Transcript Infestations and Bites

ADL- Cirujales,MD
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1. Discuss common arthropods that can
infest the human body.
2. Identify cutaneous reactions and systemic
manifestations that occur with infestations
and bites.
3. Relate the life-cycle of commonly
identified
arthropods
to
the
clinical
presentation and management of the
disease.
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4. Identify the diagnostic tools or procedure
for the different disease condition.
5. Enumerate important health teachings that
can be incorporated in the community and
clinical setting.
ARACHNIDA
CHILOPODA
Acarina (Scabies)
Aranea (Brown Recluse
Spider)
DIPLOPODA
INSECTA
Anoplura (Pediculosis)
Hemiptera (Bedbugs)
Family Sarcoptidae
Class Arachnida
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Obligate human parasite
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Oval in shape
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Pearl-like, translucent, white
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Adult F mite 0.4x0.3mm
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Eyeless
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4 short, stubby legs
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Cannot fly or jump
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Worldwide
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All ages
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All races
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Socioeconomic status
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Epidemic or endemic
scabies in institutions
“It has been well established that close
personal contact is a prime route of
transmission.”
“…the equally high prevalence in children
attests that casual contact or sharing of
objects among children and family members
is also sufficient to transmit the disease.”
Fitzpatrick’s Dermatology in General Medicine 8 th edition
“ Mites are also prevalent in the personal
environment of normal scabies person.”
“In one study, live mites were recovered from
dust samples taken from bedroom floors,
overstuffed chairs and coaches in every
patient’s dwelling.”
Fitzpatrick’s Dermatology in General Medicine 8th edition
F mite forms burrow
Lay 2-3 eggs/day
Eggs hatch (4d;10d)
Live burrow to mature on the skin surface
M and F mite copulate
M mite falls off
gravid F burrows
Hypersensitivity Reaction
immediate reaction
delayed type
1st infestation
sensitization to S.scabiei
4-6 weeks
pruritus
Reinfestation
pruritus within 24H
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Pruritic papular lesions
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Intraepidermal burrows
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Secondary changes
-excoriations
-LSC
-PIH
-secondary infection
by Staph aureus
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Dull, red nodules
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+/- pruritus
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Scrotum, penis vulva
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Immunocompromised,
debilitated, patients w/
neurologic D/O
Crusts, scales, mites
Face, scalp
Nails- psoriasis-like
scaling, distorted
Tips of fingers swollen
and crusted
Severe fissuring and
scaling of genitalia &
buttocks
Rub a black felt-tip marker
across the affected area
Wipe excess ink with an
alcohol pad
Burrow would appear darker
than the surrounding skin
Identification of the burrow:
india ink or gentian violet
Drop mineral oil over the
burrow
Scrape off burrow with
curette or no. 15 blade
Microscope slide
Microscopy
Microscopic identification of the ff:
1. S. scabiei mites
2. eggs
3. fecal pellets (Scybala)
Highest yield in identifying is in typical
burrows:
1. finger webs
2. flexor aspect of the wrists
3. penis
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Located stratum
corneum
F mite with eggs in the
blind end of the
burrow
Spongiosis (epidermal
edema)
Eosinophilic infiltrates
(dermis)
1. Treat infested individual and close physical
contact (including sexual partners) at the
same time whether or not symptoms are
present.
2. Scabicide + fomite control
3. Second application a week after initial tx.
1.
2.
Permethrin 5% cream
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Lindane 1% lotion or
cream
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2.
4.
5.
Recommended Regimen
Crotamiton 10%
Sulfur 2-10% in
petrolatum
Benzyl Benzoate w/
sulfiram
Sulfram 25%
Ivermectin 0.8%
Alternative Regimens
Ivermectin
-200ug/kg single dose
-2 to 3 doses separated by 1 to 2 wks
(heavy infestation; immunocompromised
state)
-Epidemic and endemic scabies
-Not approved by US FDA
-C/I: infants, young children, pregnant and
lactating women
1. Post-scabetic itching
2. Secondary Bacterial Infection
3. Scabietic nodules
- IL Triamcinolone 5-10 mg/mlinto each
lession is effective
- repeat every 2 weeks if necessary
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All clothing, pillow cases, towels, bedding
used during the previous week should be
washed in hot water and dried at high heat
Nonwashables should be dry-cleaned, ironed,
put in clothes dryer w/o washing or stored in
a sealed plastic bag in a warm area for 2
weeks
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Floors, carpets, upholstery (home & car), play
areas, furniture should be carefully vacuumed
Fumigation not recommended
Pets do not need to be tx bec they do not
harbor the human scabies mite
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Loxosceles reclusa
Fiddle-back spider
Yellow, tan or brown
10-15mm long
Leg span 25 mm
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South Central United
States
Shy, nocturnal
Non-aggressive
arachnid
Lives in dark areas like
woodpiles, under rocks
or in dark corners of
attics, garages or
basements
Major cause of necrotic
arachnidism in the US
Humans come in contact with spider accidentally
Bite frequently goes unnoticed
6-8 hours later, local vasospasm
(localized, pain, stinging and burning)
12-24H later, systemic symptoms
(fever, chills, nausea, vomiting, weakness, joint and muscle pain)
Tissue necrosis occur D/T
SPHINGOMYELINASE D
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Cutaneous loxoscelism
Systemic loxoscelism
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Localized hive-like
reaction, minimal
redness & swelling
Cyanotic color
followed by expanding
necrosis
Most severe reaction
in fatty areas- thighs,
abdomen & buttocks
DERMONECROSIS
may leave an ulcer that
takes months and years
to heal
Neck-upper airway
obstruction
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Histology depends on the time biopsy was
taken
Early in the course – (+) neutrophils; (+)
“mummified” coagulative necrosis of the
epidermis, adnexae & dermis
Vasculitis in larger vessels
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Ecthyma Gangrenosum
Necrotizing Vasculitis
Necrotizing Fascitis
Pyoderma Gangrenosum
