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MMI 426 > Arthropods > Flashcards

Arthropods Flashcards

1
Q

athropods can affect human health in 4 basic wasy

A
  1. parasite disease transmission as vectors: mechanical, biological
  2. bites and envenomations
  3. tissue invasion
  4. psychological/psychiatric manifestations = entomophobia, delusion parasitoses
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2
Q

arthropods as vectors

A
  • Diptera = mosquitoes, flies, midges
  • Acarina = ticks and mites
  • Hemiptera = triatomid bugs
  • Siphonaptera = fleas
  • Anoplura = sucking lice
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3
Q

arthropods = bites

A
  • acarina
  • anoplura
  • araneae = spiders
  • chilopoda = centipedes
  • diptera
  • heimptera (bedbugs, kissing bugs, triatomid bugs)
  • siphonaptera
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4
Q

difference between bites and envenomations

A

envenomations = stinging; venomous

bites = non-venomous; inject anticoagulant saliva so they can feed on your blood = body rxn to antigenic components of saliva; not associated with dangerous venomous effects mostly

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5
Q

b=venomous arthropods

A
  • hymenoptera (ants, bees, hornets, wasps)
  • scorpions
  • other = caterpillars, spiders, millipedes, blister beetles, etc.
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6
Q

tissue invasion arthropods

A

acarina
diptera
pentastomida (tongue worms)
siphonaptera

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7
Q

siphonaptera

A
  • fleas
  • small,wingless, laterally flattened, over 2000 sp
  • survive >1 yrs even unfed
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8
Q

abnormal or exaggerated fear of arthropods or insects

A

entomophobia

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9
Q

people who think they are infested by arthropods regardless of lack of evidence

A

delusion parasitoses

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10
Q

flea cycle pyramid

A
  • 50% eggs = about 2 weeks to hatch depending on humidity
  • 35% larvae = spin cocoons within 5-20 days of hatching from eggs
  • 10% pupae = stay in cocoon for many days or weeks prior to emerging when vibrations and body heat alert it that host is near
  • 5% fleas = feed from host within few hrs of emerging from cocoon; begin to lay eggs
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11
Q

fleas can affect us in 2 major ways:

A

human exoparasites

vectors for infectious diseases

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12
Q

human exoparasites

A

red itchy bumps = host rxn to flea saliva = may get infected if scratched

  • Pulex iritans (human fleas)
  • Ctenocephalides canis/felis (dog/cat fleas)

flea dermatitis = hypersensitive hosts, hives, blisters lasting many days to weeks

most bites localized on feet and ankles

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13
Q

flea vectors for infectious diseases

A

Xenopsylla cheopis (rat flea)
plague (bacteria)
typhus (ricketsiae)
dog tapeworm (D. caninum)

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14
Q

legs of fleas

A
  • unusual adaptation
  • protein resilin pads provide energy needed to jump
  • jumps can be vertical or horizontal; reach 200 body lengths at 200g acceleration (like flying)
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15
Q

do fleas have eyes?

A

usually when they infect diurnal hosts they have well-developed eyes compared to fleas that infect nocturnal animals

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16
Q

mouthpartso ffleas

A

adapted to suck blood from host

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17
Q

compact body of fleas

A

so they can move swiftly in hairs/feathers of host

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18
Q

itch mite

A

Sarcoptes scabiei
- life span = 1-2 months
- severe itch as they burrow through superficial layers of skin
- adult female = burrows and lays eggs; two to three days to develop to develop to larvae and another 2-3 days = nymph => adult female -> mate with males

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19
Q

fecal pellets

A

more of an irritant than eggs laid by Sarcoptes scabiei

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20
Q

symptoms of Sarcoptes scabiei

A

very severe itchy rash (red lines), blisters

scratching kills mites but may cause bacterial superinfection

NOTE: patient may be asymptomatic for 2-6 wks but after exposure can still spread infection to others

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21
Q

T or F. You should avoid direct skin contact with person infected with scabies

A

T! at least after 8 hours after treatment is complete because even treated patient can disseminate infection

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22
Q

where can Sarcoptes scabiei be found?

A

mostly skin folds; epidermis (in between pts or interdigital spaces, buttocks, axilla, groin, etc.)

red line = blister formed at end of burrow = where you can usually find a female scabies

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23
Q

Norwegian scabies

A
  • some hosts such as elderly or diabetics with neurological conditions = don’t feel itch = don’t scratch = 1000s of mites instead of 10 -15
  • extremely contagious = high # of mites
  • scale, crusted skin = very painful and uncomfortable
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24
Q

diagnosis of Scabies

A

microscopy of skin scrapings
preferably at the end of burrows to catch female

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25
Q

Cimex sp.

