Cestodes Flashcards
Adult worms of the following cestodes are seen in the intestine of man, EXCEPT;
T. solium
E. granulosus
D. latum
Hymenolepis
None
E. granulosus
The parasitic tapeworm transmitted by inadequately cooked freshwater fish is:
D. latum
A 30-year old patient reported in the emergency room with complaints of fatigue, weakness, diarrhea, and numbness of extremities. The peripheral blood film revealed megaloblastic anemia and stool exam showed yellowish-brown operculated eggs. Which of the following parasites is likely to be the cause of the disease?
D. latum
Operculated eggs are produced by:
D. latum
Because of the similarities between the ova of T. solium and T. saginatam specific diagnosis can be made thru:
Demonstration of scolex
What is/are the drug of choice for T. solium infection?
Praziquantel
In the life cycle of D. latum, how many intermediate host is/are involved?
2
Common name of D. latum
Fish tapeworm
Bovine cysticercosis can be prevented thru the following measures, EXCEPT;
Thorough cooking of meat
Proper sanitary disposal of feces
Meat should undergo inspection
All
None
none
The larval form of T. solium can be seen in:
Pigs
The following tapeworms possess armed rostellum, EXCEPT;
D. caninum
T. solium
E. granulosus
T. saginata
None
T. saginata
In which of the following cestodes man can act as the intermediate host?
T. solium (man can be DH/IH)
Parasite-induced pernicious anemia is seen in infection with:
D. latum
Encysted larva of T. solium that can be present in measly pork:
Cysticercus
What is/are the intermediate host/s of Taenia saginata?
Cattle
Fertilized eggs that are broadly oval, golden brown in color, some can be mammilated, and classified as soil transmitted helminths. Identity is:
Ascaris lumbricoides
A roundworm acquired from the ingestion of meat containing the encysted larvae causing the encystment of the larvae in human striated skeletal muscle. Identity is:
Trichinella spiralis
Egg of this tapeworm is oval or sub-spherical with 4 to 8 polar filaments, resembles like a “fried egg”. Identity is:
Hymenolepis nana
The egg of this parasite was 1st discovered in the Philippines. Eggs are flat with bi-polar plug, peanut-shaped and presence of striated cell wall.
Capillaria philippinensis
Asymmetrical nematodal egg with one side flattened and the other convex with translucent shell. Identity is:
Enterobius vermicularis
A pseudophyllidean eggs that is usually yellowish brown in color with a moderately thick shell and an inconspicuous knob and an operculum.
D. latum
The eggs of an STH that are barrel-shaped, with protruding bipolar plugs and the ova are unsegmented.
Trichuris trichiura
The egg of this STH is ovoidal (egg-shaped), thin-shelled, colorless and passes 4-8 cell stage in the feces.
Hookworm
Tapeworm’s egg that has three pairs of hooklets and a striated outer shell resembling like kiwi slices. The eggs of the two species cannot be differentiated. Identity is:
Taenia
A dog tapeworm’s egg which is spherical in shape, thin-shelled with hexacanth embryo, and are passed out in packets containing 8-15 eggs. Identity is:
Dipylidium caninum
Which among the statement is/are false about cestodes:
A. Majority are long, unsegmented and resemble like tapeworms
B. Majority are long, segmented and resemble like tapeworms
C. Dorso-ventrally flattened
D. Adult worms are found in the intestinal canal of man and animals
E. None
A.
This region in an adult worm is provided with suckers & sometimes with hooks that serves as organs of attachment.
Head/scolex
This is the region of growth in an adult worm.
Neck
This is referred to as the body/trunk of the adult worm.
Strobila
The strobila consists of segment called _____________
proglottids
T or F. Cestodes are not separate (monoecious)
True
What are those that are absent and present in cestodes?
Absent: Alimentary canal
Present: Excretory & nervous systems; reproductive system
A type of segment of the strobila where male and female organs are not differentiated.
immature segment
A type of segment of the strobila where the male and female organs have become differentiated
mature segment
A type of segment of the strobila where the uteri are filled with eggs
gravid segment
A classification of cestodes that possess false or slit-like grooves called bothria
Pseudophyllidean cestodes
This is classified as the only pseudophyllidean cestode.
Diphyllobothrium latum (D. latum/fish tapeworm)
What is the larval stage for pseudophyllidean cestodes (D. latum)?
