
- Anti-helmithic
- Steroids
20
Q
How to treat nematodes
A
- Albendazole (most effective)
- Levamisole and piperazine
21
Q
Action of praziquantel
A
- Increases Ca2+ permeability of membranes depolarising them
- May interfere with purine synthesis
22
Q
What is praziquantel used for
A
- Hydatid disease
- Cysticercosis
- Schistosomiasis
- Clonorchis, Fascioliasis and Paragnomiasis
23
Q
Physiology of praziquantel
A
- Significant first pass effect
- Excreted in kidneys
- Short half life
24
Q
Side effects of praziquantel
A
- Dizziness, headaches, drowsiness etc
- Abdo cramps and diarrhoea
- Urticaria, rash and pruritis
- Interacts with rifampicin, carbamazine, phenytoin
25
What is Albendazole used to treat
- Nematode infections (trichuiriasis, filariasis)
- Some protozoa (giardia)
- Cestode (Hydatid, neurocysticercosis)
26
Mode of action of albendazole
- Binds to colchicine sensitive receptor or tubulin
- Prevents polymerisation into microtubules
- Impaired glucose uptake and depleted glycogen stores
- Degenerative changes appear in worm
27
Side effects of albendazole
- May be teratogenic (concentrated in semen)
- Persistent sore throat
- Headaches, dizziness
- Acute liver failure
- Aplastic anaemia and marrow suppression
28
Action of piperazine
Agonist activity against the gamma butyric acid receptor paralysing muscular activity
29
Physiology of piperazine
- Orally active
- Metabolism in liver
- Variable half life
30
What is piperazine used to treat
- Ascariasis
| - Enterobius
31
Side effects of piperazine
- GI upset
- Hypersensitivity
- Dizziness
32
What is pyrantel used to treat
- Hookworms
| - Roundworms
33
Action of pyrantel
Causes depolarising muscular blockade
34
Physiology of pyrantel
- Poorly absorbed, providing selective toxicity
- Excreted unchanged in faeces
- Antagonistic with piperazine
35
When to avoid pyrantel
- Pregnancy
| - Heavy worm load (can cause intestinal obstruction)
36
Action of levamisole
Nicotinic ACh receptor antagonist
37
When to use levamisole
-Ascariasis
-Mixed ascaris hookworm infection
(-Don't use in pregnancy)
38
Side effects of levamisole
- Abdo pain
- Nausea
- Vomiting
39
Action of diethyl carbamazine
Inhibits arachidonic acid, making parasites more susceptible to immune attack
40
When to use diethyl carbamazine
Filaria infection
41
What is use of diethyl carbamazine associated with
- Increase in inflammation (Mazzotti reaction)
| - Loss of site in onchocerciasis
42
Action of ivermectin
Binds glutamate-gated chloride increases in the permeability of membrane to Cl- ions with hyper polarisation of nerve/muscle cell resulting in paralysis and death of parasite (either directly or by causing the worms to starve)
43
What is ivermectin used against
- Fliarial worms
- Lice
- Scabies
- Bed bugs
- Lymphatic filariasis
- Onchocerciasis
44
Risks of ivermectin
- Not for use in children <5 or breast feeding mothers
- Complicated by CNS depression
- Increased risk of absorption past the BBB of HIV protease inhibitors, CCBs and glucocorticoids
45
Action of niclosamide
Inhibits glucose uptake, oxidative phosphorylation and anaerobic mechanisms
46
When is niclosamide used
Tape worm infections
47
Side effects of niclosamide
- Dizziness
- Skin rashes
- Drowsiness
- Perianal itching
48
Prevention and control of intestinal helminths
- Vector control for filariasis
- Meat inspection for cysticercosis
- Sanitation and hygiene for intestinal nematodes
