Cestode.pdf

• Cestodes are hermaphrodite,
• Segmented endoparasites with an elongated dorsoventrally flattened (tape-like)
body without an alimentary canal.
• They come under the phylum Platyhelminthes and classified into two classes:
• Eucestoda (true cestodes) and Cotyloda (primarily cestodes of fish).
• A typical cestode usually consists of a head or scolex followed by a short
neck (unsegmented) and body or strobila (consists of chain of segments-
proglottids)
• The head or scolex bears four suckers as the organs of attachment which
may be armed with hooks.
• The scolex may have two long muscular grooves called bothria instead of
suckers (Cotyloda).
• A protrusible cone, called rostellum, often armed with hooks may be present in
the scolex.

• Neck is an unsegmented portion, situated just posterior to the scolex,
• which continuously produces proglottids (segments) by metameric
repetition of their reproductive organs, called proglottidization(Eucestoda).
• Strobila constitutes the main bulk of the body and made up of a chain of
immature, mature and gravid proglottidsor segments.
• Anteriorly situated proglottids without functional reproductive organs. are
immature
• These are followed by mature proglottids with functional reproductive
organs.
• After fertilization, all the reproductive organs slowly degenerate and the
proglottidsare occupied with eggs. These are then called gravid proglottids.
• After shedding of gravid segments, the eggs in gravid proglottids are
liberated either by disintegration of proglottids(apolysis)

• In cestodes, the basic body tissues are excretory, nervous and reproductive
systems. Alimentary system is absent in cestodes.
• The body wall of cestodes is made up of several layers of tegument
• which is highly absorptive and composed of a syncytial outer layer formed
by the tegumental cells.
• Under electron microscope, this outerlimiting membrane of the tegument
and containsnumerous structuressuch as mitochondria, golgi apparatus,
ribosomes, endoplasmic reticulumetc.
• The entire structureserves as site for absorption.
• Muscles lie beneath the syncytial layer and more deeply in the
parenchyma-filled body.
• They divide the body into outercortical and inner medullarysections. The
medullacontains the excretory, nervous and reproductive organs.

• Excretory system: Excretory system is also known as osmoregulatory
system (a nephridial system) which consists of flame cells and excretory
canals
• Reproductive system: Cestodes, being hermaphrodites, have both male
and female reproductive organs in each proglottid.
• There may be one or two sets of reproductive organs in each proglottid.
The reproductive organs generally mature from the anterior to the posterior
prolottids
• The male reproductive organs develop first. It includes testis, vas efferentia,
Vas deferens, cirrus sac.
• Female reproductive system- Vagina, ootype,Mehli,s gland, Ovary,
Vitelline gland, uterus

• In some species of Eucestoda, it may give rise to extensive side branching
(e.g. Taenia).
• In others, the uterus may degenerate and the eggs pass into protective
structures within the proglottids. These include hyaline egg capsules (e.g.
Dipylidium)formed by the uterus itself
• par-uterine organs, the dilatations of the uterus from the denser parenchyma
(e.g.Stilesia, Avitellina).Which exists after the uterushas been disappeared.
• All these structuresserve as protective envelope for the eggs.

• In cotyloda the proglottids are not detached and eggs are normally
continously discharged from the proglottids through uterine pore and when
egg production has stopped the proglottids are detached from the strobila
by psuedoapolysis
• Life cycle: General****
• Eggs may be embryonated or unembryonated when discharged from the
host.
• The eggs when become fully embryonated contain an oncosphere, which is
armed with six embryonic hooks, called hexacanth embryo (6 hooks).
During the development of eggs, four embryonic envelopes (capsule(egg
shell) outer envelope, inner envelope(Embryophore) oncospheral
membrane) may be seen.
• In Cotyloda: The egg is having a thin shell and operculum , close
relationshipwith trematode egg.

• In Cotyloda, the oncosphere which is, covered by ciliated embryophore,
called coracidium.****
• On ingestion, the oncosphere is released by the intermediate host probably
under the influence of digestive juice and digestive enzymes
• Inside the intermediate host, the oncosphere is activated by the host’s
stimuli and the activated oncosphere emerges from its oncospheral
membrane
• and penetrates the intestinal mucosa to reach its site of predilection for
further development.
• Cestodes, except Hymenolepis nana, have indirect life cycle. Their
different larval forms develop inside one or more intermediate hosts and are
collectively known as ‘bladder worms’ or metacestodes. These develop
both in invertebrates and vertebrates I.H
• In Eucestoda: The larval stages are Cysticercoid, cysticercus, Coenurus,
hydatid Cyst, strobilocercus, Tetrathyridium depending on the species of
parasite. In cotyloda:Procercoid/ Plerocercoid

