stings, bites, and bugs Flashcards
T. cruzi causes_________
T. cruzi causes American trypanosomiais
T. brucei causes
T. brucei causes African trypanosmiaisis
american trypanosomiasis =
American Trypanosomiasis=Chagas disease
where is Chagas disease endemic?
Central and South America
Test question: how is chagas disease transmitted?
Transmission of T. cruzi through infected reduviid bugs and occasionally infected blood
what doe Chagas disease affect in body?
Serious systemic disease that primarily affects the autonomic nervous system, heart and GI tract
what is Romana sign of chagas disease?
Romana sign- edema of the palpebral and periocular tissue due to entry through the conjunctiva
what is the unique feature about the life cycle of t. cruzi?
infected bug bites human, defecates and depostis T. cruzi trypomastigotes.
symptoms of acute phase of Chaga’s disease?
Localized erythema ,swelling regional lymphadenopathy (chagoma)
_ROMANA sign - _Painless edema of palpebrae occurs in 80% of cases infected this route
Fever, malaise, anorexia, edema of face and lower extremities
when does the chronic phase of chagas disease occur?
what are the cardiac manifesations of the chronic phase?
what are the GI manifestations of the chronic phase?
- *Occurs many years to decades later**
- *Cardiac manifestations: **Cardiac failure, arrythmias, heartblock
- *Gastrointestinal manifestations: **Megacolon, Megaesophagus
which two drugs are used to treat chagas disease?
Nifurtimox: acute phase parasitologic cure 50% of the time
Benzimidazole; acute phase more effective
how is African trypanosomiasis transmitted?
which species in West Africa?
which species in East Africa?
Trypanosomes transmitted by several species of Tsetse flies
West Africa- T. brucei gambiense
East Africa- T. brucei rhodesiense
what is the clinical presentation of african trypanosomiasis?
Trypanosome Chancre
Enlargement of lymph nodes
Neurologic manifestations
what are the neurologic manifestations of african trypanosomiasis?
Irritability
Personality changes
Day time somnolence, restlessness, insomnia
what are the treatments for african trypanosomiasis?
Suramin
Pentamidine
Eflornithine: effective for both hemolymphangitic and CNS involvement
onchocerciasis = ____
riverblindness
what does onchocerciasis predominantly effect?
Filarial infestation that predominantly affects cutaneous and ocular tissue
what causes onchocerciasis? how is it transmitted?
Cause by Onchocerca volvulus
Transmitted by Simulium black fly
where is onchocerciasis most common
Exclusively in humans living in tropical African belt and south America
Subcutaneous nodules that are located over bony prominences
Intermittent intensely pruritic dermatitis describes which disease?
onchocerciasis
how does chornic onchocerciasis present?
Chronic Onchocerciasis: thickened , wrinkled skin with hyperpigmentation (lizard or elephant skin)
most severe affect of onchocerciasis?
blindness
how is onchocerciasis treated
ivermectin: 1 week microfilaries dissapear from skin; 3 months microfilarie dissapear from eye
nodulectoy
older drugs: suramin and DEC associated with severe hypersensitivity and dangerous toxic rxns
mazzotti reaction
what is tungiasis?
where is tungiasis endemic?
what causes the disease?
what is tungiasis rarely associated with?
Infestation caused by the burrowing flea, Tunga penetrans
Endemic in Central and South America, the Caribbean Islands, Africa, Pakistan and India
Impregnated female flea burrows into skin causing 1 cm nodule and erythema
Rarely associated with gangrene, tetanus and auto amputations
how is tungiasis treated?
how are eary lesions treated?
how are late lesions treated?
what are some preventative measures?
May spontaneously resolve
**Early lesions: **Removal of gravid female with a needle
**Late lesions: **Surgical curettage, electrodessication, excision
**Topicals: **Chlorophenothane, 4% formaldehyde, chloroform, turpentine
Niridazole
Tetanus prophylaxis
**Preventative measures: **Wear shoes, void sitting directly on beaches
what causes cutaneous myiasis?
usually cutaneous mysiasis is minimal morbidity unless it involves ______and________
Cause: Infestation of skin by fly larvae
how: Larvae inhabit skin wound or burrow into the dermis causing boil-like lesions
Usually cause minimal morbidity unless they involve nasal cavity and sinuses
what type of lesions does dermatobia hominis cause?
where are these lesions on the poby?
what happens after 24 hours?
is sensation of movement observed?