A

bed bugs
- known since Greece
- feed on blood (warm blooded animals and humans) at night every 5-10 days
- poor eyesight so may use CO2 (that we release) to move along
- temporary parasite = because only visit humans when need to feed
- may live up to 18 mos without feeding
- eggs in dark protected places = furniture cracks, behind pictures, wallpapers
- notorious hitchhikers and travel on objects such as clothing, books, bgs, furniture, spreading infestation to new locations

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26
Q

larval form of bedbugs

A

incstars

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27
Q

thin when hungry but expand as they feed

A

bed bugs

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28
Q

how many larval stages do bedbugs have?

A

five
feeding on blood is required to develop to next stage

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29
Q

T or F. Bed bugs have wings

A

F! They have wing pads but through evolution lost their wings

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30
Q

hunger folds of bed bugs

A

11
will unfold when feeding = balloons up
but when hungry - flat = slips through crevices

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31
Q

unique feeding apparatus of bedbugs

A
  • head fitted with tube-like structure = rostrum = folds underneath head and long body when not in use; when in use = unfolds to downward piercing position
  • mandible = inside rostrum = serrated edges ; cut into host skin
  • maxillae = behind mandible; once skin breached these search for blood vessels
  • Cibarian pump = head of bug; initiate sudden gentle suction to have blood flow to bedbug; ensures constant blood flow
  • salivary duct = anticoag saliva and anesthetic to vessels to ensure bite is painless and host not disturbed
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32
Q

how to get rid of bedbugs?

A

Vacuum your house thoroughly, including cracks and crevices.
Dispose of the vacuum cleaner bag right away (in a sealed plastic bag to contain the bugs)

Wash clothes and other objects in hot water (at least 50°C).
Dry the clothes and other items in a clothes dryer on the high heat setting for 20 minutes.
You can also put pillows and stuffed toys in the dryer (even without washing)

Hire a professional exterminator.

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33
Q

clinical manifestations of bedbugs

A
  • little/no rcn to itchy rash/anaphylaxis
  • bite marks = may be single but usually multiple and linear = ‘breakfast, lunch, and dinner”
  • may transmit hep B and Chagas disease (still disputed; so bedbug bites mainly a nuisance than a serious infection)
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34
Q

Most common species of bedbugs

A

Cymex lectularius

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35
Q

rustic brownish spots

A

characteristic of bed bugs infestation
- dont just look for bedbugs; look for these too

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36
Q

myiasis

A

infestation of live humans and vertebrate animals with dipterous larvae which feed o host’s dead or living tissue, as well as liquid body substances or ingested food

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37
Q

specific myiasis

A

arthropods behave as obligatory tissue parasites
- life in tissue of hosts = needed for complete cycle

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38
Q

semispecific myiasis

A

eggs or larvae in decaying flesh or vegetable matter/ morbid tissues
- not necessary for cycle; could be replaced by environmental development

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39
Q

ACCIDENTAL MYAISIS

A

eggs accidentally fall in excrements, decaying organic matter or foods

40
Q

nosocomial myiasis

A

happens more often during neglect in hospitals

41
Q

site of invasion for myasisis

A

cutaneous
ophthalmic
nasal
aural
- development of larvae in the skin, eyes, nose, ear

42
Q

uncommon forms of myiasis

A

intestinal
urogenital
lung

43
Q

Dermatopbia hominis

A

cutaneous myiasis

44
Q

Gasterophilus sp

A

cutaneous, rarely gastric myiasis

45
Q

Hypoderma bovis

A

subcutaneous, ocular myiasis

46
Q

Ostrus ovis

A

nasopharyngeal, ocular myiasis

47
Q

order of lice

A

Pthiraptera

48
Q

sucking lice suborder

A

anoplura

49
Q

lice (pthiraptera)

A
  • ectoparasites of mammals and birds
  • small, flattened insects that are blood sucking; mouthparts usually retracted iwthing head and modified for piercing and sucking
  • segmented body = head, thorax, abdomen, 3 prs of jointed legs, pair of antennae, NEVER wings
  • order is divided into suborder = chewing lice = Ischnocera and Amblycera from sucking lice Anoplura
50
Q

where are lice usually found?

A

preferred host = info on host and site of infestation of host is an important aid to ID

51
Q

species of lice most important to public health

A

body louse, head louse, and crab louse

52
Q

symptoms of lice

A

intense irritation
has a role in carrying epidemic typhus, relapsing fever, and trench fever

53
Q

three main soecies of sucking lice

A

Pediculus humanus (body louse)

Pediculus capitis (head louse)

Pthirus pubis (crab or genital louse)

54
Q

head louse life cycle

A

gradual metamorphosis; eggs laid on hair shaft

6-7d = young louse hatches
first moult = 2 d after hatching
second mpoult = d after hatching
third moult = 10d after hatching

2 adult louse M & F; F slightly larger; F reproduce

F lays eggs 2d after mating; 4-8 eggs for the next 16d - then dies

55
Q

development of head loiuse

A

50-300 eggs/female

from egg to adult approx takes 1month

56
Q

the stage that hatches from eggs is the first _________; what does this resemble?

