Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

DTMH > Lice, mites and fleas > Flashcards

Lice, mites and fleas Flashcards

(93 cards)

Start Studying
1
Q

What are the order and suborder of lice?

A

Order - pthiroptera
Suborder - anoplura

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

What are the species and subspecies of lice?

A

Pediculus humanus
- humanus
- capitis
Pediculus pubis

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

What is subspecies known as the the body louse?

A

Pediculus humanus humanus

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

Describe the general external morphology of pediculus humanus humanus

A

Small (2-4mm), pale, beige
Wingless
Dorsoventrally flattened
Eyes = simple ocelli
Mouthparts adapted for piercing and sucking (tube-like haustellum with tiny teeth for gripping during feeding)

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

Describe the female external morphology of pediculus humanus humanus

A

Short, thick tibia with small thumb-like pike on inner apex side and curved claw on tarsus
Spine and claw used to grip host hair/clothing
Bifurcated abdomen for gripping fibers of cloth during egg laying

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

Describe the male external morphology of pediculus humanus humanus

A

Smaller
Camouflaged
Longer foreleg claws
Rounded abdomens

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

Describe the life cycle of pediculus humanus humanus

A

Hemimetabolous life cycle 17-19d

Egg -> 3 nymphal stages -> adult

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

Discuss the behaviour of pediculus humanus humanus

A

Both sexes take blood meals
Live in host clothing and feed off body
Slow feeders
Defecate during feeding

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

Discuss the eggs/nits of pediculus humanus humanus

A

6-9 eggs per day in seams of clothes
Occasionally lay eggs on body hairs (pubic, perineal, axillary)
Oval, white, 1mm long eggs
Hatch after 7-10d
Do not survive >4/52

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

When do nymph instars of pediculus humanus humanus occur?

A

After blood meal

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

How soon do pediculus humanus humanus adults die without a blood meal?

A

Within 4-2d

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the medical importance of pediculus humanus humanus?

A

Most cases have itchiness only (intermittent, at night)
Small, red papules w/ red punctum from scratching
7d post bite small weal/papules develop

Longstanding infection
- rough, thickened skin appearance with fine furfuraceous scaling (“Vagabond disease”)
- secondary infection with impetigo

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

What are pediculus humanus humanus a vector for?

A

Typhus
Trench
Relapsing fever

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which organism causes typhus?

A

Rickettsia prowazekii

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

Which organism causes trench?

A

Bartonella quintana

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

What was bartonella quintana previously known as?

A

Rochalimoea quintana

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which organism causes relapsing fever?

A

Borrelia recurrentis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is pediculus humanus humanus transmitted?

A

Female cannot transmit transovarially
Transmission via rubbing infected material (faeces, body fluids, louse hemolymph) into skin wound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is bartonella quintana transmitted to lice?

A

Transmitted via faeces and body fluids and ingested and multiplies in the midgut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is rickettsia prowazekii transmitted to lice?

A

Ingested with blood meal into the gut where it multiplies in the epithelial cells, causing them to rupture and release the rickettsiae into gut content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Is rickettsia prowazekii pathogenic to lice?

A

Yes, die within 7-20d

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Is bartonella quintana pathogenic to lice?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How is borrelia recurrentis transmitted to lice?