• On ingestion of either whole of the invertebrate or body parts of vertebrate
intermediate hosts carrying the infective metacestodes,
• attach to the mucosa of intestine and grow to adult

Metacestodes/ bladder worms
• Cysticercoid:A pin-point sized vesicle with one scolex not invaginated
without a cavity (Solid) and develop in invertebrates (e.g. in oribatid mites
and otherarthropods, Eg: Moneizia expansa).
• Cysticercus:A bladder-likevesicle containingfluid into which one scolex
is invaginated and develops in striated muscles and other body parts of
mammals (Taeniasolium).
• Coenurus:A thin semi-transparent bladder,containingplentyof fluid with
a large number of scolices invaginated from the germinal layer (e.g. in the
Taenia multiceps.

Hydatid: A thick walled large sized bladder filled with fluid, producing brood
capsules from the germinal layer and, inside each brood capsule, a number
of scolices develop. (e.g. in different organs of ungulates and man;
Echinococcusgranulosus).****
• Strobilocercus: An evaginated scolex attached to a bladder by a segmented
strobila (e.g. Taeniataeniaeformis
• in livers of rodents).
• Tetrathyridium: A solid elongated larva with deeply invaginated
acetabular scolex (Mesocestoides spp.)

• In Cotyloda:
• Procercoid: A solid first larva which bears three pairs of embryonic hooks
in the cercomer in the posterior region (e.g. in the body of copepod
crustaceans; Diphyllobothriumlatum).
• Plerocercoid: It succeeds procercoid stage. It is an elongate solid-bodied
metacestode with a scolex like an adult (e.g. this larval form of D. latum
occurs in fresh water fishes).

Class Eucestoda Class cotyloda
The head or scolex bears four suckers as
the organs of attachment which may be
armed with hooks.
The scolex may have two long muscular
grooves called bothria instead of suckers
The eggs in gravid proglottids are
liberated either by disintegration of
proglottids (apolysis)
The proglottids are not detached and eggs
are normally continously discharged from
the proglottids through uterine pore and
when egg production has stopped the
proglottids are detached from the strobila
by psuedoapolysis
Radially striated embryophore is present On hatching the egg it will release the
oncosphere which is, covered by ciliated
embryophore, called coracidium.
Larval stages…. Larval stages- Procercoid/ plerocercoid
Non operculate egg : The egg is having a thin shell and
operculum , close relationship with
trematode egg.
Monezia expansa Eg: Diphyllobothriumlatum

Cestode Trematode
Segmented body Nonsegmented body
Tape like Leaf like/ conical shape
Alimentary system is absent Alimentary canal is present without anus
Non operculated egg except class cotyloda Operculated eggs
Larval stsges- Cysticercus etc.. Larvals tages- Miracidium, redia…
Miraciidium Coracidium
Ciliated larval stage in
trematode
Eg: Fasciola gigantica
Ciliated embryophore covering
the oncosphere formed after
the hatching of egg eg: Class
cotyloda

Differentiate…..
Cysticercoid Cysticercus
Cysticercus Coenurus
Hydatid cyst Coenurus

• CLASSIFICATION: Cestodes are classified under two Classes, Eucestoda
and Cotyloda.
• CLASS: EUCESTODA
• Family: Anoplocephalidae
• Genera: Anoplocephala, Paranoplocephala,Moniezia****
• Family: Thysanosomidae
• Genera: Avitellina, Stilesia, Thysanosoma, Thysaniezia
• Family: Davaineidae
• Genera: Davainea, Raillietina, Cotugnia*****
• Family: Dilepididae
• Genus : Amoebotaenia
• Family: Dipylidiidae
• Genera: Choanotaenia, Dipylidium,***** Metroliasthes

• Family: Hymenolepididae
• Genus : Hymenolepis
• Family: Fimbriariidae
• Genus : Fimbriaria

• Family: Taeniidae
• Genera: Taenia, Echinococcus****
• Family : Mesocestoididae
• Genus : Mesocestoides
• CLASS: COTYLODA
• ORDER: DIPHYLLIDEA
• Family: Diphyllobothriidae
• Genera: Diphyllobothrium,Spirometra****

FAMILY: ANOPLOCEPHALIDAE
• The uterus persists as transverse tube or network of tubes.
• Microscopic mites of the family Oribatidae act as intermediate hosts in
which cysticercoids develop.
• The cestodes are mostly the parasites of herbivores and are devoid of
rostellumand hooks in their scolices.
• Egg has three coverings – an outermost vitelline membrane, a middle
albuminouscoat, and an innermost chitinous membrane.
• It is generally pear-shaped, bearing on one side a pair of hooked projections
(the pyriform apparatus).

