L12: Cestodes

Question 1

Medically/ Economic importance of Echicococcuss species

Answer 1

E. granulosus and E. multilocularis

Question 2

Echinococcus Disease caused, discuss hosts

Answer 2

echinococcosis/ hydatidosis/ hydatid disease

Definitive host: carnivores
Intermiediate: herbivores

Humans: accidental intermediate hosts from zoonosis

smallest Taeniidae tape wrms

Question 3

Describe physiology of Echniococcus species

Answer 3

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

Question 4

Specifically compare E.granulosus and E mulitocularis, larval/cysts…

Answer 4

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

Question 5

Which Echinococcus is most dangerous most common

Answer 5

E. granulosus: most common, least pathogenic
E. multilocularis: most dangerous

Question 6

Describe the life cycle of Echninococcus species

Answer 6

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

Question 7

Why are humans accidental hosts of Echinco species, human part of life cycle

Answer 7

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

Question 8

Wahat does E. granulosus cause, main reactions, worse form

Answer 8

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

Question 9

What does E.mutli cause

Answer 9

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

Question 10

Epidemiology of E. granulosus

Answer 10

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

Question 11

Epidemiology of Echinoco multi

Answer 11

northern hemisphere, canada

Question 12

Diagnosis of echnio

Answer 12

symptoms, history of area, contact with dogs

imaging to see cysts

test serum for antibiotics, cystic fluid antigens

Question 13

Treatment of Echinococcosis

Answer 13

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

Question 14

What are signs of Echino in animals

Answer 14

wild canids dont show signs of disease

dogs/cats may have loss of appetite, nausea, vomiting, pain, jaundice

Question 15

What is Hymenolepis, medically important, general characteristics

Answer 15

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

Question 16

Compare general characteristics of H. nana and H. diminuta

Answer 16

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

Question 17

Life cycle of H species and special thing with H. nana

Answer 17

Eggs and cystercoids are infective
Adult
Oncospheres

H nana can cause internal infection when hexacanth embryo is released and penetrates villi

Question 18

How does internal autoinfection happen in H. nana

Answer 18

Internal autoinfection may occur, in which case, eggs release their hexacanth embryo, which penetrates the villus. Internal autoinfection allows infection to persist for years

Question 19

Describe clinical presentation, Diagnosis and Treatment of Hymenolepis

Answer 19

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

Question 20

What is Dipylidium canium

Answer 20

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

Question 21

Diagnosis and Treatment of D. caninum

Answer 21

diagnosis by seeing gravid proglottid or eggs in poop

praziquantel

Question 22

What is Diphyllobothrium latu

Answer 22

broad fish tapeworm

parasites many large mammals (bears, cats, seal)

Western Canada but worldwide

the long and broad proglottid

the longest tapeworm in humans

Question 23

Explain D. latum general physiological characteristics, what makes it special

Answer 23

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

Question 24

Outline Life cycle of D. latum

Answer 24

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

Question 25

Symtpoms, Diagnosis, Treatment and prevention of D. latum

Answer 25

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

Question 26

what are psychosomatic manifestions

Answer 26

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