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Amy Somerville > INF2 - F. ECTOPARASITES-COVERED > Flashcards

INF2 - F. ECTOPARASITES-COVERED Flashcards

1
Q

what are ectoparasites

A
  • ticks and lice
  • they live externally ie - on skin
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2
Q

symptoms of ticks and lice

A
  • itching
  • scratching
  • bites
  • soreness (secondary infection?)
  • infestation NOT infection but
  • parasites are hosts for transmitted pathogens and disease
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3
Q

what phylum are ticks, mites, fleas and lice

A

phylum arthropoda

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4
Q

what class are fleas and lice

A

class insecta

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5
Q

what class are ticks and mites

A

class arachnida

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6
Q

what do ticks, mites, fleas and lice do

A
  • blood sucking parasites to gain their energy
  • live on skin
  • host specific - human
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7
Q

where are ticks mostly distributed

A
  • woodland
  • deers are the most endemic natural host for ticks
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8
Q

ticks

A
  • adults, larvae, nymphs climb tall grass and shrubs
  • they quest and wait for something warm blooded to pass
  • attach to host
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9
Q

signs of ticks

A
  • move up body
  • warm sweaty places
  • exposed limbs (top of legs, top of arms, buttocks) and neck
  • no itching
  • visual examination is only way to see
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10
Q

treatment of ticks

A
  • no pharmacological treatment
  • physical removal
    tweezers or tick card (grab neck and twist out)
    don’t squeeze or crush body as it will vomit in bloodstream
    don’t leave head behind
    don’t burn off or use other noxious mean
    keep tick for +ve identification
    ok if removed within 24 hrs of attachment
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11
Q

consequences of tick bite

A
  • UK and Europe: Lyme disease, Tick-borne encephalitis
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12
Q

Lyme disease

A
  • bacterial disease carried by tick
  • spirochetes borrelia burgdorfi

symptoms
- bulls eye rash (Erythema migrans: not hot, itchy or scaly - red ring with a red centre)
- flu-like symptoms
- incubation 2-100 days
- 14% of world population may have had Lyme disease

treatment
- oral antibiotic: doxycycline

prevention
- cover up
- topical insecticide

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13
Q

tick borne encephalitis

A

-viral disease carried by tick
- flavivirus
- infects brain

symptoms
- fever then mild flu-like then no symptoms ‘recovered’
- then neurological symptoms, high fever
- headache - encephalitis, meningitis - paralyses
- over 3 weeks
- death possible within 7 days of neurological symptoms

  • vaccination: FSME-Immun and Encepur
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14
Q

Lice (nits)

A
  • infestation: pediculosis
  • cling to hair shafts
  • crawl
  • travel quickly
  • highly contagious
  • persistent >1 if untreated
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15
Q

what are the 3 types of lice

A
  1. head lice
  2. body lice
  3. pubic lice (crabs)
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16
Q

headlice

A

symptoms
- itching of scalp
- difficulty sleeping
- scratching - secondary bacterial infections on neck?
- raised bumps on neck
- girls at higher risk than boys: long hair, sharing brushes

diagnosis
- visual inspection
- wet comb and paper so lice stick

socioeconomic impact
- school days lost
- workdays lost

notifiable disease

17
Q

treatment of lice

A
  • P medicines
  • 8-12 hours contact time

Dimeticone lotion 4%
- doesn’t kill live eggs just kills parental organism (adult) so need to reapply to wait for eggs to hatch

Benzyl alcohol emulsion 25%
- doesn’t kill live eggs

Malathion lotion 0.5%
- kills adult and partially kills eggs

Lindane shampoo 1%
- outdated
- can cause neurological damage/death
- no used in UK

18
Q

how does dimeticone work

A
  • silicone based (like oil)
  • forms water impervious coat if silicone on lice
  • suffocated lice
19
Q

how does benzyl alcohol work

A
  • suffocation
20
Q

how does malathion work

A
  • organophosphorous anticholinesterase
  • neurological toxin as:
    acts on nervous system of animal
    irreversibly bind to and blocks cholinesterase so stops synaptic activity
    promotes cholinergic neurotransmission (ACh used as NT)
    post-ganglionic neuronal excitation
    continues muscle excitation and contraction and dies
21
Q

contraindications of malathion

A
  • low toxicity to man
  • only with repeated exposure and overdose will be toxic as will be absorbed through scalp and can be irritating
  • ingestion and metabolism to toxic malaoxon therefore
  • oxidation to malaoxon also occurs by chlorination of water
  • therefore don’t eat or drink
  • no more than 4 consecutive applications
  • anti cholinesterase activates parasympathetic nervous system
  • promotes muscarinic transmission
  • neuromuscular, promotes nicotinic transmission at
    skeletal muscle
  • CNS, promotes cholinergic neurotransmission
22
Q

effects of malathion/malaoxon poisoning

A

muscarinic (parasympathetic) effects:
- miosis (pupillary constriction)
- salivation
- sweating
- bradycardia
- increased bowel movements
- urinary incontinence

nicotinic (SkM) effects:
- fasciculation (twitching) due to spontaneous release of ACh
- paralysis due too depolarising neuromuscular block

CNS effects:
- anxiety
- restlessness
- dizziness

ALL DUE TO HEIGHTENED ACH ACTION

23
Q

how does lindane work

A
  • gamma-hexachlorocyclohexane
  • ion channel antagonist
  • neurological toxin
  • binds to and inhibits GABAa chloride channel complex
  • acts at picrotoxin site
  • delta subunit

brain releases GABA reduce excitability of brain
if blocked becomes more excited and may go into epileptic episodes

BUT
- GABAa is ubiquitous in Animalia
- so interferes with mammalian central neurotransmission
- GABAa antileptic, dampens neuronal activity
- so can cause seizures and convulsions
- definite no

24
Q

prophylaxis for lice

A
  • wet comb and shampoo/hair conditioner
  • insecticide (pyrethroids)
  • tee oil (alternative to conditioner)
25
Q

symptoms of public lice

A
  • pubic, armpit, chest, leg, facial hair
  • itching
  • inflammation from scratching - secondary infection?
  • black powder in underwear (discarded bodies of dead lice)
  • tiny blood spots on underwear (crushed dead lice)

diagnosis
- visual detection

26
Q

how is crabs spread

A
  • sexual contact
  • condoms don’t protect
  • non-sexual via fomites
  • children: indicator of sexual abuse
27
Q

symptoms of body lice

A
  • pruritis
  • skin discolouration/thickening
  • secondary bacterial infection
  • red rash

diagnosis
- visual detection

28
Q

treatment of body and public lice

A
  • insecticides applied initially once to whole body
  • Permethrin - iron channel agonist
  • Malathion
  • applied for 12 hours
  • ineffective ovicides so repeat after 7 days to kill newly hatched lice to prevent reinfestation
  • to prevent re infestation: hot wash
29
Q

what bacterial diseases can body lice transmit

A
  • louse-borne relapsing fever (yellow fever)
  • trench fever
  • bubonic plague

Amy Somerville (70 decks)

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