Genus Anoplocephala
• It is a large cestode with marked segmentation, parasitising intestine of
equines.
• There is single set of reproductive organs with numerous testes
throughout medulla in each proglottid.
• The ovary is lobed and transverselyelongated.
• Genital pore is unilateral.
• Vitellaria lie posteriorto ovary in median field.
• The eggs are present in the transverse elongated uterus, each possessing a
pyriform apparatus.

Anoplocephala perfoliata
• Commonly it is known as
‘lappetted cestode’ of equines as
there is a special structure, called
‘lappet’behind each sucker.
• It occurs in the large and small
intestine of horses and other
equines.
• Anoplocephala magna: It occurs in
the small intestine, and rarely in
stomach of horses and other
equines.
• Lapetts are absent.
• The scolex is larger than A.
perfoliata.

Genus: Paranoplocephala
• Paranoplocephalamamillana:
• It is commonly known as the
‘dwarf tapeworm of horse’.
• It occurs in the small intestine,
rarely in the stomach of the horse.
• Lapetts are absent

• A large number of species of orabitid mites act as intermediate host viz.,
Scheloribates latipes.
• These mites are commonly found on grass in grazing field.
• They eat upon eggs of tapeworms left in the defecated mass by the animals.
• Cysticercoidsdevelop in these mites after 2-4 month of their infection.
• The horse pick up the infection by ingesting infected mites during grazing.
• Adult tape worm develop in the intestinein 4 to 6 weeks.

Pathogenesis
• Scolices of A.perfoliata attach themselves deep into the mucosa of
intestine particularly near ileo-caecal orifice causing depressed ulcerative
lesions.
• Occasionally, there may be partial occlusion of ileo-caecal orifice due to
excessive growth of granulation tissue which may be one of the cause of
intussusception.
• In A.magna infection, there may be catarrhal or haemorragic enteritis in
the small intestine.
• In both the infection, perforation of the infection has been recorded in
heavy infection.
• P.mammillanais rarely pathogenic.

Clinical signs
• There is loss of appetite, poor body growth, unthriftiness,diarrhoea and
enlargement of belly.
• Animal may lie down and turn the head back.
• Perforation of the intestine often ends fatally.

Diagnosis
• Symptoms make sometime difficult to difficult to
differentiate from other causes.
• Diagnosis of infections of tapeworms in live horses is
difficult.
• Detection of their eggs in horse feces is not reliable by
standard techniques for determining presence of eggs of
other internal parasites, such as nematodes.
• Therefore, not finding tapeworm eggs in feces does not
mean these parasites are actually absent in a horse.
• Tapeworm eggs are angular and vary in appearance,
depending on the view presented.
• The eggs have hyaline-like thickened walls and contain
an embryo with six hooklets (hexacanth).
• Tapeworm infections can sometimes be verified by
finding specimens in feces after a horse has been treated
with a drug active against these parasites.

Treatment and Control
• Treatment for tapeworms includes only one compound (praziquantel) with
a label claim against these parasites.
• Praziquantel is marketed in combination with ivermectin and with
moxidectin.
• Trade names for these productsand restrictions for usage at this time are:
• 1. Equimax (ivermectin plus praziquantel) is approved for horses four (4)
weeks and older, including breedingmares and stallions.
• 2. Zimectrin Gold (ivermectin plus praziquantel) is approved for horses
five (5) months and older but NOT for breeding mares and stallions.
• 3. Quest Plus (moxidectin plus praziquantel) is approved for horses five (5)
months and older but NOT for breeding mares and stallions.

Genus: Moniezia
• Each proglottid is provided with two sets of
genital organs and usually with
interproglottidal glands.
• The species are commonly called ‘double-
pored tapeworms of ruminants’.
• Numerous testes are distributed mostly in the
central medullary field.
• Ovary and compact vitelline glands assume
like a ring on either side.
• Uterus is sac-like and occupies the entire
medulla.
• Eggs possess pyriform apparatus.
• Cysticercoids develop in orabitid mites, Adult
tapeworms are usually found in the intestine
of ruminants.

• Moniezia expansa and Moniezia benedeni: Both these tapeworms are
commonly found in the small intestineof different ruminants.
• M. expansa occurs more commonly in sheep and goat while M. benedeni
is generally found in cattle.
• The adult tapeworms may reach a length of 600 cm.
• The scolex is provided with only unarmed four prominent suckers.
• The proglottids are broader than long, each with two sets of reproductive
organs.
• The ovaries and vitelline glands look like a ring on either side of each
proglottid.
• Each proglottid at its posterior border is provided with a row of
interproglottidal glands.
• In M. expansathey extend along the full breadthof the proglottid.

