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PHAY10: Communicating Science & Practice > Clinical - Parasitology > Flashcards

Clinical - Parasitology Flashcards

1
Q

What is a parasite?

A

Animal living in or on the body of another, which gains advantage from the host.

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2
Q

What are ECTO parasites?
Give 2 examples.

A

Parasites found on the surface of the host (like the skin)

Examples - lice + mites

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3
Q

What are ENDO parasites?
Give 2 examples.

A

Parasites found in the body of the host

Examples = worms, protozoa

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4
Q

How are body lice spread?

A

They are found on fabrics and pass onto the body to feed on blood, then go back onto fabrics (especially seams) until they want to feed again.

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5
Q

How are body lice spread?

A

Clothing-clothing contact
Skin contact

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6
Q

What is the lifespan of body lice outside of the host?

A

5-7 days

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7
Q

What are symptoms of a body lice infection?

A
  • Intense itching (due to the injection of saliva into the skin)
  • Rash + red bumps
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8
Q

What 2 things can happen is body lice infections are not treated?

A
  1. Parasites can cause thickening or discolouration of the skin (especially groin/waist area)
  2. Secondary infections
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9
Q

How would you treat body lice infections?

A
  1. Antihistamines = for itchiness
    • Insecticides - used if there are lots of lice that can be found on clothing/bedding and/or skin
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10
Q

4 hygiene tips for lice infection

A
  1. Bathe/shower regularly
  2. Wash clothes at ≥ 50C
  3. Store contaminated clothing in a closed containers for > 2 weeks (so they have no blood to feed upon)
  4. Vacuum mattresses
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11
Q

Describe the life cycle of (pubic) lice

A

Lifespan = 1-3 months
They go through 3 forms in their lifetime:
1. Egg (nit)
2. Nymph = immature louse that hatches from eggs
3. Adult lice

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12
Q

Symptoms of pubic lice

A
  • Itching in affected areas
  • Inflammation or irritation in the affected areas caused by scratching.
  • Black powder in underwear.
  • Blue coloured spots on skin where lice are living (e.g. thighs, lower abdomen)
  • Tiny blood spots on underwear or skin.
  • Nits/eggs stuck to hairs
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13
Q

Name 2 drug treatments used for pubic lice

A
  1. Permethrin 5% cream
  2. Malation 0.5% liquid
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14
Q

What do head lice do on humans?

A

Cling to hair shaft with their claws + feed on blood from the scalp.

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15
Q

How long do head lice live for?

A

1-2 months

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16
Q

What is the difference between nits and lice?

A

Nits are empty white eggshells that stick strongly to hair shaft  NOT a sign of current infection + not removed by treatment.

Lice are the parasite released from eggs that feed on humans and cause infections.

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17
Q

What is the main issue with a head lice infection?

A

Most people do NOT have symptoms. If they do, they may have an itchy scalp as an allergic response from the lice’s saliva (NOT from biting the scalp).

It can take ~ 3 months for an itch to develop

Lice are not washed off with normal shampoo

Itch can remain after lice are removed

Not everyone with lice will have itching (takes 1000s of bites to cause an itch)

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18
Q

What other conditions should be checked when diagnosing head lice?

A
  1. Dandruff
  2. Seborrheic dermatitis
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19
Q

Explain the wet comb method

A
  1. Wash hair as normal
  2. Put in lots of conditioner
  3. Comb out tangles
  4. Use (metal) detection comb in the roots of the hair, touch the scalp and draw down to the tips.
  5. Comb all parts of the scalp.
  6. Check for lice after each comb through.
  7. Rinse out conditioner.
  8. Repeat.

Takes 10-15 mins per head (depends on hair length)

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20
Q

Explain the dry hair method

A
  1. Untangle hair with a comb.
  2. Using a detection comb, comb through each section of hair 3-4 times.
  3. Look for lice each time.
  4. Trap lice with the thumb to avoid lice being repelled by static electricity as comb is withdrawn from the hair.
  5. Continue until the full head is covered.

Tip: hold white paper/tissue under the hair to catch the lice.

21
Q

When would family and friends need to use treatment for head lice?

A

ONLY IF THEY HAVE LIVE LICE!
Do NOT use prophylactically = ineffective + resistance issues

22
Q

Give 3 examples of physical insecticides (Product + Drug)

A
  1. Hedrin = dimeticone 4%
  2. Full Marks solution = Isopropyl myristate + cyclomethicone solution
  3. Vamousse
    = Isopropyl myristate + isopropyl alcohol aerosol
23
Q

Give an example of a chemical insecticide (Product + Drug)

A

Derbac-M
= Malathion 0.5% aqueous liquid

24
Q

What are 2 examples of physical insecticides?

A
  1. Bug Buster
    = Wet combing
  2. Nitview - LEDComb
25
Q

Why might treatment using insecticides fail?

A
  • Poor technique
  • Inadequate quantity of product used
  • No current infection
  • No repeat applications done (in timely manner or at all)
  • Resistance to insecticides
  • Short contact time of product on the scalp
  • Re-infection by close contact
  • Not treating all infected members of the family
26
Q

Which insecticides can be used by pregnant/breastfeeding women?

A

Wet combing or dimeticone 4% lotion

27
Q

Where are scabies infections more likely to be found?

A

Densely populated areas (e.g. institutional settings)

28
Q

How are scabies mites spread?

