Helminth infections Flashcards
what are the 3 worm groupings of helmiths
Nermatodes (round worms)
trematodes (flukes)
Cestodes (tapeworm
Describe nematode
aka roundworm
ascaris, hookworm, whipworm
have a round cross section common morpholoy
distint head whihc cotnaisn mouht
tial
name some trematodes (AKA fukes)
flattedn boyd shape can grow to 1-6mm lack a digestive tract
absorb nutrients across there rufrcae
FLukes
liver flukes, blood flukes (schistosomes)
Describe cestodes?
tapewomr (hyatids)
cestodes can grwo to extreem lenghts- up to 20m
Describe soil transmission of Helminths (nematodes)
ascariris, whipwroms, hookworms
strongyloide stercoralis (threawork or pin worm)- uk association
transmision of soil transmitted occurs via faecl orla-route
6 Fs of worm infections- Faewces, fluids, flies, fileds, finger, food
lack of adeuqat sanitation
Describe ascaris infections
ascaris lumbricoid (ascaris)- causativ agent of ascariasisi
largest of the roundworms (nematodes)
up to 35 cm on average
1 billion peoepl every year are infected
maybe responiobel fro 500K deaths a yearr- mainyl in children under 5
- ingesting food/water contaminated with eggs
- pass into intestine
- hatch and release larvae into the gut lumen
- larave penetrate fut wall and enter ciruclatory system and migrate to lung for further developed
- dveelop cough and then swallow larvae- furthr maturation in the gut
- mature worm mate and produc eegegs -expelled in faeces
how does the pathology of ascariasis manifesdt?
many asymptomatic
as worm burdne incerease- increase in symptoms (lethargy,weight loss, inability to concnetrate - competeiton for nutreitns with parasite
slow growht in kids
GI symptoms may even get bowel obstruction and intestinal bleeding
the developing larvae spreading to lungs may csaise respiraotry problems- Eosinophillic penumona (lofflers syndrome)
what is the treatment for ascariasis
Mebendazole
after stool sample analysi by light microsopcy looking for eggs
descrtibe the epidemiology of hook worms
widespread often concurent with ascariasis infections- same codntiomns 6Fs- faciliate dissemination of both
Prescen of ascaris is considered a riks factro for acwuiring hook worm)
ancylosotma doudenale, necator americanus
Describe the life cycle of hook worms
- similart to ascariais lung invovlemdnt- but egg doesnt have tp bne ingested
- eggs spread into environemnt via open defecation
- eggs hatch in soil and motile larva chemoattracted to the new host
- move towards skimn and then burrown
- larvae enter the skin - migrte to ciruclatory system to lung developmen
- coughed up swallowed an mature in intestine
what is this?
hookworm
as it enters the ksin causes an allergic reacgion a site of parasite pentrating and moving within skin- cutaneous larva migrans
what pathology do hookworms causes?
often asymptomatic
has small teeth like projects it sues to attache to the gut- damages the gut wall - cauases blood protieon and gfluid loss- malbasoption, hypoproteinaemai and anaemia
- manutrtion
- aneamria
- cardiasc complications due to blood loos and iron malbasoption
- severe acute pulmonary reactions (pneumonia) and gastrointestinal reactions
what is a hookworm that is spread by dogs- but cannot enter cirulation
Ancylostoma Caninum
not adpated to hmans but can enter the skin and cause cutaneous larva migrans
how do we treat hook worm>
detetc eggs in stool by light micoscopy
treatment- Mebendazole
what are trematodes (flukes)
tissue rsident helminths
parasitc worms that invade other areas of the body away from the pirmayr infeciton
Schistosoma—-? schiastomiasis (bilhazia)
What is schistosomaiiss (bilharazia)- most causive species and how do they manifest dofferently?
make up 85% of cases of bulharzia in africa
- S.haematobium- urogential/bladder problems
- S mansoni and S japonicum - cause intestinal and hepatic disease
Describe the life cycles of schistosomiasis? what intermediate host is needed
s. haematobium, s. mansoni and s japonicium have similar life cyccles
- require aquatic snail as intermediate host into humans
- infected human host shed. eggs into environemnt (fresh water)
- eggs hatch and parasite attached to snail
- in snails paraiste matures to infectious form and released into water
- chemoattracted to humans- penetrta skin and enter ciruclatory syste,
- migrate to live where they develop and mature into final worm stage
- S.haematobium- venous plexus of bladder—> urien
- Smansoni/S japonicicum- mesenteric veins of intestine- secret eggs into GI tract- faeces
what is this ?
swimmer sitch (inflamamtion and itching)- causeed by entry of the skin by the schistosomiasis
describe the presentation of S.haematobium
urogential schistosomiaiss
haematoutria- firbosis of bladder and ureter
increase risk of squmaous bladder cancr
women- gentila leison, vaginal bleeding, pain during intercourse
men- dmagae to the smeinal vesicle, prostate and othe organs- infertility
describe the presentation fo S.mansoni and S.japoncium
heptatic-intestinal schistomsosmais
abdominal pain, diarrhoea and blood in the stool
hepatomwgalty, splenomagaly
ascites/oprotal hyper ttension
schihistosomiasis treatment?
praziquantel taken for 2 days
Describe the life cycle of a cestodes (tapeworm)
1.
humans can act as intermeidate host (harbours sexually immature parasite) or defintiive parasite
- humans as definitve host
- pig or cow intermeidate host- ingest eggs and cust develop in infect anaimla musculature/tissues
- cyst cotnaining meat ingested by a huma- enters GI tract develops into adult form- shed in faces- ingested by another animal
- human as the intermeiadt host
- human ingets eggs - cysts then form inside the human tissues/musculatrure instead of animal- cysticerosis
what is cysticercosis? treatment
humans ingest eggs of tapeworm (cestodes) and then beocme the itnermeidat host- cyst formation in the body tissues- muscles (cysts can die and calcidied), eyebody, extraocular msucles etc
in severe cases get neurocysticerosis- seirzires headahces, dementia, meningtiis
need treatment- praziquantel or albendazole
what are hydatids? what are the 2 major forms of echinocccosis?
specialised form of tapeworm- also known as echinoccocccus
humans are the intermediate host
cystic echinococccosis (CE)
alveolar echinococcosis (AE)