A

After ingestion, spirochetes develop in the lice hemolymph
Transmission to humans via the crushed louse’s hemolymph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Is borrelia recurrentis pathogenic to lice?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Discuss control of pediculus humanus humanus
Ironing of clothes Washing of clothes >60 degrees Malathion and carbaryl to treat as a 0.5% alcohol lotion (kills all louse stages) 10% DDT dust with talcum powder of body and underclothes
26
What can you offer if pediculus humanus humanus is resistant to insecticides?
2% temephos 5% carbaryl 1% propoxur 2% pyrethrum
27
Discuss the external morphology of pediculus humanus capitis
Very similar to humanus humanus Live on scalp Can interbreed with humanus humanus
28
Discuss the life cycle of pediculus humanus capitis
Takes 17-25d Similar to humanus humanus Egg at first is cemented in the angle between hair and scalp 3 nymphal stages Live and feed on scalp 10-20 lice per individual
29
How are pediculus humanus capitis spread?
Close contact Sharing of clothes, hairbrushes, headgear
30
What is the medical importance of pediculus humanus capitis?
Itchiness in the early stages that causes restlessness, irritability in children due to scratching Scratching -> secondary infections eg impetigo Can transmit rickettsia and spirochetes in lab conditions
31
Discuss the control of pediculus humanus capitis
Head lice campaign - education - regular inspection of school children - regular home inspection Treatment
32
Discuss treatment of pediculus humanus capitis
Malathion and carbaryl as 0.5% alcohol lotion, apply a few drops and massage into entire scalp esp per-auricular and suboccipital region Louse comb
33
Discuss the external morphology of pthirus pubis
Narrow head with 6 segmented antennae Lateral eyes Slightly longer body than broad Dorsoventrally flattened 3 pairs of legs - 1st are slender - each ends with a powerful claw Lateral protrusions that end in cluster of setae on many of the abdominal segments
34
Discuss the lice cycle of pthirus pubis
Similar to humanus Egg -> 3 nymphal stages -> adult 22-27d Egg incubation 7-8d Several eggs laid on the same hair
35
What is the medical importance of pthirus pubis?
Mostly affects pubic and axilla regions Can affect eyebrows and eyelashes in children (only in adults if heavily infested)
36
How does eyelid infestation of pthirus pubis appear?
Yellowish encrustation with nits attached to eyelashes and skin Eye edema if severe
37
How is pthirus pubis spread and does it transmit disease?
Spread by close contact (sex, bed sharing) Does not transmit disease
38
Discuss the control of pthirus pubis
1. HCH (must be repeated as not ovicidal) 2. 1% malathion and carbaryl lotion for 12 hours then washed off 3. Golden eye ointment
39
What is HCH?
Hexachlorocyclohexane
40
What is the issue with 1% malathion and carbaryl lotion for pthirus pubis?
Cannot use on the eyelids
41
Discuss the external morphology of mites
Small arachnids Head, thorax and abdomen fused in unsegmented body Part of head region including mouthparts is attached to anterior of body by a moveable hinge Integument may be membraneous OR thickened into plates on dorsal and ventral surfaces
42
How did habit of mites feeding develop?
Developed from free-living forms inhabiting nests of small animals and feeding on decayed organic matter
43
What is the habitat of mites?
Terrestrial and aquatic Certain species are endo/ectoparasities Ectoparasites of skin, mucous membranes and feathers
44
Discuss the life cycle of mites
Egg -> larvae -> nymph -> adult Relatively large eggs deposited on soil/host skin 1-2 eggs laid at each oviposition
45
What is the difference between mite larvae and adults?
Larvae - 3 pairs of legs Adults - 4 pairs of legs
46
What are the significant mites?
Sarcoptes scabiei Sarcoptes mites
47
Describe the external morphology of sarcoptes scabiei
Hemispherical Short walking legs 1st 2 pairs of legs have ambulacral process used in burrowing 3rd and 4th leg pairs bear long setae Females larger than males
48
How is sarcoptes mites transmitted?
Direct physical contact Clothing Linen Can survive up to 48h outside of host
49
Discuss the burrowing of sarcoptes mites
Burrow into host skin within 2.5 minutes Extend burrow up to 4mm per day Fertilized female lays eggs in burrows Small vesicles and papules form at entry site (intensely itchy especially at night)
50
What is the most common infection site of sarcoptes mites?
Between fingers Knee flexors Elbow flexors Groin Breasts Shoulder blades Waist Genitals
51
What are the histological changes seen in scabies?
Epidermis - acute eczematous tissue reaction - acanthosis - spongiotic edema - exocytosis - formation of intraepidermal vesicles Dermis - prominent perivascular inflammatory cell infiltrate - extravasation of erythrocytes Stratum corneum - mite burrows Old lesions - excoriation - parakeratosis
52
Discuss diagnosis of scabies
Mite/egg in skin scrapings Skin scraping site important as mite usually burrows a few mm away from lesion 3-20 mites per patient
53
