[Micro] cestodes

TAPE WORMS CESTODES
CLASS: Cestoidea
ORDER: Pseudophyllidea
Cyclophyllidea

GENERAL CHARACTERS
• Segmented
• Tape-like
• Compressed dorso-ventrally
• Few mm---several metres
• Live attached to mucosa in SI: absorb food
• DISEASE : DIPHYLLOBOTHRIASIS

ADULT WORM
• Scolex: organ of attachment only. No nutrition
• Muscular organ
• No suckers
• Pair of longitudnal grooves: bothria
• Rostellum: apical protrusion; present/absent
• hooks+/-
• NECK: behind scolex
• body generates

strobilia
• Body: no GIT. nutrients absorbed by integument
• Chain of segments
Types:
• immature…...... near neck; undifferentiated
• mature……… ….. larger; hermaphrodite
female/male reproductive systems
• Gravid: furthest away:
atrophied primary genitalia
uterus full of eggs

EGG
• Ovoid
• Operculated
• embryo formed later on: six –hooks;
hexacanth; called oncosphere
• Two coverings of embryo
• 1. embryophore
• 2. outer thin egg shell

Life cycle
• 2 hosts needed (except H nana; one host)
• Definite Host: MAN
• (except E granulosis; dog is definite host, man
intermediate)
• Intermediate host: mammals, fish ,arthropods
• one or two; harbor larvae

PATHOGENICITY
• ingestion:
• egg or larvae in food, water, fish, meat
• No damage to host except mechanical
obstruction in heavy infection; diarrhea, loss
of appetite, vitamin deficiency
• Cysts/ larvae in vital tissues pose risk like
brain, liver, lungs

LAB DIAGNOSIS
• Faeces: eggs, proglottidis
• Extra-intestinal: biopsy, serology, radio-image
Prevention:
• Avoid : raw food, contaminated water
• Protect community: safe disposal of human
faeces
• Avoid: animal contact

DIPHYLUOBOTHRIAM LATUM
• FISH TAPE-WORM
• Endemic: Northern hemisphere. Europe, Russia,
Japan, tropical Africa, Americas; Asia; not India,
Habitat:
• SI: jejnum or ileum of man
• Dog, cat, fox & fish eating animals
• Size: longest tape worm; 10 metres length
• 3000 or > proglottids

MORPHOLOGY….contd
• colour; IVORY
• Scolex: almond-shaped; spoon shaped
length; 2-3mm & 1mm width
• Grooves: 2 slit-like grooves with lateral lips
• No rostellum/hooklets
• Neck: thin, unsegmented,
several times head length

STROBILIA
• 3000 segments
• Mature: 10-20 mm……broad
2-4 mm…… long
• Eggs: periodic discharge via uterine pore
• Upto 1 million eggs daily in lumen of SI in
immature stage; mature in 1-2 weeks
• Terminal proglottids : hence empty
• Terminal segments dry, break-up and discharge in
faeces

EGG; not infective to man
• Yellow-brown; Oval; elliptical
• 70um length* 45um breadth
• Mass of granulated yolk cells surrounding an
undeveloped ovum
• Shell; thin, smooth
• Contains immature embryo
• Inconspicuous operculum at one end
• Small knob at other end
• Saturated solu. of common salt : does not float

TRANSMISSION
• Ingestion of infective larvae ie plerocercoid
In raw /insufficiently cooked fish as trout,
perch, pike
• larvae attach to wall of SI; in 2-4 weeks
develop into a mature tape worm
• EGGS are laid in lumen of intestine and passed
in feces; eggs are operculated & immature
• Fresh water: eggs hatch in 1-2 weeks

CORACIDIA: released ; spherical, ciliated
embryos with 3 pairs of hooklets
• CRUSTACEANS: ingest these
• Genus Cyclops/ Diaptomus
PROCERCOIDS: elongated larval forms develop in
few weeks
• FISH: eat the crustaceans and procercoids
develop into
PLEROCERCOIDS: these migrate to muscle &CT of
fish

LARVAL STAGE
• First: coracidium; in water
• Second: procercoid; in cyclops : & Diaptomus
In first intermediate host
• third stage: plerocercoid; develops in fresh-water
fish; second intermediate host
• Plerocercoid larvae: or SPARGANUM
• white, tape-like
• 10mm*2mm
• Fully developed: head with sucking grooves