A

nymph; resembles adult and feeds with them

57
Q

lice nymphs

A

they resemble adults

molt through three stages and final moult produce sexually mature adults

adults similar except for genital structures
- M has sclerotized gen structures
- F has sclerotized gonopods

58
Q

where is life cycle of lice happening?

A

entire life cycle spent on host and spread between hosts occurs by lice crawling when hosts come into contact

59
Q

lice as human exoparasites

A

human pediculosis = papules (small lumps), blisters, skin thickening, and pigmentation

60
Q

Vagabond’s disease

A

human pediculosis
- disease occur in ppl who are street ppl, down and out ppl, and ppl who have bad hygiene habits

61
Q

lice as vectors

A

louse-borne typhus
= Ricketsjae, Borreliae, Bartonella (trench fever)
= travel over 20 cm/min

62
Q

lice travel speed

A

over 20cm/min

63
Q

what are the eggs of human head louse referred to

A

Pediculus capitis = nits

64
Q

body louse Pediculus humanus infects…

A

clothing of humans esp. those unable to change clothing

65
Q

P. humanus transmits the following:

A

Rickettsia prowazekii
Bartonella
Borrelia

66
Q

R. prowazekii

A

louse borne or epidemic typhus

67
Q

Bartonella

A

bacteria
causes trench fever

68
Q

Bartonella

A

epidemic relapsing fever

69
Q

T or F. P. capitis transmits pathogens

A

F!

70
Q

T or F. P. capitis is commonly found infesting school children

A

T! head louse infests children … NOT body louse

71
Q

how can process of lice detection be enhanced?

A

UV lamp
white specs = nits

72
Q

describe nits of head/body louse

A
  • laid singly; 0.8 mm in length and 0.3 mm across
  • cap or perculum at one end and attach to host hair by cement secreted by female at time of lay
  • head louse lay eggs at base of hair
  • body louse lay e ggs in folds of clothing at seams
  • eggs hatch between 6-14d if kept at body temp
  • 40C eggs will die in couple of days
  • maintained at 20C eggs developed but nyph dies in that egg
  • exposure to 8C kills it in 7d
  • when ready to hatch = nymph pushes off the operculum and forces out of the egg
73
Q

how does the lab report lice?

A

P.humanis/capitis ; head and body louse bc can’t differentiate

74
Q

features of crab louse

A
  • smaller than P. humanis
  • body wide and abdomen narrower and short
  • head = blunt at tip and small eyes
  • mid and hind legs are stout; large claws
  • movement slow and deliberate like crabs
  • found infesting hairs of armpits, bear, pubic and perianal regions of both sees
  • irritation can be intense
75
Q

distribution of crab louse

A

worldwide like P. humanis but is NOT known to transmit any diseases

76
Q

nits of crab louse

A
  • never found on clothing
  • smaller than head/body louse
    0 attach to hair of host with larger amt of cement
  • nymph hatches from egg after an incubation period of 7-8 d; three nymphal stages than the adult hatch about 13-17d; adult lives for ~month
  • rare found on scalp; infants seen with crab louse in scalp = head to head transmission due to close contact instead of sexual contact
  • tends to spread among ppl living in bad conditions
77
Q

T or F. Crab louse likes to hand of hair of the host

A

T

78
Q

prevention of body lice

A
  • spread most commonly by direct contact with an infested person or their clothing
  • bathe regularly
  • change properly laundered clothes at least once a week
  • launder infested clothing at least once a week
  • machine wash infested clothing and bedding using the host water (130C) and high heat drying cycle
  • clothing and items not washable can be dry-cleaned OR sealed in plastic bag & stored for 2 weeks
  • do not share clothing, beds, bedding, and towels used by an infested person
  • fumigation or dusting with chemical insecticides sometimes is necessary to control and prevent the spread of body lice for certain diseases
79
Q

prevention of head lice

A
  • historically shaving
  • avoid head-to-head contact during play and other activity
  • do not share clothing such as hats, scarves ,etc.
  • do not share combs, brushes, towels; disinfect combs and brushes used by an infested person by soaking them in hot water (130C) for 5-10mins
  • do not lie in beds, couches, pillows, etc that have been in recent contact w infested perosn
  • same as body louse = high heat drying cycle and host washing machine settings
80
Q