Plerocercoid in man
A classification of cestodes that possess cup-like round suckers called acetabula.
Cyclophyllidean
Common name for Taenia saginata
Beef tapeworm
Common name for Taenia solium
Pork tapeworm
Common name for Hymenolepis nana
dwarf tapeworm
Common name for Hymenolepis diminuta
Rat Tapeworm
Common name for Dipylidium caninum
Double Pored Dog Tapeworm
Larval stage in man of Echinococcus granulosus & Echinococcus multilocularis
Hydatid cyst
Larval stage in Man of Taenia solium
cysticercus cellulosa
Larval stage in man of multiceps multiceps
coenurus cerebralis
Larval stage in man of multiceps glomeratus
coenurus glomeratus
These are large worms consisting of a long chain of segments
Pseudophyllidean cestodes
Adult worm is yellowish grey in color. Dark central marking in the strobila are due to the egg-filled uterus. It measures 3 to 10 meters in length and its life span is for a period of 5 to 15 years.
D. latum
Scolex is spoon-shaped or spatulate and has no rostellum and no hooklets.
D. latum
Its neck is thin and unsegmented and is much longer than the head
D. latum
Its uterus at the center of the segment appears in the form of a rosette.
D. latum
It contains abundant granules and unsegmented ovum. It is inconspicuous operculum at one end and a small knob at the other end.
D. latum
T or F. Diphyllobothrium latum floats in saturated solutions of common salt.
False. It doesn’t float.
The first stage larva of D. latum
Coracidium; ciliated oncosphere
Second stage larva of D. latum
Procercoid (found inside cyclops)
The first intermediate host for D. latum
Cyclops
Third stage larva of D. latum
plerocercoid (sparganum)
The second intermediate host of D. latum.
Fresh water fish - perch, trout, salmon, pike
Final host of D. latum
man, dog, cat (in the small intestine)
Infection of this cestode causes G.I. disturbances and anemia. It causes megaloblastic anemia since vit B12 is absorbed by worm.
D. latum
The disease caused by drinking water containing infected copepods.
D. latum
Unarmed tapeworm of man
T. saginata
Adult worms are white and semi-transparent. It measures about 4-10 meters of sometimes up to 25 meters. It can live up to 10 years or more.
T. saginata
It consists of 1000 to 4000 proglottids. Its common genital pore is marginally situated. Its vagina is provided with a sphincter muscle. Furthermore, gravid proglottid consists of a uterus and a central longitudinal stem with 15-20 lateral branches
T. saginata
Its free gravid proglottid crawls out of the anal orifice and oviposits on the perianal skin
T. saginata
Liberated by rupture of ripe proglottids, no uterine opening, spherical and having a thin, outer transparent shell with its inner embryophore is brown, thick walled and radially striated
T. saginata ova
It has an oncosphere with 3 pairs of hooklets (inside the eggshell). It doesn’t float in saturated salt solutions and eggs are resistant and remain viable for 8 weeks.
T. saginata
FH & IH of Taenia saginata
FH: man
IH: cattle, cow buffalo
Its adult worm is irritated by alcohol
T. saginata
Pathogenesis of T. saginata (TaPaMi EHWW LPO)
Taeniasis
Passage of proglottids in stool
Mild irritation
Epigastric pain
Hunger pangs
weightloss
weakness
loss of appetite
pruritis ani
obstruction in intestine
Its eggs resemble kiwi slices
T. saginata
What is the treatment for T. saginata?
Praziquantel
This spp is common among those eating raw or insufficiently cooked “measly pork”
T. solium
Man can both be the DH/IH in this type of cestode.
T. solium
Scolex is globular in outline with 4 circular suckers. Scolex has a rostellum armed with a double row of alternating large and small hooklets. Rostellar hooklets are shaped like daggers or Arabian poniards.
T. solium
Vaginal opening is not guarded by a muscular sphincter.
T. solium
T or F. Taenia Saginata is infective to man as well as pigs.
False
Thick brown striated embryophere surrounding a hexacanth embryo.
T. saginata ova
Treatment for T. solium
Praziquantel
Also known as hydatid worm
Echinococcus granulosus
T or F. In Echinococcus granulosus, man harbors both the cyst and the adult worms which however is found in the intestine of dogs and canines.