LIFE CYCLE…contd
• completed by definite host eating fish
• Definite host: live for years
• human
• Animals: dog, cat, bear, fox, leapords
SYMPTOMS
GIT, weight loss, weakness, toxin-related
B 12deficiency: if in jejunum: megaloblastic
anaemia

PREVENTION
• FISH: Avoid raw fish intake esp. Smoked/
pickled
Kill pleros in fish by brine saturation,
freeze -10 C for 24-48 hrs
Prevent feeding dogs by fish offals
Latrine provision: eggs do not reach waters
• Maintains endemic state
• HEALTH EDUCATION

LABORATORY DIAGNOSIS
Faeces
• Eggs: 70-45um,oval,yellow with operculum
Yolk, ovum. Do not float in saturated saline
• Segments of worms
• Rare as disintegrate in intestine
• Shrunken, empty of eggs
• Undamaged mature segments 10-20 mm *3-
7mm with central pore.

ECHINOCOCCUS GRANULOSUS
• DOG TAPE WORM
• MAN ; Echinococcosis
• hydatid disease/hydatidosis
• FAMILY: Taeniidiae of Cyclophyllidiae
• DISTRIBUTION: world-wide
• Sheep, dogs, humans
• dogs/wild carnivores; livestock
• Africa; east, north, south, India, Mediterranian,
Mid-east, south America, Australia

TRANSMISSION
ZOONOSIS:
• Food/ hands contaminated with dog feces
• Intermediate host:
Sheep, cattle, pigs, camel
• Egg ingestion: by intermediate host
• Embryos: released in duodenum
• Penetrate intestinal wall and enter blood
vessels to liver, lungs, other organs

HYDATID CYSTS
• EMBRYOS develop to hydatid cyst
• Proto-scoleces develop in it
• Infected animal tissue of sheep eaten by dog, fox,
wolves
• In dog or definite host:
Scoleces evaginate, attach to SI wall, grow worm
Mature worm: 9mm long; 3-4 segments
Scolex: 4 suckers; crown of 2 rows of hooks

EGGS
• Produced & released by detached gravid last
segment on rupture
• Highly resistant eggs; survive long
• d/d: taenia
• MAN: dead end host as not eaten by animals;
occasionally feed on human remains
• Eggs: ingested….embryos freed in SI, enter BV
to blood….liver, lungs, bones , joints

HYDATID CYST
• EMBRYOS embed in tissues
• Few days….sac-like structures
• Few months/years…..hydatid cyst
HYDATID CYST
1.Outer thick laminated cyst wall
2.Inner thin , nucleated germinal layer
3. Brood capsules from inner wall
4.Germinal layer detached, will form daugter cysts

• Brood capsules: break off & sink down
through cyst fluid.
• Hydatid sand:
• Freed brood capsules
• Individual protoscolece
• Host response: fibrosis, calcification

Clinical features
FATE:
• Rupture of cyst: anaphylactic shock
• Cysts: grow for short time, die, calcify.
SITE & SIZE:
• Liver: 60% right lobe of liver
• Lungs: pulmonary symptoms;
sputum: blood, cyst fluid
Bone: pain on expansion; fracture
Rare: brain, kidney, spleen

PREVENTION
• Personal hygiene: hand wash after pet
handling
• Animal handling care: pets, herdsmen
• De-worming of dogs regularly
• Stray dogs: eliminate
• Uncooked offal/ meat : not fed to dogs
• Dog entry banned in slaughter houses
• Inspection of caracases

LAB DIAGNOSIS
• Clinical
• Ultra-sound
• Serum: anti bodies
• Surgical removal of cyst: do not puncture
examine for brood capsules, protoscoleces
• HISTOLOGY
PAS: laminated membrane
ZN: hooks of protoscoleces

Cyst fluid
• Let settle by gravity
• Centrifuge
• Deposit….make slide
• Protoscolex: colour-less, round/oval
• invagination, hooks

D/D Hepatoma
• Serum
• Glyco-proteins
• Amino-transferases
• Other LFTs
• Normal in Hydatid but increased in hepatoma
• ESR: marked increase in hepatoma
• moderate in hydatid

