Bugs/stings/bites Flashcards
Location/transmission/presentation of American trypanosomiasis chagas disease
central and south america, Texas, florida;
transmission: T. cruzi infected reduviid bugs and infected blood
Present: systemic=> ANS, heart, GI
What sign is associated with American trypanosomiasis chagas disease? describe it
Romana sign=> edema of palpebral and periocular tissue from entry through conjunctiva
What is the life cycle of T. cruzi?
T. cruzi in feces of reduviid bug; bite then defecates into bite; T. cruzi enters wound; invades cells and amastigotes (multiplies); amastigotes change into trypomastigotes and enter blood; bug bites infected human again
When is Trypanosoma cruzi cause clinical disease?
once the trypomastigotes invade cells and change into amastigotes and multiply
What is the acute phase of chagas disease clincially?
localized erythema, LAD; anorexia; facial edema; lower extremity edema
Romana sign
How does chronic chagas disease present clinically?
occurs years to decades later with heart and GI manifestations
How is chagas disease treated?
Nifurtimox; Benzimidazole
What is the life cycle of Trypanosoma brucei?
bite then multiply in the midgut leading to metacyclic form->binary fission to trypomastigote then back to infecting the Tsetse fly again
How does the african trypanosomiasis present clinically?
Trypanosome chancre; node enlargement; neurologic manifestations (irritable, personality changes, day time restlessness)
What is the Tx for african trypanosomiasis
Suramin; Pentamidine; Eflornithine (CNS, hemolymphangitic)
What causes onchocerciasis (river blindness)?
onchocerca volvulus that is transmitted by the simulium black fly causing cutaneous and ocular tissue infestation (blind if chronic)
Who is at risk for Onchocerciasis?
humans living in tropical African belt and S. america
How does onchocerciasis present clinically?
Subcutaneous nodules over bony prominences; intermittent intensely pruritic dermatitis; microfilariae in conjunctivae cause sclerosing keratits, uveitis, optic atrophy, glaucoma
Onchocerciasis Tx
Nodulectomy; Ivermectin;
What is very important to avoid when doing a nodulectomy for onchocerciasis?
Mazzotti rxn causing fever, chills from immune response due to a breakup of the organism
Location/transmission/presentation of Tungiasis
endemic in Central and South america, caribbean, Africa, pakistan and india;
impregnated female flea burrows causing nodule and erythema;
Tungiasis Tx
may spontaneously resolve; early lesions (removal w/ needle); late lesions (excision); apply topicals;
PREVENT: WEAR SHOES
What is cutaneous myiasis?
infestation of skin by fly larvae that inhabit skin (scalp, face, forearms, legs)wound or burrow into dermis like a boil => sensation of movement
What is the Tx for myiasis?
self limiting that can be suffocated out via bacon
How can a person take precaution to prevent human botfly infections?
avoid activities that increase risk of myiasis (no wet cloths, no resting on sandy areas, use insect repellent; AVOID BELIZE)
Cimicids (bedbugs) have what distinguishing characteristic?
feed at night (mattress) by biting in linear groups of 3 (breakfast, lunch, dinner)
Name the name and location for the different types of lice
Pediculosis capitis (head lice at schools) Pediculosis corporis (body lice from war/poor) Phthiriasis pubis: (pubic lice from sex)
What is the life cycle of a louse?
female 300 eggs; lives for 30 days; human host blood dinner
How is head lice transmitted and treated?
transmitted by direct contact or fomites
Tx with 1% permethrin cream rinse and comb to remove nits
What are the Sx of body lice and view histologically?
Pruritis and give a maculae ceruleae of bluish/brown hemosiderin laden macules
Pubic lice from sexual contact is found where and causes what?
not limited to pubic areas but can be present in eyebrows, eyelashes, hair and scalp => cause maceulae ceruleae
Location/transmission/presentation of scabies
world wide;
femal mite scabiei that lives w/in epidermis;
severe pruritus in INTERDIGITAL WEB SPACE, wrist flexors, elbows, penis
How is scabies diagnosed?
skin scraping demonstrating mites, scybala, eggs
What are characteristics of a brown recluse spider?
fiddle back; warmer climates; non agressive; not bite unless disturbed
If a brown recluse does bite, how will it present clinically?
central mottling and blister with blanched halo and erythema;
Why is it not good to surgically remove scab from spider bite?
toxin will become systemic =>shock, hemolysis, renal insufficiency and DIC
What is the pathogenesis of a brown recluse spider bite?
Sphingomyelinase D major toxin; interacts with serum amyloid protein; Hyaluronidase allows eschars to spread in gravity dependent fashion
What is the best Tx for a brown recluse bite?
R.I.C.E. with prednisone
What is the characteristics of a Hobo spider?
large(4-5cm), hairy aggressive found in dark, moist areas
What is the clinical presentation of a Hobo spider bite? Tx?
not painful; ensuing necrosis may lead to amputation
Supportive Tx
What are the characteristics of the black widow spider?
North america, large, shiny spiders with hourglass on abdomen
What are the clinical Sx of a black widow spider bite?
local erythema, sweating piloerection; venom causes depletion of Ach at release of catecholamines => leads to abdominal pain and muscle spasm
Tx for black widow spider bite?
IV calcium gluconate, analgesics
Lice associated diseases
typhus, relapsing fever, trench fever
Fleas associated diseases
bubonic plague; typhus; tungiasis;
budbugs associated diseases
possibly HBV
flies, mosquitos associated diseases
cutaneous myiasis, malaria, yellow fever, dengue fever, viral encelphalitis onchocerciasis, sleeping sickness, West nile fever
Reduviid bugs associated diseases
chagas disease
spiders associated diseases
necrotic arachnidisim, paralysis
Ticks associated diseases
granuloma formation; lyme borreliosis, RMSF, Q fever; tularemia
Mites associated diseases
hypersensitivity dermatitis; scrub typhus; scabies; rosacea
