Cestodes Flashcards
General characteristics of cestodes
- Dorsoventrally flat/ ribbon-like
- bilaterally symmetrical
- segmented
- hermaphroditic/monoecious
- no diget=stive tract
- adults must be found on intestines of definitive host
- intermediate hosts harbor larvae in extraintestinal sites
Cestodes are also called
Tapeworms
Hermaphroditic/monoecious means
Both male and female reproductive organs exist in the same organism
Cestodes acquire food through
Absorption with their tegument (skin-like covering)
The two anatomical region of cestodes
SCOLEX (anterior)
STROBILA (posterior)
This is located in the anterior most end of cestodes which may or may not contain hooks
Rostellum (Rostella)
Suckers are located in ___________ end and functions as ______________
Anterior; attachment and suction
Suckers in cestodes vary in shape:
Round/cup = ________
Groove = _________
Acetabulum
Bothrium
Each segment of a cestode is called
Proglottid
3 types of proglottid
Immature - repro organs are not yet fully developed
Mature - developed but not fertilized yet
Gravid/Ripe - uterus filled w/ ova
Segments emerge from the
Neck
Younger proglottids on cestodes are located
Near the neck
**Towards the end = gravid proglottid
Definitive host of intestinal cestodes
Human
Pork tape worm
Taenia solium
T. Solium infected stool samples demonstrates:
Egg or gravid segments
T/F: Extraintestinal infection of T. Solium is worse than taenia infection
TRUE.
Humans dead end host, larva die in muscle, lungs, brain, eyes = more severe manifestations
Number of acetabula on T. Solium
4
Scolex morphology of T. Solium
- 4 suckers (acetabula)
- rostellum w/ double crowns/rings of hooks
Describe immature proglottids of T. Solium
Wider than long
**Mature = becomes long
Part of T. Solum more visible in stool during diagnosis
Gravid proglottid
What dye is used to identify parts of mature proglottid?
India ink or methylene blue
To identify the proglottid as T. Solium, count the ________ from the base of the __________ branches
Uterine; uterine
How many lateral branches does T. Solium have for each side?
7-15 lateral branches
T. Solium infection shows ____________ in biopsy samples
Cystecerus cellulosae/larva (cysticerocis)
Most severe form of T. Solium infection
Neurocystecercosis
Which type of T. Solium infection is caused by the ingestion of insufficiently cooked/raw pork?
Taeniasis
T/F: Taeniasis can ause nutritional deficiency due to tapeworm’s competition to nutrients and irritation
TRUE
Extraintestinal infection of T. Solium
Cysticercosis
Cysticercosis of T. Solium can be acquired through…
Ingestion of contaminated food/drink w/ fecal material where ova is found = becomes accidental host
Diagnosis of taeniasis
Presence of proglottids, eggs, or scolex in stool
Beef tapeworm
Taenia saginata
Difference of T. Solium and T. Saginata in terms of its life cycle
Humans CANNOT serve as intermediate host for T. Saginata
Describe the scolex of T. Saginata
- cuboidal
- no rostellum, no hooks
- 4 cup-shaped suckers (acetabula)
T/F: T. Saginata has accessory ovarian lobe and vaginal sphincter
FALSE: it has NO accessory ovarian lobe
Number of lateral branches of T. Saginata
15-20
T. Saginata can be diagnosed through what procedure?
Perianal swab
T/F: T. Soilum is motile = it can migrate from intestine to perianal region.
FALSE: T. Saginata proglottid is motile
T/F: T. Saginata is larger than T. Solium
TRUE. It can be removed by surgery
Manifestations of T. Saginata infection
- epigastric pain
- hunger pangs
- pruritis ani
- intestinal obstruction
Fomerly known as T. Saginata subspecie asiatica
T. Asiatica
Number of lateral branches of T. Asiatica
11-32
What distinguishes cysticercus of T. Solium and T. Asiatica?
T. Asiatica has wart-like protruberances on the surface
Gravid segments of T. Solium and T. Asiatica is easily mistaken because…
Their lateral brances numbers overlaps
T/F: T. Asiatica does NOT produce cystocercosis in humans
True
Intermediate hosts of T. Asiatica
Swine
Cattle
Goats
Monkeys
Wild boar
Two important specie of genus hymenolepis
H. Nana
H. Diminuta
Dwarf tapeworm
H. Nana
Smallest tapeworm that can cause intestinal infection in human
H. Nana
Intermediate hosts of H. Nana
Arthropods: grain beetles, flour beetles (found in old stock of rice/flour)
Infection of H. Nana is acquired through….
Ingestion of food with cysticercoid larva
Which is being identified in stool for H. Nana infection?