Proglottid Moniezia expansa and Moniezia
benedeni
In M. expansa they extend along
the full breadthof the proglottid.
In Monezia benedeni the interproglottidal
glands are arranged in a short, continuous row
close to the mid line of segment.

• In Monezia benedeni the interproglottidal glands are arranged in a short,
continuousrow close to the mid line of segment.
• The eggs, are somewhat triangular in shape in M. expansa, somewhat
square in M. benedeni.
• Egg containsa well developed pyriform apparatus.

• Orabitid mites act as intermediate host.
• The infective cysticercoides develop in about 4 months.
• The definitive host get the infection by ingesting infected mites during
grazing.
• Animals start shedding gravid proglottids after 37-40 days of picking up
the infection

Pathogenesis
• Infection is usuallycommon in young animals under six months of age.
• In heavy infection, the intestine may be packed up with solid mass of
tapeworms.
• There may be obstruction of the intestine may be packed up with solid
mass of tapeworms.
• There is diarrhoea and unthriftiness.
• In lambs, depressed wool and meat production along with
enterotoxaemia and death in Monieziainfection have been recorded.

Diagnosis
• Infected animals pass loose dung along with ripe (gravid) proglottids
looking like cooked rice grains.
• Typical Moniezia eggs in these gravid segments and free in faeces confirm
the diagnosis.

Treatment
• Niclosamide is most often used.
• Praziquantel (while not approved for use in ruminants in the US) is also
99–100%effective while albendazole is 19-75%effective.
• Praziquantel + Levamisole combination is very effective in reducing worm
burden and improvement of weigh.
• Albendazole (10 mg/kg)

FAMILY: THYSANOSOMIDAE
• In tapeworms under this family the gravid uterus disappears and is
replaced in functionby paruterineorgans.
• Cysticercoids develop in psocopterousinsects.
• The important genera are Avitellina and Stilesia., Thysanosoma,
Thysaniezia

Genus: Avitellina
• It is long and narrow cestodeswith indistictsegmentation.
• There is set of genital organs.
• Genital pore are irregularly alternative.
• Testes occur in lateral field of each segment.
• Avitellinacentripunctata
• It is occurs in small intestine of sheep , goat and otherruminants in world.
• Strobila becomes almost cylindricalin shape at the posteriorend.
• Intermediate host: insect like book lice, bark lice and dust lice.

Genus: Stilesia hepatica
• Adult tapeworms are long and narrow, and commonly found in the bile
ducts of sheep, goat, cattle and other ruminants in Africa and Asia.
• There is single set of genital organs.
• Vitelline and shell glands are lacking.
• Uterus first appears as long transverse, dumb-bell shaped tube and later
replaced by two paruterineorgans.
• Eggs are without a pyriform apparatus
• Stilesia globipunctata: It occurs most frequently in the small intestine of
sheep, goat, cattle and other ruminants.
• Stilesia vittata:Found in camel, cattle, goat and sheep in India.
• Oribatid mites act as intermediate host.

Genus: Thysanosoma
• Thysanosoma actinioides:
• It is commonly called ‘fringed
tapeworm’ of ruminants.
• It occurs in the bile ducts,
pancreatic ducts and small
intestine of sheep, cattle and other
ruminants in America.
• The segments are short and
distinctly fringed posteriorly.
• This is another double-pored
tapeworm of ruminant besides
Moniezia spp. having two sets of
genital organs.
• Pyriform apparatus is absent in
eggs.
• Par uterine organ is present.

Genus: Thysaniezia
• Thysaniezia giardi:
• It occurs in the small intestine of sheep, goat and cattle.
• It is rarely seen in animals in India.
• Eggs pass from the uterus into a large number of small paruterine
organs. There is no pyriform apparatus in eggs.
• Possibly, psocids and oribatidmites act as intermediate hosts.

Pathogenesis
• In stillesia gobipunctata infection, the scolices of a large number of
immature tapeworms penetrate deep into the mucosa of the initial part of
small intestine (duodenum and jejunum) causing severe nodule
formation,proliferation inflation and cellularinfiltration.
• Avitellinaspp. And S. Hepaticaare considered non pathogenic.
• In heavy infection also the affected animals do not show clinical
symptoms although bile duct may be occluded and from sac like
dilatations filled with cestodes.
• There may be slight cirrhosis of the liver.

