L12: Cestodes Flashcards
Medically/ Economic importance of Echicococcuss species
E. granulosus and E. multilocularis
Echinococcus Disease caused, discuss hosts
echinococcosis/ hydatidosis/ hydatid disease
Definitive host: carnivores
Intermiediate: herbivores
Humans: accidental intermediate hosts from zoonosis
smallest Taeniidae tape wrms
Describe physiology of Echniococcus species
have 3 proglottids, one imature, 1 mature 1 gravid proglottid
*scolex has rosetllum with double row of 26 hooks, 4 suckers and small neck
*life span of 5-12 months, infection can have hundreds of worms
Specifically compare E.granulosus and E mulitocularis, larval/cysts…
E. granulosus
“dog tapeworm”
def host: dogs/canids
intermediate: sheep, herbiovres
accidental: humans (very common, least pathogenic) small animals
larval stage causes cycstic echniococcus
cysts = “unilocular”
E. multilocularis
“fox tapeworm”
def host: foxes
intermediate: rodents
accidental: humans, wild animals
larval stage: alveolar echinococcosis
cysts: multilocular
Which Echinococcus is most dangerous most common
E. granulosus: most common, least pathogenic
E. multilocularis: most dangerous
Describe the life cycle of Echninococcus species
Gravid proglottid and egg infectious
6 hook oncospheres
Gran .. lung and liver … thin walled hyatid cyst have protoscolices
Mult… liver …think walled multiocular hyatid cysts have protoscolices
If rapture it’s secondaey
Why are humans accidental hosts of Echinco species, human part of life cycle
Become infected by ingesting effs, usually from contact with dogs, raw plants
Oncospheres released in intestine
cyst develop in liver for E. multi but everywhere for E. granu => if raptured they will spread
Wahat does E. granulosus cause, main reactions, worse form
Cystic Echinococcus
cause inflammatory reaction => cyst but reaction can remain silent for 20 yrs
*first symptoms from pressure of cycsts => cause atrophy => jaundice, kidney dysfunction, seizures
*also cysts rapture and release hydatid fluid => allergic reaction => anaphylactic shock
can spread => secondary echinococcus which is more serious
What does E.mutli cause
Alveolar Echinococcosis
alveolar cyst in groups of interconnected small cysts, not encapsulated like hydatid cyst => no fluid
affects the liver, slow-growing, destructive tumours => calcify => secondary echinococcus => can be fatal
Epidemiology of E. granulosus
worldwide
predator-prey relation causes sylvatic echino
zoonotic human disease => mostly dog places, rural, use dogs to herd livestock, dogs to clean up shit
some strains have adapted to have different epidemiologists
Epidemiology of Echinoco multi
northern hemisphere, canada
Diagnosis of echnio
symptoms, history of area, contact with dogs
imaging to see cysts
test serum for antibiotics, cystic fluid antigens
Treatment of Echinococcosis
success of treatment depends on echino type, sometimes surgical: liver resection, but may cause allergic reaction from the fluids
for cystic: puncture aspiration
chemotherapy
albendazole
What are signs of Echino in animals
wild canids dont show signs of disease
dogs/cats may have loss of appetite, nausea, vomiting, pain, jaundice
What is Hymenolepis, medically important, general characteristics
small tapeworm
H.nana: common, worldwide
H. diminuta: less frequent
4 suckers with retractable rostellum, proglottids are longer than they long
have 3 defined testes and single bilobed ovary
Compare general characteristics of H. nana and H. diminuta
H.nana
“drawf tapeworm”
def host: rodents/humans
rostellum single circle with with 20-30 small hooks
very small
4-6 weeks
H.diminuta
“rat tapeworm”
def host: rodents and humans
intermediate: grain eating insects
Rostellum with no hooks
lives as long as rodent
Life cycle of H species and special thing with H. nana
Eggs and cystercoids are infective
Adult
Oncospheres
H nana can cause internal infection when hexacanth embryo is released and penetrates villi
How does internal autoinfection happen in H. nana
Internal autoinfection may occur, in which case, eggs release their hexacanth embryo, which penetrates the villus. Internal autoinfection allows infection to persist for years
Describe clinical presentation, Diagnosis and Treatment of Hymenolepis
symtomless and self limiting so humans can have many => may lead to autoinfection => mucasal intestinal wall damage
children are most at risk, loss of pepeite, poop, abdominal pain, toxins cause allergies
Diagnosis: eggs in poop
Treatment: anthelminitic drugs like praziquantel/ Niclosmaide
What is Dipylidium canium
cucumber or flea tapeworm or
- pet and fox parasite, worlwide
- rarely infects umans
Scolex is conical with retractable rostellum and 1-8 hooks
Proglottid has two sets of reprodcutive organs with a genital atrium on each
lateral edge hence the name ‘double-pored’ tapeworm
Eggs
* in capsules/packets each with 8-25 eggs, humans have many
Egg packets
Progglotid
* motile when freshly passed, maggoty
Diagnosis and Treatment of D. caninum
diagnosis by seeing gravid proglottid or eggs in poop
praziquantel
What is Diphyllobothrium latu
broad fish tapeworm
parasites many large mammals (bears, cats, seal)
Western Canada but worldwide
the long and broad proglottid
the longest tapeworm in humans
Explain D. latum general physiological characteristics, what makes it special
Have 2 brothria which are slit like adhesive regions that pink the intestinal wall
In the mature proglottid testes are scattered throughout & the male and
female genital openings are separate and located mid-ventrally
Gravid proglottids remain attached and shed eggs into the gut through a uterine pore and passed in the feces
1,000,000 unembryonated eggs per day
Outline Life cycle of D. latum
Eggs are passed unembryonated in feces
2. Under appropriate conditions, the eggs mature i.e., embryonate in
water (~18-20 days)
3. Embryonated eggs yield oncospheres which develop into coracidia
4. After ingestion by a suitable crustacean (1st intermediate host),
coracidia develop into procercoid larvae
5. Procercoid larvae are released from the crustacean upon predation
by the 2nd intermediate host, usually a small fish, and migrate into
the deeper tissues where they develop into a plerocercoid larvae.
This is the infectious stage for the definitive host. Because humans
do not generally eat these small fish species raw, the 2nd
intermediate host probably does not represent an important source
of human infection.
6. The small 2nd intermediate hosts can be eaten by larger predator
species that then serve as paratenic hosts. The plerocercoid larvae
migrates to the musculature of the larger predator fish
7. Humans (and other definitive host species) acquire the parasite via
consumption of undercooked paratenic host fish
8. In the definitive host, plerocercoid develops into adult tapeworms in
the small intestine. Adult diphyllobothriids attach to the intestinal
mucosa by means of the two bothria on their scolex
Symtpoms, Diagnosis, Treatment and prevention of D. latum
symptoms: abdominal pain, weight loss, nervous disorders, arise from reaction to metabolic waste => psychosomatic manifestions
has affinity for vitamin B12 in jejunum, so it competes with host causes anemia
Diagnosis: see eggs in poop or vomit
Prevention: brine saturation or freeze fish, education
Treatment: anthelmintics praziquantal
what are psychosomatic manifestions
Symptoms are often attributable to the patient’s reaction to the parasite’s metabolic waste, degenerating
proglottids, irritation of the intestinal mucosa or psychosomatic manifestations after patient learns of the
presence of the worm