What is norwegian scabies?
Infestation of thousands of mites Characterised by extensive, heavily crusted skin lesions Usually in immunocompromised or disabled individuals
54
Discuss treatment of scabies
Tetmosol soap Benzyl benzoate 2 applications Alpha BHC/sulphur in ointment
55
Discuss the external morphology of demodex
Minute Obligate parasite Stub-like legs Elongated opisthosoma
56
What are the 2 common species of demodex?
D. folliculorum D. brevis
57
Where do the 2 common demodex species occur?
D. folliculorum - hair follicles D. brevis - sebaceous glands
58
What are demodex associated with?
Acne rosacea
59
Discuss the treatment of demodex infection
Tetmosol Ascabiol Beta-naphtol Sulphur in ointment
60
What are dermatophagoides ubiquitous in?
House dust Bedding Furniture Feed on human scales
61
What can dermatophagoides cause due to the allergen they produce?
Asthma Severe dermatosis
62
Discuss control of dermatophagoides
Frequent dust removal Avoidance of down pilows Household insecticide
63
What is the latin for fleas?
Siphonaptera
64
Discuss the external morphology of fleas
Head, mouthparts, thorax, legs, abdomen and external genitalia Laterally compressed Wingless Blood sucking ectoparasites
65
Discuss the head of fleas
Compressed like the body Divided by deep groove containing the antennae into frons and occiput Frontal portion of head carries mouthparts
66
Discuss the mouthparts of fleas
Consist of sucking tube which is enclosed in a sheath formed by pair of labial palpi at rest Broad maxillary serrated stilettos near base
67
Discuss the ocelli of fleas
Ocelli and NOT facetted eyes Some have enlarged Some have reduced/absent
68
Discuss antenna of fleas
Sense organ Used by males to capture and hold female during copulation
69
Discuss the thorax of fleas
Compact thorax - prothorax - mesothorax - metathorax (highly developed to sustain jumping mechanism)
70
Discuss the pronotum of fleas
Pronotum lies immediately behind head At posterior margin is comb of spine-like processes called pronotal ctenidium
71
Discuss the mesonotum of fleas
Simple arched palate
72
Discuss the abdomen of fleas
10 segments made up of plates/sclerites Apical edge of tergite 7 are antepygidial bristles Tergite 9 has pygidium (pincushion structure) Tergite 8/9 sacculated spermatheca on females that have shape unique to species
73
Discuss male genitalia of fleas
Claspers Moveable portions Non-moveable portions Manubrium
74
Discuss legs of fleas
Number and length of bristles important for taxonomy Variation indicates lines of evolution
75
Discuss the life cycle of fleas
Egg ->larvae -> pupae -> adult 30-75 days Oviposition occurs in host nest (larval food) 3-18 large, glistening white, rounded eggs deposited in 1 laying Eggs are not attached to host Take 2-14 days to hatch Larvae are active, slender, segmented with segmentally arranged bristles and biting mouthparts Larvae enter quiscent stage after active feeding period and spin cocoon of silk and sand grains Pupa can remain in cocoon until vibrations indicate presence of possible host Adult fleas only feed on blood
76
How can female fleas lay fertilised eggs 2 months after copulation?
Store sperm in the spermatheca and release them as eggs ripen
77
What is the primary reaction to flea bites?
Allergic (flea saliva)
78
What do immune person's have with flea bites?
Evanescent erythema with central hemorrhagic punctum, non-itchy
79
Which diseases do fleas transmit?
Plague Tularemia Murine typhus Salmonella Myxomatosis Trypanosomiasis Nematodes Cestodes
80
What is the sandflea?
Tunga penetrans (smallest known flea) Cause tungiasis
81
What is the external morphology of tunga penetrans?
Reddish maroon with pointed head to penetrate host skin
82
Which part of the female tunga penetrans is visible on the skin surface after burrowing?
Posterior segments of abdomen
83
What is the common site for tunga penetrans lesion?
Feet Mild itch, slight pain which worsens as flea enlarges
84
Discuss treatment of tungiasis
Remove flea with needle/excision Antibiotics if secondary infection
85
What advice would you give to prevent tungiasis?
Wear boots Never sit on infested ground
86
What is the name of the stick tight flea?
Echidnophaga gallinacean Dogs, cats, rats, birds, humans Feeds continuously on host blood
87
Which flea is suspected in the spread of plague in earlier times?
Pulex irritant
88
Which flea is the most abundant flea in tropical and subtropical regions?
Xenopsylla cheopis Common parasite of synanthropic rats Associated with plague
89
What is the principle plague carrier in South Africa?
Xenopsylla brasiliensis
90
Which fleas transmit sylvatic plague?
X. philoxera X. piriei
91
What are the common cat and dog fleas?
Ctenocephalides canis Ctenocephalis felis Names are illogical as in SA they infest the opposite animal more
92
Can common cat and dog fleas transmit plague?
Not efficient Can transmit intestinal worms
93
Discuss flea control
Vioform and hydrocortison topical application Repellants Disinfect animals Regular vacuuming

DTMH (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions