Stings, Bites, and Bugs Flashcards
causes american trypanosomiasias
T. cruzi (chagas disease)
causes african trypanosmiasis
T. brucei
where is american trypanosomiasias endemic?
central and south america
How is T. cruzi transmitted?
infected reduviid bugs and occasionally infected blood
Romnana sign
T. cruzi edema of the palpebral and periocular tissue due to entry through the conjunctiva
describe the pathogenesis of american trypanosomiasias
reduviid bug bites you –> poops in the bite and deposits T. cruzi in skin –> T. cruzi infects cells and multiplies –> spreads locally or systemically if it gets into blood stream
characteristic finding of Chagas dz
swollen eye
Acute phase of chagas disease
local erythma and swelling of regional lymph nodes
chronic phase of chagas dz
**can occur years to decades later** Cardiac and GI manifestations (heart failure, arrhythmias, megacolon)
How is african trypanosomiassis transmitted?
tsetse fly
Describe the clinical presentation of african trypanosomiasis
chancre at bite site LN enlargement day time somnolence or insomnia irritability or personality changes
predominatly effects cutaneous and ocular tissue
onchocerciasis ( aka river blindness)
How is onchocerciasis transmitted?
Simulum black fly (carry the bug onchocerca volvulus)
Clinical presentation of acute onchocerciasis
intense puritic dermatitis with subcutaneous nodules over bony prominences
Clinical presentation of chronic onchocerciasis
-thickened, wrinkled skin with hyperpigmentation (lizard or elephant skin) -conjunctivitis –> blindness in severe cases
Mazzotti reaction:
assc with onchocerciasis treatemtn, severe chills, lymphadenopathy due to break down of organism and the large immune response that results
Impregnated flea burrows into skin and causes a 1 cm nodule and erythema
Tungiasis *flea is called Tunga penetrans
fly larvae inhabit skin sound or burrow into dermis and cause boil-like lesions, eventually a fly will emerge from the boil
Cutaneous Myiasis **fly is called Dermatobia hominis (aka Human Botfly
describe the lesions assc with cutaneous myiasis
1-3 cm painful, tender lesions in which movement it felt
How to avoid cutaneous myiasis
avoid belize! wear bug repellant, dry clothes, and do not sit in sandy areas
Bites are often seen in a liner group of 3
bed bugs **breakfast, lunch, and dinner
causitive agent of chagas disease
reduviid bug (aka kissing bug) carrying t. cruzi
Assc with maculae cerulease
lice (body and pubic) = blue/brown hemosiderin laiden macrophages due to intradermal hemorrages at lice feeding site
What disease are body lice a vector for?
typhus (rickettsia prowazekii) trench fever (bartonella quintana) relapsing fever (borrelia recurrentis)
Where on the body is scabies most commonly found?
interdigital web wrist flexer surfaces of the elbow
pathogenesis of scabies
mite burrows in epidermis and lays eggs –> eggs hatch –> continues over and over ==> causes purities
How is scabies diagnosed
mites scybala (feces) eggs
Describe the bite mark from a brown recluse
central mottling central blister–>eschar –> ulcerates blanched halo erythema surrounding
What are the systemic reactions assc with brown recluse bite?
shock hemolysis renal insufficiency DIC
What is the major toxin produced by brown recluse?
sphingomyelinase D hyaluronidase allows eschars to spread (in gravity dept reaction)
bites are typically not painful and central necrosis can lead to amputation
hobo spider
assc with hemolysis and thrombocytopenia
hobo spider bite
most common complaint with black widow spider bite
abdominal pain
What biochemical effect does the black widow spider have?
depletion of Ach and increased release if catecholamines **not depletion of Ach esterase… sorry….***
Tx for black widow spider bite
IV calcium gluconate
chancre at bite site LN enlargement day time somnolence or insomnia irritability or personality changes
african trypanosomiasis
-thickened, wrinkled skin with hyperpigmentation (lizard or elephant skin) -conjunctivitis –> blindness in severe cases
chronic onchocerciasis
intense puritic dermatitis with subcutaneous nodules over bony prominences
acute onchocerciasis
1-3 cm painful, tender lesions in which movement it felt
cutaneous myiasis
central mottling central blister–>eschar –> ulcerates blanched halo erythema surrounding
brown recluse bite
brown recluse bite
“classic red, white, and blue sign”
What is this?
scabies
bed bugs
cutaneous myiasis
