Cestodes Flashcards
Consists of a hexacanth embryo also known as oncosphere
Eggs
____ the motile, first larval stage characterized by the presence of six small hooks called ______
- oncosphere
- hooklets (arranged in pairs)
______
• Resemble a ribbon in appearance
• Very primitive that they absorb nutrients and excrete waste products through their outer surface, called ______
- Adult tapeworm
- Tegument
Distinct features (3) common to all adult tapeworms:
- SCOLEX
- NECK REGION
- A SERIES of PROGLOTTIDS referred to as the STROBILA
Scolex contains:
- Four cup shaped, known as suckers
- Rostellum
provide the worm the ability to attach to the intestinal mucosa of the infected host
Suckers
a fleshy extension of the scolex, from which none, one or two rows of hooks might be present
Rostellum
Beef tapeworm
Taenia saginata
Pork tapeworm
Taenia solium
Is also associated with CYSTICERCOSIS
T. solium
is found worldwide
T. solium
is found primarily in cosmopolitan areas
T. saginata
Taenia spp. EGGS
It is surrounded by a _______ present on select tapeworm eggs known as ______ on which distinct radial striations reside.
- yellow brown shell
- embryophore
Primary difference between T.saginata and T.solium
T. solium contains a
fleshy rostellum and a row of double crown(hooks), T. saginata lacks
these structures.
*Taenia spp. PROGLOTTIDS
Taenia saginata
Average number: ____
Appearance:____
No. of uterine branches:____
Average number:1048
Appearance: rectangular
Size: 17.5 by 5.5 mm
No. of uterine branches: 15 to 30
*Taenia spp. PROGLOTTIDS
Taenia solium
Average number: ___
Appearance: ___
No. of uterine branches: ___
Average number: 898
Appearance: square
No. of uterine branches: 7 to 15
Infection follows after ingestion of raw or undercooked beef (T.saginata) or pork
(T.solium) contaminated with ___
cysticercus larva (intestinal taeniasis)
is a larva that consists of a scolex surrounded by a bladder-like, thin-walled cyst that is filled with fluid
Cysticercus larva
Two types of cysticercus larva
- Cysticercus bovis: Taenia saginata
- Cysticercus cellulosae: Taenia solium
Taenia spp life cycle
larva emerges in the ___ , where maturation into adult worm occurs.
small intestine
Taenia spp. IH
Cow (saginata)
Pig (solium)
*Cysticercosis
common manifestation
neurocysticercosis
Taenia spp. LABORATORY DIAGNOSIS
- Specimen of choice:
- Has a very high rate of recovering
Taenia eggs: - Since the eggs are highly identical, recovery of ____ is a must to speciate them:
- Immunologic tests for Cysticercosis:
- STOOL
- CELLOPHANE TAPE PREP.
- GRAVID PROGLOTTID OR SCOLEX
- IHA and ELISA
TAENIA SPP. TREATMENT
*Treatment of choice:
* Alternative treatment:
* Cysticercosis:
- PRAZIQUANTEL
- PARAMOMYCIN and QUINACRINE HYDROCHLORIDE (ATABRINE)
- SURGICAL REMOVAL and MEDICATION
contains a SUNKEN ROSTELLUM AND TWO ROW OF HOOKLETS
Taenia asiatica
RAT TAPEWORM
Hymenolepis diminuta
Distributed worldwide especially
in areas in which foodstuffs such
as grain or cereal are not
protected from rats and insects.
Hymenolepis diminuta
- Average size: 55 to 85 um
- The hexacanth embryo contains
three pairs of hooks - A shell surrounds the embryo that
exhibits distinct polar thickenings
and no polar filaments. - A colorless embryophore encloses
the entire structure.
Hymenolepis diminuta Eggs
- Equipped with four suckers
- a rostellum bearing no hooks protrudes
from the anterior end of the scolex
H. diminuta Scolices
H. diminuta infective stage to humans
cysticercoid larvae
- Each mature segment contains one set
of female and one set of male
reproductive organs. - The gravid proglottid which is twice as
wide as long, consists of a saclike uterus
filled with eggs that occupy most of the
available space.
H. diminuta Proglottids
H. diminuta
Treatment of choice :
Alternative:
- Praziquantel
- Niclosamide
“dwarf tapeworm”
Hymenolepis nana
- Considered to be the most common
tapeworm recovered in the United
States. - Tropical and subtropical climates harbors
this parasite
Hymenolepis nana
- Has a shell complete with polar thickenings that protect the embryo
- Numerous polar filaments originate from the polar thickenings
Hymenolepis nana Eggs
- Contains four suckers
- Short rostellum with one row
of hooks
H. nana Scolices
- Mature and gravid proglottids
resemble those of H.diminuta
both in size and appearance
H. nana Proglottids
H. nana
Development of the cysticercoid larva occurs in the ____
intestine
resides in the intestine, in which it is capable of self-reproduction
H. nana adult worms
commonly found in grains
that may serve as intermediate host for
Hymenolepis spp.