Treatment and Control
• Praziquental: 10-15 mg/kg bw orally.
• Niclosamide 75-100mg/kg.
• Controlof tapeworms is difficultbecauseof a large number of grass mites
are spread all over the grazing land.
• Ploughingand reseeding the pastures or avoiding use of use of infected
pastures for consecutive year may help in controllingthe infection in
young animals.

FAMILY: DAVAINEIDAE
• The rostellum is armed with one or more circles of
hammer-shaped hooks.
• In gravid proglottids eggs are enclosed in egg
capsules.
• Genus: Davainea
• Davainea proglottina: It measures 0.5-3 mm in
length, smallest and most pathogenic species of
poultry cestodes
• Both rostellum and suckers are armed with hooks.
• Molluscs such as Limax, arion, Agriolimax (Slugs
and snails) act as intermediate hosts
• Genus: Raillietina
• Rostellum is armed with 2 rows of hooks
and encircled by several rows of minute spines.
• Suckers may also be armed with several circles of
hooks.

• Raillietina tetragona: It is commonest tapeworm of fowl and occurs in the
small intestine of gallinaceousbirds throughoutthe world.
• It is the largest species of tapeworms in birds and reaches up to 25 cm in
length.
• The suckers are oval /elliptical
• There are 6-12 eggs in each egg capsule
• Ants of the genera pheidole, Tetramorium and Monomorium are the
intermediate hosts.
• Raillietina echinobothrida: It occurs in the small intestine of chicken,
turkey and pigeon in most parts of the world
• Suckers are circular bear 8-12 circles of hooks
• ants – I.H

Railletina tetragona
Railletina echinobotrida

Railletina echinobothrida Railletina tetragona

• Raillietinacesticillus:It occurs in the small intestine of poultry.
• Beetles- I.H
• Raillietina assamensis: A common cestode occurring in the posterior part
of intestine of fowl in eastern India.
• Genus: Cotugnia
• There are two sets of genital organs in each proglottid.
• Cotugniadigonopora:It occurs in the small intestine of fowl
• Each proglottid possesses two sets of genital organs
• The species is commonly called ‘double-poredtapeworm of poultry.
• I.H – Ants

FAMILY: DILEPIDIDAE
Tapeworms are parasites of birds.
• Genus: Amoebotaenia
• Tapeworms are small in size.
Rostellum is bottle-shaped with a single
crown of hooks.
• Proglottids increase in length and
width posteriorly. One set of
reproductive organs is present in each
proglottid.
• Species are parasites of birds.
• Amoebotaenia cuneata (A.
sphenoides): It occurs in the small
intestine of domestic fowl. It is small
and roughly triangular in shape,
• Earthworms of the genera Eisenia,
Pheretina, - I.H

Poultry cestodes Intermediate host
Davainea proglottina Molluscs such as Limax, arion,
Agriolimax (Slugs and snails
Raillietina tetragona Ants of the genera pheidole, Tetramorium
and Monomorium
Raillietina echinobothrida ants – I.H
Cotugnia digonopora Ants
Amoebotaenia cuneata Earthworms of the genera Eisenia,
Pheretina
Choanotaenia infundibulum: Musca domestica-
Raillietina cesticillus
Hymenolepsis carioca
Hymenolepis lanceolate:
Beetles
Beetles
cyclops

Pathogenesis of poultry cestodes
• Davainea proglottina is the most pathogenic poultry tape worm. The
cestodes penetrate deeply into the villi and cause necrosis and
haemorrhagic enteritis.
• Of the Raillietina species, R. echinobothrida is most pathogenic since the
parasite forms various nodules at the site of attachment in the
intestine.(Nodulartape worm of poultry)
• Of the Hymenolepisspecies, H. lanceolateis most harmful cestode.
• Other species of cestodes are not usually harmful but in extremely heavy
infections they may cause decreased production.
• Poor management is responsible for high incidence of tapeworm infection
in poultry due to availability of a large number of ants, beetles, house files
etc. in and around poultryhouses.

FAMILY: DIPYLIDIIDAE
• The gravid uterus is replaced by egg capsules containing
one or more eggs.
• Genus Dipylidium, Chanotaenia
• Genus: Dipylidium caninum
• It is most common and cosmopolitan parasite of dog,
cat, fox and occasionally children.
• There are two sets of genital organs in each proglottid.
The species is commonly called ‘double-pored
tapeworm of dog’.
• Rostellum is retractile, with several crowns of rose
thorn-shaped hooks.
• The ovary and vitelline glands form a mass on either
side of the proglottid resembling a bunch of grapes.
• Testes occupy the entire proglottid.
• Each egg capsule may contain up to 30 eggs.
• Mature and gravid proglottids have a characteristic
elongate shape resembling cucumber seeds

Life-cycle
• Infected dogs pass gravid segments through faeces
• or they may leave the host spontaneously and crawl about actively
disseminating eggs.
• The intermediate hosts are dog fleas (Ctenocephalides canis, or other
C.felis or Pulex irritans), and dog louse (Trichodectescanis).
• Larval flea and louse ingest eggs and cysticercoids develop in the adult
insects.
• The definitive hosts are infected by swallowinginfected flea and louse.