False. it only harbors the cyst and not the adult worms
T or F. Echinococcus granulosus is compsoed of a scolex, neck and strobila having three segments – immature, mature, gravid.
True
Scolex bears 4 suckers and protrusible (can be extended) rostellum with 2 circular rows of hooks
E. granulosus
Ovoid in shape, resemble Taenia ova, Hexacanth embryo with 3 pairs of hooks
E. granulosus
E. granulosus is infective to:
man, cattle, sheep & other herbivorous animals
DH & IH of E granulosus
DH: dog, wolf, fox, jackal
IH: sheep, pig, cattle, horse, goat
Its most common site of involvement is the liver
E. granulosus
Its rupture of cyst in the lungs may present coughing accompanied by allergic reactions
E. granulosus
Echinococcus granulosus cyst
unilocular hydatid cyst
Echinococcus multicularis
alveolar cyst
What is the PAIR technique for inoperable cyst of E. granulosus?
Puncture, Aspiration, Injection, Reaspiration Invervention
Albendazole
3 testes in each mature segment. Uterus is sac-like and transverse. Eggs possess two membranes’ outer membrane is thin and transparent.
Hymenolepis spp
What is the larval syage of Hymenolepis spp.?
Cysticercoid
It has a small bladder containing the invaginated head proximally and a solid, elongated portion as a caudal appendage.
Hymenolepis spp
Smallest tapeworm infecting man
H. nana
Only human tapeworm that can complete its life cycle in a single host where man can harbor both the adult and larval stages of the parasite.
H. nana
This is found in the ileum & has a delicate strobila
H. nana
Subglobular, 4 suckers, provided with a short retractile rostellum armed with a single row of 20-30 hooklets where its rostellar hooklets are shaped like tuning fork.
Scolex of Hymenolepis nana
What differentiates H. nana & H. diminuta?
H. nana has polar filaments emating from little knobs at either end of the embryophore. Also, H. diminuta requires an intermediate host
H. nana has two mode of transmission. What happens during direct & indirect pathway transmission?
Direct: Host ingests eggs that hatches in the duodenum
Indirect: Accidental ingestion of infected arthropod IH like rice and flour beetles in which cysticercoid larvae are released and develop into adult worms in the small intestine of the host
Pathogenesis of H. nana (ImAH DAPA PD)
immunological response to the parasite
asymptomatic for light worm burden
headache
dizziness
anorexia
pruritus of the nose and anus
abdominal pain
pallor
dequamation
T or F. In H nana, proglottids are recovered because they undergo degeneration prior to passage.
False. They are not recovered.
Common parasite of rats and mice.
Hymenolepis diminuta
Larval stage of H. diminuta
cysticercoid passed in fleas
Outer shell is yellowish in color, inner embryophere has 2 knob-like thickenings, no polar filaments
H. diminuta
T or F. The longer the tail of H. diminuta, the more mature the cysticercoid.
true
This stage is found inside an insect such as the mealworm.
H. diminuta
Worm burden of H. diminuta in man
19
Common among children due to ingestion of infected grain beetles, dried fruits, flour and cereals
H. diminuta
Presence of bilateral genital pores in each segments (2 entrances)
Dipylidium caninum
Common intestinal parasite of dogs
Dipylidium caninum
Small and globular, 4 deeply cupped elliptical suckers, protrusible/retractile rostellum. Furthermore, rostellum has 1-7 rows of rose thorn shaped hooklets
D. caninum
Have size and shape of pumpkin seeds and is filled with capsules or packets of 8-15 eggs enclosed in embryonic membrane.
D. caninum gravid proglottids
Released by contraction of proglottids or disintegration outside the host. It is spherical, thin shelled, and with a hexacanth embryo.
D. caninum ova
1st IH of D. caninum and where they’re from.
Ctenocephalides canis
dog flea
1st IH of D. caninum and where they’re from.
Ctenocephalides felis
cat flea
1st IH of D. caninum and where they’re from.
pulex irritans
human flea
1st IH of D. caninum and where they’re from.
Trichoedectes canis
dog flea
2nd IH of D. caninum
Dog (cysticercoid)
Symptoms of D. caninum (SEDAA)
Slight intestinal discomfort
epigrastric pain
diarrhea
anal pruritus
allergic reactions