Tribolium beetles
H. nana
Drug of choice:
Alternative:
- Praziquantel
- Niclosamide
Dipylidium caninum is also known as
“dog or cat tapeworm”
“pumpkin seed tapeworm”
- Commonly associated with
Dipylidiasis, dog or cat tapeworm
disease - Distribution is worldwide.
- Children are at the highest risk for
infection transmission.
Dipylidium caninum
- Consists of typical six-hooked oncosphere.
- Form a membrane-enclosed packets which may contain 5 to 30 eggs per packet.
Dipylidium caninum Eggs
- Conical in shape with four suckers
and a club-shaped retractable
rostellum armed with one to six or
seven circlets of spines (rose-thorn
shaped) instead of hooks.
D caninum
- The mature and gravid proglottids resemble pumpkin seeds in shape
- Each mature segment contains two sets of both male and female
reproductive organs
Dipylidium caninum Proglottids
- Accidental human infection happens upon ingestion of an intermediate
host’s dog or cat fleas
Dipylidium caninum
- The fleas may be transmitted by a lick of the infected dog or cat or by
hand-to-mouth contamination or ingestion of contaminated food.
Dipylidium caninum
Patients may also experience anal pruritis
caused by migrating gravid proglottids to the anus.
Dipylidiasis: Dog or Cat Tapeworm Disease
H. caninum diagnosis
recovery of egg packets or gravid
proglottid in stool samples
H. caninum
Treatment of choice:
Alternatives:
- Praziquantel
- Niclosamide and Paramomycin
“broad fish tapeworm”
Diphyllobothrium latum
Diphyllobothrium latum is also known as
Dibothriocephalus latus
- Found in a variety of temperate regions worldwide
- Noted endemic areas include parts of South America and Asia, Central Africa, the Baltic region, and Finland where raw and/or freshwater fish are routinely consumed. Also found in Alaska and the Great Lakes in US.
Diphyllobothrium latum
- Consists of a ciliated larval stage known as
coracidium, surrounded by a smooth yellow
to brown shell. - Operculum, which is a lid structure,
consumes one end of the egg - Abopercular knob is a small but distinct
terminal knob which extends from the
opposite end of the egg.
D. latum eggs
Almond in shape and contains
two long, prominent, sucking
grooves.
D. latum scolices
- Wider than they are longer
- Characteristically contain a
centrally located uterine structure that frequently assumes a rosette formation.
D. latum proglottids
H. latum
Human infection is initiated upon ingestion of ____
pleurocercoid
a precursor larval stage, contaminated freshwater fish that is raw or undercooked.
pleurocercoid
D. latum
First intermediate host:
Second intermediate host:
- Cyclops
- Freshwater fish
D. latum
_____ may develop when the adult worm takes up residence in and attaches itself to the proximal part of the jejunum. This condition mimics that of Pernicious Anemia.
Vitamin B12 deficiency
This condition results from ingesting the procercoid larvae of Diphyllobothrium latum.
Sparganosis
an infected subcutaneous tissue often described as white, wrinkled, and ribbon-shaped, typically results
Sparganum
Humans can contract Sparganosis in two ways:
- Through water contaminated with infected copepods.
- Through medicines contaminated with infected animal by-products.
H. latum
Drugs of choice:
Sparganosis:
- Praziquantel and Niclosamide
- Surgical removal of sparganum ( treatment with praziquantel is also effective)
Echinococcus granulosus is also knwon as
“dog tapeworm” “hydatid tapeworm”
causes cystic echinococcus and is most frequently encountered
Echinococcus granulosus
is associated with alveolar echinococcus which is becoming more common
E. multilocularis
Within the hydatid cyst of E. granulosus, miniaturizations of the entire cyst may occur, and is referred to as
daughter cysts
components found in the
fluid of older E.granulosus cysts that typically
include daughter cysts, free scolices,
hooklet, and miscellaneous nondescript
material may evolve
Hydatid sand
E. granulosus scolex contains four suckers and has approximately ____ (not typically
seen in humans but in canines)
36 hooks
Serves as accidental intermediate hosts of e. granulosus
Humans
Enlargement of cyst leads to necrosis of the
infected tissues, accompanied by build up
of pressure on the site. Death may also
occur.
ECHINOCOCCOSIS/HYDATID DISEASE/HYDATIDOSIS
E granulosus lab diagnosis
- Hydatid cyst biopsy samples
- ## Serologic tests such as ELISA, IHA, and Western blot test
E. granulosus treatment
- Surgical removal of the hydatid cyst
- Mebendazole, Albendazole, and Praziquantel have been useful in
situations which the hydatid cyst was inoperable.
