Parasitic diseases Dan Flashcards
T/F
The main parasites are Helminths (worms) and Protozoa
True
What are the main Helminth groups?
Nematodes (round worms, pinworms and hook worms)
Cestodes (flatworms/tapeworms)
Trematodes (flukes)
What are the main Protazoal diseases?
Leishmaniasis (most important for derm)
Amoebiasis
Trypanosomiasis
Toxoplasmosis
What are the main Nematode diseases?
larva migrans, onchcerciasis, gnathostomiasis, filiariasis, Loiasis, Drancunculiasis, Strongyloidiasis
Enterobiasis (Pinworm/threadworm)
Ancylostomiasis (Hook worm)
What are the main Cestode diseases?
Cysticercosis and echinococcosis
Sparganosis
What are the main Trematode diseases?
Schistosomiasis
Paragonimiasis
Fascioliasis
Cercarial dermatitis(swimmer’s itch)
what organism is responsible for cutaneous larva migrans?
Ancylostoma spp; (BCC)
braziliense, caninum or ceylanicum
hookworms which can infect domestic dogs or cats as well as foxes, wolves, wild dogs and cats etc. The larvae is what infects humans
where is cutaneous larva migrans acquired and how?
In North, C and S America and parts of asia
pts walks barefoot/lies in outdoors; sandy area etc
hook worm eggs have been passed in feaces from infected animal and hatch into filariform larvae in sandy soil so are present on the ground and penetrate skin
T/F
The incubation time for cutaneous larva migrans is approx 2 weeks
False
1-6 days
T/F
some pts with cutaneous larva migrans get systemic symptoms including cough and wheeze
True
small percentage
rarely can get Loefller’s syndrome - eosinophilic pneumonia due to parasite infection
T/F
Creeping eruption and ground itch are other names for cutaneous larva migrans
True
also sandworms and Plumbers itch
what are the clinical features of cutaneous larva migrans?
starts as dermatitis at site of entry of larva - often feet or buttocks from standing or sitting on affected ground
can stay like that for wks-months before typical meandering serpiginous trail of erythema begins or can begin very quickly
dermatitis can be raised and vesicular
trail moves slowly 1mm-3cm per day
is 3mm wide and up to 15-20cm long
can be single or many
self limiting - usually resolves in 4-8 weeks when nematode dies
can be secondary impetiginisation - 10%
can get hookworm folliculitis with up to 200 follicular papules and pustules confined to one part of the body
Can get EM
How is cutaneous larva migrans diagnosed?
A typical eruption in a pt with a consistent Hx is adequate for a clinical diagnosis
If tests required can take biopsy of folliculitis showing nematode larvae but often larvae have migrated by the time the biopsy is taken
or skin scrapings from serpiginous trail showing larvae and dead nematodes
T/F
Humans are a dead end host for the dog or cat hookworm
True
cannot penetrate basement membrane of skin as lack specific collagenases
nematode dies in 4-8 weeks
How is cutaneous larva migrans treated?
No Rx - self limiting
can treat to alleviate symptoms
single dose ivermectin - preferred Rx for adults and children over 15kg
3 day course of albendazole - 400mg for adults and children over 10kg or 200mg for children under 10kg
both taken with fatty food
Can use topical thiabendazole 10%; Grind up two 500mg tablets into 10g of WSP and apply bd for 1 week
How does cutaneous larva migrans differ clinically from larva currens?
Migrans; well defined narrow, often raised train Moves slowly max 3cm/day often few mm only Currens; Poorly defined urticated trail Moves quickly, 5-15cm per hour
T/F
Oncherciasis is caused by Onchocerca volvulus, a filarial nematode
True
T/F
Oncherciasis is also called sleeping sickness
False
Oncherciasis is also called River blindness
Which organs/systems are most affected by Oncherciasis?
Skin
Eyes
Lymphatics
T/F
Oncherciasis is transmitted by the female sandfly
False
Oncherciasis is transmitted by the female black fly (Simulium damnosum)
T/F
onchocercomas are the first and most characteristic skin finding of Oncherciasis
True
subcutaneous nodules over bony prominences esp skull which are fibrous tissue surrounding coiled adult worms
What are the skin manifestations of Oncherciasis?
Onchocercomas
Acute papular onchodermatitis on trunk and limbs
Chronic papular onchodermatitis on buttocks, hips, shoulders
Lichenified onchodermatitis - usually one thickened and lichenified area on a limb
Atrophy around waist, butocks and thighs and Hanging groin
Depigmentation known as leopard skin
T/F
Microfiliarae in Oncherciasis cause conjunctivitis, sclerosing keratitis, uveitis, optic atrophy, and glaucoma which can lead to blindness
True
T/F
Oncherciasis is the most common infective cause of blindness
False
second most common infective cause of blindness