Diagnosis
• Presence of typical gravid proglottidsin faeces of infected animals.
• The characteristic egg capsule contain up to 30 eggs.

Genus: Choanotaenia
• Choanotaenia infundibulum: It occurs in the
small intestine of fowl and turkey.
• The eggs have distinct elongate filaments.
• House fly, Musca domestica-I.H
• Genus: Metroliasthes
• Metroliasthes lucida: It occurs in the small
intestine of fowl and turkey in India, North
America and Africa.
• Grasshoppers of the genera Melanoplus,
Chorthipus and Paroxya, serve as intermediate
hosts.

FAMILY: HYMENOLEPIDIDAE
• Genus: Hymenolepis
• The cestodes are usually narrowand thread-likein appearance.
• Proglottidsare usually numerous.
• Testes are 3 per proglottid.

Hymenolepis nana
• It is commonly known as ‘dwarf tapeworm’ of rodents, simian primates
and man.
• Direct life cycle.
• Life-cycle: In man, it is direct and the cysticercoids develop within the villi
of the small intestine.
• There may be self-infection through ingestion of eggs containing the
developing cysticercoidsdischarged with own faeces.
• There may also be auto-infection where the cysticercoids while in the
intestine hatch out from the eggs and attach to the mucosa to grow into
adult tapeworms.

FAMILY: TAENIIDAE
• Genus: Taenia
• Species of Taenia are large cestodes with numerous proglottids.
• The gravid proglottids are longer than broad.
• The rostellummay be present or absent.
• The rostellar hooks are in 2 rows and have a well developed blade, a
handle and a guard.
• Each proglottidhas numerous testes and a lobed ovary.
• The gravid uterus has lateral branches.
• The well developed embryophore is made of minute keratin blocks and
gives the egg its characteristically brown, radiated appearance. Within
these, the oncospheral membrane surrounds the hexacanth embryo or
oncosphere.

Taenia saginata
• It is a tapeworm of man (D.H) and
its cysticercus is found in
cattle(I.H) and other ruminants
• The adult is 5-12 m and rarely up
to 25 m long.
• It comprised of 1000-2000
proglottids.
• The scolex has four suckers
without a rostellum or hooks.
(unarmed tape worm of man)
• The vagina possesses a sphincter
muscle possessed 14-32 lateral
uterine branches.

Life-cycle
• The gravid proglottids are motile and migrate spontaneously or through
anus and spread over the body, clothes, bed or ground, shedding eggs in
the process.
• The hay fields, silos and grazing grounds may be contaminated through
defaecation of infected persons.
• Eggs, when ingested by cattle, are hatched in the intestine and the
released oncospheres are activated under the influence of gastric and
intestinal juices.
• The oncosphere penetrates the intestinal mucosa and reaches various
parts of the body through blood circulation.
• Those reaching the intramuscular connective tissue, and also in fat and
organs, develop into a cysticercus (Cysticercus bovis) and becomes
infective in 10 weeks.
• cysticerci appears to be more in the heart and massetermuscles

• Man becomes infected through eating raw or poorly cooked infected beef
(measly beef- Muscle tissue containing the Cysticercus bovis, the
intermediate stage of Taeniasaginata in cattle)
• Infected person may pass gravid proglottids by approximately 100 days
after the infection.
• Diagnosis: The cysticerci are usually detected during meat inspection or
autopsy.
• Seeing the eggs
• The adult cestode in man is without rostellum and the presence of
sphincter muscle in vagina confirms the diagnosis.