Ova
**proglottids are rarely shed
_______ are more commonly found as parasites of rodents
H. Nana
Primary hosts of H. Nana
Rodents
Describe the scolex of H. Nana
- 4 acetabula
- armed rostellum
- Y-shaped hooklets
H. Nana has ______ testes and _____ ovary
3; 1 (single)
**gravid proglottid = testes and ovary disappear, uterus enlarge, compartments filled w/ ova
Distinguishable characteristic of ova of H. Nana
Two shells/membrance (thick inner/thin outer)
Severe immune reaction causes tissue necrosis by which cestode?
H. Nana
Rat tapeworm
Hymenolepis diminuta
Difference of life cycle between H. Nana and H. Diminuta
H. Diminuta REQUIRES intermediate host to complete life cycle
T/F: In terms of morphology, H. Diminuta has 8 hooks
H. Diminuta has NO hooks (unarmed rostellum)
Ova of H. Diminuta lacks _______
Bipolar filaments
**H. Nana has bipolar filaments
H. Diminuta Cysticercoid is found in __________
Intermediate host
Diagnosis of H. Diminuta is through detection of….
Eggs in stool
Dog tapeworm
Dipylidium caninum
Number of genital pores of D. Caninum
2 (Double-pored tapeworm)
T/F: D. Caninum is exclusive parasite of dogs
FALSE. Cats can also serve as definitive host
In D. Caninum, adults are found in ____________. While larval stage (cysticercoid) is found in ____________.
Intestines of definitive host;
Arthropods as intermediate host
Cestode with armed rostellum w 1-7 rows of hooklets (Rosethorn-shaped/broad base)
Dipylidium caninum
Pumpkin seed shape proglottids
D. Caninum
Dipilydium caninum proglottids appears….
Pumpkin seed shape
Double pores at each side (bilateral genital pores)
2 sets of reproductive organ per proglottid/segment
When ova are seen in D. Caninum infection, it appears as…..
Egg packets/capsules
Diagnosis of D. Caninum
Proglottids in stool
Egg capsules (rare)
Raillietina garrisoni definitive hosts
Rodents
R. Garrisoni intermediate hosts
Arthropod vectors
Parasite w/ hammer shaped hooks
R. Garrisoni
R. Garrisoni scolex morphology
4 acetabula
Armed rostellum
Hammer shaped hooks
Spines surround the rostellum
Rice grain proglottid
Raillientina garrisoni
Fish tapeworm
Diphyllobothrium latum
In terms of sizes, in cestodes, _________ next to Taenia is large
Diphyllobothrium latum
D. Latum is acquired through…
Ingestion of undercooked/raw fish
*Larva emerge and attach to intestinal walls = becomes adult
Scolex of D. Latum appears…
Spoon shaped/spatulate/leaf/almond
2 grooves (bothria)
The genital pore of D. Latum is (dorsal/ventral)
Ventral
Gravid proglottid appears _________ when stained since it is filled w/ ________
Black; eggs
Uterus of D. Latum is ____________
Rosette-like/coiled
T/F: The ova of D. Latum has abopercular knob and opeculum
TRUE
Vitamin B12 deficiency that leads to megaloblastic anemia can possibly caused by……
Diphyllobothrium latum
Diagnosis of D. Latum
Egg in stool
Proglottid in stool (RARE)
Extraintestinal cestodes are:
Echinococcus granulosus
Echinococcus multilocularis
Smallest tapeworms (smaller than H. Nana) associated w/ human disease
Echinoccus granulosus
Echinococcus multilocularis
Definitive host of Echinococcus spp.
Canines (Domestic/wild)
Intermediate hosts of Echinococcus spp.
Grazing ruminants (Herbivores that chew the cud/grass, sheep, goat)
T/F: Echinococcus spp. travels to the visceral organs (lungs/liver)
True
Echinococcus spp.’s accidental intermediate hosts:
Humans = dead end
Echinococcus spp. adults morphology
3 segments
Clinical manifestations of Echinococus spp. infection
Organ impairement, atrophy, necrosis, *depend on location of cyst (liver, lungs, brain, orbit)
Diagnosis of Echinococcus spp.
Microscopy (optional)
Imaging
Surgery - confirmatory
Serology
Sparganosis is caused by…
Spirometra spp.
Most common spirometra spp.
S. Mansoni
Previously thought to be D. Latum
Spirometra spp.
Spirometra species
S. Mansoni
S. Erinacei
S. Ranarum
T/F: Spirometra spp. and D. Latum infections has the exact life cycle
FALSE. Same but humans are NOT definitive hosts of Spirometra spp.
Modes of transmission on humans of Spirometra spp.
Ingestion of contaminated water
Ingestion of 2nd intermediate host
Infected intermediate/paratenic host applied on skin (poultice for sores)
Ingestion of flesh of paratenic host
Clinical manifestation of Spirometra spp.
Swelling (larva in tissue)
Painful edema
Erythema
Urticaria
Fever/chills
Eosinophilia
Diagnosis of spirometra spp.
Larva in lesion thru biopsy/actual extraction of larva from sore