prevention of pubic louse

A
  • all sexual contacts of infested person should be examined => treay
  • sexual contact bw infested persons and their partners should be avoided until al have been examined and treated
  • machine wash and dry clothing worn and bedding used by infested person in hot (130C) water; high heat drying OR sealed in plastic bag and stored for 2 weeks
  • do not share clothing, etc.
  • do not use fumigant sprays or fogs = not necessary to control pubic lice and can be toxic if inhaled or absorbed through skin
  • persons with pubic lice should be examinend and treated for other STDs
81
Q

treatment of pediculosis

A
  • improved hygiene and access to regular changes of clean clothes = only treatment needed for body lice
  • OTC and prescription meds are available for head and pubic lice infestations
    > Pyrethrins
    > Permethrin
  • use prescribed meds with caution
  • head infestations can be dealt with combing with a special fine metal toothed comb paying special attention to hair at back of neck and ears
  • no known insecticide removes nits though some may kill them
82
Q

what is a tick?

A

obligate hematophagous ectoparasite = have to eat a blood meal

arachnid(Acari); not an insect

not an insect; no segmented body, eyes, ears, etc

more closely related to mites and spiders

sense hosts via CO2

cannot jump or burrow into skin

divided into hard ticks (Ixodidae) and soft ticks (Argasidae)

83
Q

soft ticks

A
  • Argasidae
  • look a bit like a raisin
  • some psinuy outer surface, some leathery outer cuticles
  • transmit some diseases
  • bed bug- like life cycle = immature life stages and tend to feed at night time
84
Q

hard ticks

A
  • Ixodidae
  • scutum = shield-shaped structure on dorsal surface
    > in females = less than half of dorsal surface, males = entire dorsal surface
  • males only can take a small blood meal
  • females = gros quite large
85
Q

unfed vs fully fed female

A

can be up to 100x size of an unfed female

if full = ready to drop to ground and lay 3000-5000 eggs and then die

86
Q

structure ticks used for feeding

A

denticles structure like teeth = gluey compound = stick to surface

middle of structure = hollow = used like a straw

87
Q

tick removal procedure

A
  • grasp tick as close to skin as possible
  • dont sequeeze; dont grab main mody of tick
  • pull off in one steady motion
  • examine area for attached mouthparts
  • wash area with soap and water
  • save tick for surveillance
  • there are some tick removal compounds but tweezers better *
88
Q

life cycle of hard ticks

A

molt between three life cycles

  • egg
  • larva (6 legs); attach to host; feed; drop off
  • nymph (8 legs); attach to different host; drop off
  • adult (8 legs, female or male); third host; F feed, mate and feed to repletion and M only take small meals
  • ticks can overwinter and live up to 3 yrs
  • 3-host and 1-host lifecycle ticks in AB
    > 1-host tick = moose tick; can complete entire life cycle on one host
    >3-host tick greatly increases a tick’s chances of acquiring and transmitting a pathogen
89
Q

T or F. 3-host tick greatly increases a tick’s chances of acquiring and transmitting a pathogen

A

T!
some pathogens can stick with a tick for its entire life cycle, while some have to be re-acquired to be transmittable

90
Q

tick-borne diseases

A
  • ticks = major vector of many human and animal pathogens
  • due climate change, arthropod diseases are forecast to increase as vector ticks spread geographically
  • bacterial: Lyme disease, Rocky ountain spotted fever, anaplasmosis, etc.
  • protozoan: babesiosis
  • viral: colorado tick fever virus
  • syndrome: tick paralysis Alpha Gal
91
Q

Borrelia burgdorferi sensu stricto

A

original pathogen and main type found in NA (Lyme Disease)
- B. burgdorferi sensu lato genospecies (eg. B. mayonii) here in NA

intracellular spirochete
interesting genome = 1MB linear chromosome with 15+ mix of linear or circular plasmids

92
Q

how is Lyme disease transmitted?

A
  • B. burgdorgeri is transferred into host via tick saliva
  • takes 24 hrs for bacteria to move from saliva to host (so have window of time to remove tick before infection)
  • cannot be transmitted transovarially in tick but transstadial transmission does occur
    > larval, nymph, or adults must acquire the pathogen during feeding on an infected host
  • B. burgdorferi is maintain in an area by reservoir hosts, typically mice here in NA
93
Q

major vector of B. burgdorferi in NA

A

three-host hard tick = Ixodes scapularis

94
Q

Rocky Mountain Spotted fever

A

Rickettsia rickettsii
- intracellular cb
- transmitted by Dermacentor sp.
- ticks are vector and reservoir (transovarial transmission)
- lots of vector species in AB but reports of RMSF rare

95
Q

AlphaGal

A
  • (non-primate, vertebrate) red meat allergy caused by immune response to alphagalactose
  • Amblyomma americanum bite thought to be major source
    > but other ticks also suspected
96
Q
A

MMI 426 (20 decks)

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