Taenia solium
• It is commonly referred to as ‘pork tapeworm’, found in the small
intestine of man.
• Pig is the main intermediate host for the development of its metacestode
(Cysticercus)
• Rarely man can get the infection by accidental ingestion of infective eggs
of T. solium in cotaminated food / dirty hands and the cysticerci develop
in him leading to serious disease.( neurocysticercosis)
• Autoinfection (Auto- self) also by reverse peristalsis of intestine and the
eggs will hatch to give cysticerci and will penetratethe intestinal mucosa
• So the man can act as D.H and I.H also

• The adult is usually3-5 m or rarely up to 8 m long, having 800-1000
proglottids.
• The scolex is armed with 22-32 rostellarhooks in 2 rows.
• The ovary has 3 lobes. Possessed 7-16 lateral uterine branches.
• Unlike T. saginatathe gravid proglottids, are passed out through the faeces
and do not leave spontaneously.
• The eggs are spherical

Life cycle
• The gravid proglottids are motile and do not migrate spontaneously
through anus
• The hayfields, silos and grazing grounds may be contaminated through
defaecation of infected persons.
• Eggs, when ingested by pig, are hatched in the intestine and the released
oncospheres are activated under the influence of gastric and intestinal juices.
• The oncosphere penetrates the intestinal mucosa and reaches various parts of
the body through blood circulation
• The cysticercus (Cysticercus cellulosae) develops almost in all tissues
(primarily in skeletal and cardiac muscles) of pig.
• It becomes infective after 9-10 weeks.
• Man acquires the infection through raw or poorly cooked infected pork
(measly pork).
• The cestode grows to maturity in about 2-3 months

• Cysticercus in man develops through ingestion of eggs either from
contaminated fingers and food or from auto-infection with eggs by
reverse peristalsis.
• The cysticerci primarily develop in the muscles or subcutaneous tissue,
but may also develop in the brain, spinal cord and eye.
• The cyst which develops in the ventricles of brain may become
(proliferative) in character.
• This type of human infection may be seen in both non-vegetarian
populations.
• The disease caused by development of cysticercus cellulosae is called as
neuro-cysticercosis’ or ‘ocular cysticercosis’ is called ‘depending upon
the location of cysticerci.

• The ‘neuro-cysticercosis’ caused by C. cellulosae is the most serious
manifestation in man, resulting in general malaise, anorexia, severe
headache, nausea, vomiting, dizziness, epilepsy, meningitis,
encephalitisand other abnormal psychiatricmanifestations.
• The lesions are chiefly found in the cerebrum, subarachnoid space, the
ventricles of the brain and occasionally in the cerebellum and spinal
cord. In `ocular cysticercosis', cysticerci develop in the vitreous body;
subretina and unilateralcataract may develop
• Infection in cattle and pig is usually asymptomatic.
• In man, diagnosis of taeniosis is made by the demonstration of
characteristic eggs.
• Specific diagnosis is based on the examination of the scolex, the mature
proglottids, and the number of lateral branches in the uterus of the
gravid segments.

• The infection of cysticercosisin animals is diagnosed during autopsy.
• Immunological methods like counter-immunoelectrophoresis, single
radial immunodiffusion test and ELISA are of great value in the diagnosis.
Recently, western blot assay has been developed for the diagnosis of
porcine cysticercosis.

Control
• It mainly includes public education, sanitation facilities and treatment of
infected persons.
• Education to public through various media about the source and gravity of
infection ,proper cooking of meat, treatment infected persons, hygienic
measures etc.
• Cooking at 65.5 degree or refrigeration of meat at -20 deg. or below for 2
will prevent transmission of infection to man.
• Compulsory inspect of meat and condemnation of infected carcasses will
help to stop the spreadof infection.
• sanitation facilities, supply of clean water and prevention of
contamination of soil water with human faeces helps to a great extent in
controllingthe infection.
• The treatment of animals with compounds like albendazole, mebendazole
and praziquantel is also helpful in elimination of cysticerci in beef and
pork.

Taenia multiceps
• The metacestodeis called Coenurus cerebralis.
• It develops in the brain and spinal cord of sheep, goat.
• After hatching of eggs in the intestine, the young larvae enter the
circulation and localizein the central nervous system.
• On reaching the brain, the metacestodes migrate in the brain tissue and
develop into a fully formed cyst of 5 cm .
• Each cyst contains several hundred protoscolices on the cyst wall.
• After 6 to 8 months of infection, the coenurus becomes infective.
• The definitive host becomes infected by eating the infective cysts.

Pathogenesis:
• The infection is usuallychronic in nature.
• After 4 to 6 months of infection, one or two coenuri may lodge in the
brain.
• The destructionof brain tissue also increases.
• The common clinical manifestation in sheep and goat is referred to as
'gid'.
• The affected animal moves in a circle towards the affected side.
• The animal holds its head against the chest and steps high jerky or
staggering gait
• Paresis of the hind limbs and pressure atrophyof the skull.
• The symptoms are intermittent and the affected animals become
emaciated and cease to feed on progress of the disease.