CASONI’S TEST
• Intra-dermal
• No standardization of Ag, technique,
interpretation
• Non specific
• False positive

SEROLOGICAL DIAGNOSIS
• SITE DEPENDANT:
• Liver: more sensitive than lung
• False negative:
• Calcified cyst
• Circulating immune complexes
• Indirect heme-agglutination test

ECHINOCOCCUS MULTILOCCULARIS
• Multi-locular OR Alveolar hydatid disease
• Canada, Alaska, USSR, Europe
• Definite host:
• Fox, wolves
• Inter-mediate: rodents, voles
• Man: accidental intermed host; ingest eggs
• LIVER: invasive, spreads like malignant tumor,
cavities, & necrosis; no capsule like hydatid
• FATAL; usually

FAMILY TAENIIDIAE
• Taeniasis
• Human definite host
• Taenia saginata
• Taenia solium
• Taenia asiatica
DISTRIBUTION
World-wide; mass travel; Africa, America, Asia
inadequate sewage disposal
Cattle, beef-eating
Camel: Morocco, Egypt

Life cycle
• T saginata:
• Transmission: eating raw, inadequately cooked
beef, meat with cysticercus larvae
• After digestion, the head is freed & attaches
to the wall of SI by its suckers.
• Segments (proglottides)are added from neck
downwards in 2-3 months. Long tape-worm
with gravid segment at tail end also found.

MATURE WORM
• Length: 4-10 metre
• Segments: 2000
• Scolex: cubical, 2mm across, 4 suckers
• Single worm usually; multiple rare
• Fully developed gravid segments become
detached, rupture to release eggs in feces
• Gravid segments may travel to peri-anal area
to discharge eggs

• Eggs have to reach grazing sites to access cattle.
• Segments may migrate to lands, disintegrate &
release eggs…mature/immature
• Mature eggs survive for months on lands.
• Each segment has 80,000 eggs
• After ingestion by cows, embryos are released by
eggs, pass intestinal wall, enter BV to reach
muscles where they grow to cysticerci larvae:
survive for months; calcify
• Embryos lose hooklets in muscle

CLINICAL FEATURES
• Abdominal pain
• Intestinal disturbances
• Loss of apetite
• Migrating segments: appendicitis, choleangitis,
• Pruritis ani
PREVENTION:
Avoid eating raw meat
Cysticerci larvae: Cook at 56 C, freeze 3 weeks
Meat inspection

Latrines: provision
Feces: containment, kill eggs/segments
do not use as fertilizer in pastures
Treat infected personel
Health education

LAB DIAGNOSIS
• Segment: passed singly; expelled on T/M
• recovered from clothing/feces
• Eggs: round/oval
• 33-43 um in diameter
• yolk cells
• embryo with hooklets: Acid fast
Embryophore: thick, brown, radially striated
Clear membrane/ egg shell: surrounds egg.
lost on segment disintegration

SEGMENTS
• White & Opaque
• Movement: move by muscle contraction;
• keep in closed container;
• use forceps for handling
• Wash with water, let soak if dry.
• Press bet. two slides & hold with tape/ band
• Immerse in formol saline for10 min to kill eggs
• Look in light for uterus, branching. Mature
imp

GRAVID SEGMENT
• White, opaque
• 20mm*6mm(longer than T solium)
• 13 side branches of main stem (T solium less)
SCOLEX
Small; 2mm
4 suckers
No hooks( d/d T solium)

TAENIA SOLIUM
• Less widely distributed
• Africa, China, India, Central America, Pakistan
• Human feces reach pigs, pork eaten
raw/under-cooked
• Tape worm: 2-3 metres length
• segments: 800-1000
• Scolex: round, 1mm
• 4 suckers, crown of hooks on two rows

infection
• One
• Multiple
• Both taenias
• 30,000-50,000 eggs
• Pigs ingest viable eggs, infective cystecerci in
muscles, embryonic hooklets lost

T solium
• Human host by food, contaminated fingers.
• Gravid segments regurgitated in stomach
• Cystecerci deposited in muscles, s/c tissue,
brain, sc, eyes
• Brain: epilepsy
• X rays: calcified cysts

[Micro] cestodes

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[Micro] cestodes