Causes boil-like lesions
Usually on scalp, face ,forearms and legs
24 hours after penetration pruritic papules form 1-3 cm in diameter
Lesions may be painful, tender and may become crusted and purulent
Sensation of movement may be observed
how do you treat dermatobia hominis?
should you remove forcibly?
how can you occlude/suffocate the bug?
Myiasis is a self limiting infestation
Do not remove forcible
**Occlusion/suffocation: **Bacon, petroleum jelly ,beeswax , nail polish
Injection of lidocaine at base of lesion
Surgical removal
which activities increase risk of myiasis?
Do not wear wet clothes
Do not rest on sandy areas
Use insect repellents
Avoid trips to Belize
test question: how do cimicid bedbugs bite?
where do they hide during the day?
Bites often in linear groups of three: BREAKFAST, LUNCH and DINNER
Hide in cracks and crevices, behind peeling paint during day
bedbuds may be Maybe vectors for ______ and ______
Maybe vectors for hepatitis B\ Chagas disease
bedbug dung may play a role in _______
asthma
how do you treat bedbugs?
Elimination of cracks and crevices
Removal of roosting bats or birds
Use of insecticides (dichlorvos)
Use of insect repellents
Cannot starve them, survive 1 year without feeding
which bugs are know as kissing bugs?
which causative agent of Chagas disease do they spread?
what is unique about their life cycle?
how do trypanosomes spread?
AKA kissing bug due to predilection to bite on or near the lips
Spread T. cruzi the causative agent of Chagas disease
Kissing bug takes blood meal then turn around and defecate immediately after feeding
Trypanosomes spread by victim scratching
what is head lice called?
what is body lice called?
what is pubic lice called?
Pediculosis capitis: Head Lice
Pediculus humanus var. capitis
Pediculosis corporis: Body Lice
Pediculus humanus var. corporis
Phthiriasis Pubis: Pubic Lice
Phthirus pubis
how many eggs can a female louse lay?
how long do lice live?
how do they survive?
how long can they live off a human host?
Range from 1.5 -4.5 mm in length
Female may lay up to 300 eggs (nits)
Live for approximately 30 days
Pierce skin every few hours to receive blood meal
Can live off human host for 2 days
how are head lice transmitted?
how are they treated?
what is used in resistant cases?
which is more common: reinfection or resistance?
Transmitted by direct contact or through fomites ( combs, brushes, hats bedding)
Treat with 1% permethrin cream rinse
Leave on 10 min. Thoroughly rinse.
0.5% malathion lotion in resistant cases
Fine tooth comb to remove nits
Re-infection more common than resistance
body lice
how common are they?
where do they hide?
what may be the only symptom?
what is the clinical presentation?
what are maculae ceruleae?
Less common in general population
Lice hide in seams of clothing and nits attach to clothing
Pruritus may be only symptom
Red papules under arms ,upper shoulders, neck
Maculae ceruleae- bluish/brown hemosiderin laden macules ( intradermal hemorrhage at lice feeding sites)
what are body lice vectors for? (3)
how to you treat body lice (3)?
Vector for: Epidemic typhus (Rickettsia prowazekii) Trench fever (Bartonella quintana) Relapsing fever (Borrelia recurrentis)
Treatment
Eradicate lice from clothing
Laundering in hot water
Drying at high temperature
pubic lice aka crab lice
how are they transmitted?
are they limited to the pubic area?
can they also cause maculae ceruleae?
- *_ transmitted by sexual contac_**t but can be obtained through contact with clothing or infested hairs
- *Not limited to pubic area**
- *May effect eyebrows, eyelashes, hair and scalp**
- *Can also cause maculae ceruleae**
how are pubic lice treated?
Same as head lice
Permetherin 1 % lotion for 10 min.