A
  1. Close physical contact = classical infection
  2. From infested fabrics (RARE) = crusted infection
29
Q

What is Norwegian/crusted scabies?

A

Scabies present in immunocompromised patients causing more severe symptoms
[May be more contagious = MUST REFER]

30
Q

What is the life cycle of a scabies mite?

A
  1. Female tunnels itself into the epidermis
  2. Eggs are deposited along the burrow
  3. Larvae hatch in a few days + make NEW burrows
  4. Eggs into adult takes 10 days
  5. Mites die after 4-6 weeks
31
Q

What do scabies mites do to humans?

A

Female mite burrows into the skin to lay eggs, and faecal pellets left in the skin can cause local hypersensitivity → releases inflammatory mediators = allergic reactions + itching.

32
Q

What are the symptoms of scabies?

A
  1. Itching and rashes (can continue weeks after infection has passed)
  2. Presence of burrows
33
Q

When is scabies worse and why?

A

Night time or after a hot bath

This is when mites release faecal pellets into the skin

34
Q

Differential diagnosis for scabies includes:

A
  1. Allergic contact dermatitis
  2. Dermatitis herpetiformis
  3. Body lice
  4. Pompholyx
  5. Insect bites
35
Q

Why may it be hard to diagnose scabies infections?

A

Diagnostic burrows can be hard to see due to scratching – skin may be red and inflamed.

36
Q

REFERRAL criterIa for scabies:

A

Babies + children < 2 years
Infected skin
Failed treatment
Unclear diagnosis
Genital scabies
Norwegian/crusted scabies

37
Q

What drug treatment can be used for scabies?

A
  1. Permethrin 5% cream (Lyclear)
  2. Malation 0.5% (Derbac-M)
    3.Benzyl benzoate (Ascabiol)
38
Q

Recommendations for symptomatic relief

A
  1. Calamine lotion
  2. Eurax cream
  3. Antihistamines (sedating)
    Hydrocortisone 1% cream
39
Q

When would ivermectin need to be prescribed?
How does it work?

A

If a patient has treatment-resistant or crusted scabies.

Shuts down mite’s nervous system.

40
Q

Non-drug treatment advice for scabies:

A
  1. Clean ALL bed linen at high temperatures (≥ 50C) after first treatment as mites live for ~ 1 day after.
  2. If you cannot wash certain items, put them in a plastic bag for at least 72 hours → mites will die.
  3. There is no evidence that a hot bath will open burrows.
  4. Make sure skin is always clean, cool and dry.
  5. Apply insecticide preparation all over the body with cotton wool or sponge.
  6. Reapply to hands if they are washed.
  7. Scabicide penetrates the skin to kill mites + lay eggs in the basal layer of the epidermis.
  8. 2nd application of products are used one week after the 1st.
  9. Treat ALL family members and partners – preferably on the same day. Other household members may be infected but asymptomatic as it takes weeks for itch to develop.
  10. Avoid close contact with ANYONE, even those at home until everyone is treated.
  11. DO NOT GO TO SCHOOL/WORK BEFORE TREATMENT IS USED.
  12. Children + adults can go back to school/work AFTER 1st treatment is complete.

For crusted scabies: Thoroughly clean the floors in the house + vacuum carpets and furniture

41
Q

How are threadworms spread?

A

Transmitted mostly via faecal-oral route, also through retroinfection and inhalation.

42
Q

How do threadworms cause infection?

A
  1. Threadworm eggs may be lodged under fingernails and ingested.
  2. Duodenal fluids break eggs down to release larvae into the intestines.
  3. After worms mate, the female moves to the anus (at night) and lays eggs on the perianal area.
43
Q

Why do worms cause night time itching?

A

Worms will know it’s night time due to ↓ body temp + gut motility, so carry out their life cycle at that time.

44
Q

What is the stick tape test?

A

Stick some tape onto the anus either before bathing OR after defecation and before wiping (in the morning), tape is checked under a microscope for presence of worms.

45
Q

Differential diagnosis for threadworm includes:

A
  1. Skin conditions
  2. Haemorrhoids
  3. Other work infections
46
Q

REFERRAL criteria for theradworm:

A
  1. Fever + bedwetting or pain on urination
  2. Vaginal discharge (if eggs laid in vaginal area)
  3. Vomiting
  4. Severe diarrhoea
  5. Unexplained weight loss
  6. Recently travelled abroad (could be other worms)
  7. Excoriation (constant skin picking/scratching)
  8. Secondary bacterial infection
47
Q

How long should non-drug management be used for?

A

≥ 2 weeks if anthelminthics are used

≥ 6 weeks if no drug treatment is used

48
Q

What drug is used for scabies?
How does it work?

A

Mebendazole = inhibits worm’s uptake of glucose

49
Q

Non-drug treatment advice for threadworm:

A
  1. Wash pyjamas, bed linen, towels and toys → eggs can survive 2 weeks without host
  2. Vacuum + damp-dust the home (throw out clothes after use)
  3. Wear close-fitting underwear at night
  4. Shower every morning (not bath)
  5. Wash hands + scrub underneath the nails first thing in the morning, before eating and after using the toilet
  6. Do NOT bite fingers or put hands in the mouth
  7. Cut fingernails short
  8. Avoid sharing towels
  9. Cover food in the home
  10. Rinse toothbrushes well before using, and store them in a closed cupboard

PHAY10: Communicating Science & Practice (19 decks)

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