Worms Flashcards
Helminths
worms
How do worms cause damage?
slow: the worm or its eggs attempt to escape
rapid: tissue damage as humans are not the natural host
Types of helminths
Cestodes (tape worms)
Trematodes (flukes)
nematodes (round worms)
Cestodes (tape worms)
flat and long, segmented
head, neck, segments (oldest segments die and fall off)
Trematodes
flat and
Nematodes
=round worms
hookworms
ascarids
strongyloides
Pork and Beef tapeworm - hosts
definitive host: human
intermediate host: cattle, pigs
Life cycle of pork and beef tapeworm
cyctocicosis
human develops cysts
by being the accidental intermediate host
cystocircosis
hydatid
dog tape worm
dogs and foxes are definitive hosts
humans are accidental intermediate hosts
sheep and goats are true intermediate hosts
treatment and prevention - cestodes
praziquantel for human tape worms and for dogs
treatment for cysts - cestodes
Hydatid: surgery, PAIR, long term albendazole, praziquantel
Treatment of cysticercosis - cestodes
albendazole, praziquantel and steroids
prevention of worms - cestodes
hygiene
de
Dx of cestodes
serology and imaging
Schistosomiasis
Helminth disease
How many species of schistosomiasis?
4 (africa, SE asia, south/Central America)
Damage by sschistosomiassis
XXX
Life cycle of schistosomiasis
- worms in venus plexuses, produce eggs, eggs migrate through bladder or stool
- released into water
- in snail
- go in through human foot in fresh water
Definitive and intermediate hosts of schistosomiasis
def: humans
intermediate: snails
Diagnosis in Schisto
microscopy
- urine: s haematobium
- stool: s mansion, s japonica
serology
biopsy
response to treatment (not in the UK)
Treatment of schistosomiasis
praziquantel
prevention of schisto
HARD
kill snails
destroy snail habitat
mass treatment
interrupt transmission (no swimming, no washing etc)
where do adult schisto worms live?
blood vessels
schisto - how is disease caused
egg deposition
complications of schistosomiasis
Soil transmitted helminths
ascaris lumbricoides
trichuris trichuria
hookworm
strongyloides stercoralis
ascaris lumbricoides
trichuris trichuria
hookworm
strongyloides stercoralis
ascaris lumbricoides
trichuris trichuria
hookworm
strongyloides stercoralis
hookworm
strongyloides stercoralis
with ascaris and with hookworm there is a stage where they migrate through the body
How do soil transmitted helminths cause disease?
Life cycle of ascaris
- eggs swallowed with food
- find their way into duodenum and mature to adults
strongyloides
only helminth capable of auto infection
xxx
life cycle of strongyloides
life cycle of strongyloides
they can mature into larvae before leaving the rectum ?
Filariasis
variety of nematode infections spread by black flies and mosquitoes
types of filariasis
lymphatic (Wucherer, Brugia)
subcutaneous (Onchocerciasis, Mansonella, Loa loa)
serous cavity (Mansonella, dirofilaria, don’t really cause many medical problems)
River blindess - pathogen
diagnosis of filariasis
- find microfilariae (blood film, skin snips)
- antibodies (ELISA, IFAT)
- XXX
life cycle of filariasis
- larvae enter skin via mosquito
2.
Myiasis
parasitisation of human flesh by fly larvae
motile maggots under skin
main flies in myaisis
Bot (S. America) - sometimes need surgery
Tumbu (Africa)
Eosinophilia causes
atopy
drug allergies ]makignancy (Hodgkins lymphoma, `NHL)
SLE and other systemic AID
some forms of vasculiti s
cholesterol embolisms
DON’T FORGET PARASITES
soil-transmitted helminths (strongylyloides)
schistosomiasis
filaria
leaking hydatid cysts
Does ascaris have a skin stage?
no