Eyelids- use occlusive ophthalmic ointment applied to eyelid margins for 10 days
Treat sexual partners too!
which disease = seven year itch?
Scabies
what is scabies caused by?
what about the distribution?
scabies lives its entire life where?
is it a known vector for disease?
how long has it been a companion of humans?
Caused by female mite sarcoptes scabiei var. hominis
World wide distribution
Lives entire life within epidermis
Not a known vector for disease
Common companion of humans over 2500 years
when is the pruritis of scabies worse?
what is its primary lesion?
where is it commonly found in body?
where is it involved in the infant?
Severe pruritus, often worse at night
Burrow is the primary lesion
Most commonly found in interdigital web (very common place) space wrist flexor surfaces of the elbows, areola and penis, scrotum, umbilicus belt line
Secondary papules, pustules vesicles more prominent than burrows
Involvement of head and face in infant
how is scabies diagnosed?
skin scraping demonstrating:
mites
scybala
eggs
how is scabies treated?
do you need to treat the entire family?
can patients itch one month after tx?
Permethrin 5 % overnight to all skin surfaces.
Wash cream off in morning
Treat all family members
Repeat in 1 week
Wash all clothing and bedding after treatment in hot water
Patients may itch for 1 month after treatment
what are some other tx of scabies?
5-10 % precipitated sulfur in petrolateum (overnight for 3 nights)
lindane overnight out of favor due to potential toxicity
crotamitin
ivermectin repeat in 1 week
what are the main spiders of concern in the US?
brown recluse
hobo spider
black widow
describe the brown recluse spider’s appearance?
wehre is it most abundant?
is it aggressive?
Fiddle back or violin spider due to dark brown markings on head and thorax
Most abundant in warmer climates they have been identified from Florida to Maine
Non aggressive spider
Will not bite unless disturbed
what is the range of severity for the bite of the brown recluse spider?
how does the bite appear?
wihch 4 systemic reactions can occur due to bite of brown recluse?
Vary from mild local reaction to ulcerative necrosis with eschar
Only ~25% get necrotic reaction
Bite often appears with central mottling and blister with surrounding blanched halo and erythema
Systemic reactions include shock, hemolysis, renal insufficiency and DIC
what is the major toxin of the brown recluse spider?
what does it interact with?
how does hylauronidase allows for eschars to do what?
Sphingomyelinase D major toxin produced by brown recluse spider
Interacts with serum amyloid protein
Hyaluronidase allows eschars to spread in gravity dependent fashion
how do you tx brown recluse spider bite?
Rest, ice(decreases immune response, may inactivate toxin), elevation
Interdermal injection of polyclonal anti-Loxoxceles Fab fragments
Hyperbaric oxygen
Dapsone: Check G6PD first
Prednisone
what type of web does it build?
is the hobo spider aggressive?
where is it found?
One of many aggressive spiders that build funnel shaped webs
Large, hairy, aggressive
Found in dark, moist areas, especially basements
T. agrestis is 4-5 cm in diameter, mostly found in the pacific northwest
are hobo spider bites painful?
can bites lead to ensuing necrosis and _____-?
what are the systmeic symptoms?
note: hemolysis and thrombocytopenia have been reported
Bites are typically not painful
Ensuing necrosis can lead to amputation
Systemic symptoms include headache, nausea and weakness
Hemolysis and thrombocytopenia reported
what is the tx for hobo spider?
largely supportive
no specific antivenin
what is clinical presentation of black widow bite in 1st 30 minutes?
what does venome cause depletion of ?
what type of pain does black widow bite produce?
can you die from black widow bite?
Local erythema, sweating piloerection at wound site with in first half hour
Venom causes depletion of acetylcholine at motor nerve endings and release of catecholamines at andrenergic endings
May produce abdominal pain(very severe),muscle spasm mimic an acute abdomen
Headache, paresthesias, nausea, vomiting, hypertension paralyisis
Death is uncommon
how do you treat black widow spider bite? (3)
Intravenous calcium gluconate
Analgesics
L mactans antivenin for severe cases