Polyarteritis Nodosa
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Supportive care
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Mild, localized reaction- rest, ice, elevation
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Necrotic skin – local wound and ulcer care
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Antibiotics
Tetanus toxoid
Dapsone 50-100mg/day is helpful in preventing
severe necrosis
Pediculosis Humanus Capitis
(Head Louse)
Pediculosis Humanus Humanus
(body, clothing louse)
Phthirus Pubis
(pubis, crab louse)
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Flattened
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Wingless
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3 pair of legs that
terminate in sharp
claws used to grasp
and hold
Obligate human
parasite
Blood meal q 4-6H
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3-12 y/o
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F>M
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Rare in AfricanAmerican
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Direct head to head contact
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Indirect contact
◦ Can be easily dislodged by air movements, blowdryers, combs and towels
◦ Passively transferred to fabric facilitating new
infestation
F louse lay 5-10 eggs/day
Eggs hatch (10 days)
Larvae/nymphs/instars
3 stages of dev’l
Full maturation day 14
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Nits within 4mm of scalp
suggest active
infestation
Newly-laid or viable
eggs are tan to brown
Non-viable eggs are
clear, white or light in
color
Presence of adult lice
confirms active
infestation
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Incubation of 4-6 wks
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◦ Pruritus
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Carriers
◦ Asymptomatic despite
infestation
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Papular urticaria on the
neck
Eczema, excoriations,
LSC ( occipital scalp)
Infection
Post occipital
lymphadenopathy
Small white hair “beads”
hair casts, hair lacquer, hair gels, dandruff
Scalp pruritus
AD, Impetigo, LSC
No infestations
Delusions of Parasitosis
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(+) DETECTION OF LICE
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Louse comb increases chances of finding lice
EYE or MICROSCOPY
Nits
0.5mm, oval, whitish eggs
Nonviable nits
Absence of embryo or operculum
Louse
Insect with 6 legs; 1-2mm length;
wingless; translucent, grayish white
body that is red when engorged with
blood
Topically applied
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Permethrin
Malathion
Pyrethrin
Piperonyl
Butoxide
Variable ovicidal activity
Pt’s compliance
Resistance
Potential fomite infestation
Oral
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Ivermectin 200ug/kg
Recommendation:
Repeat tx after 1 week
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Fine combing of hair with nit comb
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Wet combing
 Increases yield by prying the adult lice from the hair
follicle
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Occlusion and Suffocation
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Shaving one’s head to avoid infestation
 6th century BC when priests and wealthy Egyptians
shaved their hair and wore wigs
 Routine head shaving in military service
WHO – read 24H after application otherwise
mortality rates are overestimated
Headlice have the ability to “resurrect” from a
state of seeming death in which resp and
motor fxn appear to have ceased.
Less dependent on continuous nervous control
of respiration and circulation.
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Pediculosis Humanus Humanus
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2-4 mm; larger than head louse
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Attaches to body hair to feed
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Survive w/o blood meals up to 3 days
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Risk factors: poverty, war, natural disasters,
refugee-camp populations
Body lice transmit many infectious agents while
feeding:
- Bartonella Quintana (trench fever and
endocarditis)
- Rickettsia Prowazekii ( louse-borne relapsing
fever)
F lay eggs (270-300 ova)
Nits
(ova w/ chitinous case)
Incubate for 8-10 days
Life span: 18 days
Nymphs mature to
adults in 14 days
Papular urticaria
Changes secondary to rubbing and scratching
(excoriations, eczema, LSC, infection, PIH)
* scabies, pediculosis capitis and pulex irritans
(human flea) can coexist
(+) lice and nits in clothing seams
(+) lice grab on body hairs to feed
Atopic dermatitis
Contact dermatitis
Scabies
Cutaneous drug reaction
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Decontamination of clothing and bedding
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Delousing
◦ Pyrethrin
◦ Permethrin
◦ Malathion
Two types:
1. Cimex lectularius – temperate climate
2. Cimex hemipterus – tropical climate
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Flat, oval body
Retroverted mouthparts for
blood meals
Breed through traumatic
insemination
◦ Male punctures the female and
deposit sperm into her body
cavity
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Hide in cracks and crevices
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Infest bats and birds
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Suspected vectors for Chaga’s disease and
Hepatitis B
Can survive for 1 year without feeding but
usually seek a blood meal q5-10 days
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Nocturnal feeder
Attracted to the warmth
and carbon dioxide
production of their victim
Complete their meal in a
minute then return to
hiding
Spread in clothing &
baggage of travelers,
secondhand mattresses &
laundry
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Painless
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Usually overlooked
unless large numbers
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Multiple and grouped
in a linear fashion
Raw of 3 bedbug bite
is referred to as
breakfast, lunch and
dinner
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Wheals and papules
with small hemorrhagic
punctum at the center
Bullous reactions to
sensitized individual
Hypersensitivity to the
reaction have been
reported
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Drug Eruptions
Ecthyma
Insect Bites
Pemphigus Herpetiformis
Scabies
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Symptomatic tx of bites
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Local wound care
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Elimination of bird’s nest and bat roosts
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Cracks and crevices in the house should be
eliminated and treated with insecticide
Frequent retreatment may be necessary
“SCIENTIA MAXIME CUM VIRTUTE”
Knowledge is best with virtue