• Taenia hydatigena: small intestine of dogs and other wild carnivores- D.H
Sheep and other domestic and wild ruminants- I.H. (Cysticercus tenuicollis)
peritoneal cavity to mature
• Taenia ovis: dogs and wild carnivores- D.H
• I.H- sheep and goat. The cysticercus (Cysticercus ovis) which is usually found
in the muscles of heart, diaphragm and masseters.
• Taenia pisiformis: It occurs in the small intestine of dog- D.H
• I. H- are usually the rabbits, hares and rodents. (Cysticercus pisiformis)-
Peritoneal cavity
• Taenia taeniaeformis: It is found in the intestine of cat- D. H
• strobilocercus which develop in the liver of rodents- I.H
• Taenia serialis: It occurs in the intestine of dog and fox-D. H
• Lagomorphs- metacestode (coenurus serialis) develops in the subcutaneous
and intermuscular connective tissues.

Genus: Echinococcus
• Species of the genus are small cestodes with only two to six proglottids.
• Echinococcus granulosus: It occurs in the small intestine of dog and
other canids. –D.H
• It is generally found in almost all Asiaticcountries.
• The length of adult worm varies from 2 to 7 mm and usually possesses 3
to 4 proglottids.
• There are doublerows of rostellarhooks.
• Life Cycle:
• Intermediate hosts are various ungulates and man.
• The metacestodeis called 'hydatid'/hydatidcyst.
• They get infection either through water or forage contaminated with the
faeces of infected dogs.
• Human infection develops through intimate associations with infected
dogs, particularlyin children playing with infected pets/straypups

• On ingestion by the intermediate hosts,
the eggs pass through the intestinal wall,
enter the mesenteric venules and become
lodged in various organs and tissues like
liver, lung, kidney, spleen, heart, brain,
muscles and bone marrow and develop in
to metacestodes stage called hydatid cyst.
• When a dog ingests the cyst the life cycle
is completed.
• Dog will be remain infected for about two
years.
• Hydatid cyst:
• The liver and lungs are the most common
sites where the hydatid cysts develop.
• Cysts are found in liver and lungs of pig,
in livers of cattle and horse, and lungs of
sheep.

• Hydatid cyst: It is composed of a fairly thick outer concentrically
laminated membrane and within this is a granulargerminal membrane.
• From this, a number of brood capsulesdevelop.
• Each brood capsule develops in its inner side `protoscolices'.
• This development takes about five months after infection.
• The brood capsules when detached and float freely in the cyst fluid, is
called `hydatid sand'.
• Occasionally, daughter cysts may also develop within the hydatid cyst and,
on rupture of cysts, external daughter cysts are formed.
• All hydatid cysts do not produce brood capsules, or if produced, they
remain without the protoscolices. These types of cysts are called ‘sterile
cysts'.
• In cattle, hydatid cysts are frequentlysterile.
• Most of the cysts in buffaloes are fertile.
• However, maximum fertility is observed in sheep and that is why sheep is
considered as the most suitable intermediatehost.
• The rupture of the cyst can lead to anaphylactic reaction in man.

Echinococcus multilocularis
• It is found in the northern hemisphere from NorthAmerica to and Russia.
• It is also known as Dwarf tape worm of fox/ Alveolarechinococcosis.
• Adult tapeworms, which primarily occur in foxes
• Life-cycle:It is usuallya sylvatic type involving foxes and rodents-D.H
• Dogs, cats and wolves may also serve as definitive hosts.
• Microtine rodents, especiallywolves serve as intermediate hosts
• Alveolar hydatid cysts (multivesicular infiltrative forms) develop in the
liver on ingestion of the infective eggs.

Pathogenesis
• In heavy infection (echinococcosis), the adult cestodes may cause
enteritis in dogs.
• In intermediate hosts, particularly in man, the pathogenicity due to `cystic
echinococcosis' depends on the severity of infection and the location of
cysts.
• If the cysts are located in the brain and heart, the function of these organs
are frequently disturbed.
• In domestic animals, clinical signs are not usually seen even in heavy
infection.
• The rupture of the cysts through liver capsule into the peritoneum and
diaphragm gives rise to new daughter cysts in the peritoneal and
pleural cavity .

• The leakage of hydatid fluid can lead to various allergic manifestations
like urticaria, asthma and fatal anaphylactic shock and death.
• The growth of alveolar type of hydatid cysts, in case of E. multilocularis,
is peripheral and invasive.
• There are serious complications like formation of malignant tumour and
metastases.

Diagnosis
• It is difficult to differentiate the eggs of Echinococcus in the faeces of dogs
front the species of Taenia.
• For this, a dog must be purged with arecoline hydrobromide (1-2 mg/kg) and
the mucous portion of the purged material is examined for minute adult
cestodes as confirmatory diagnosis.
• Diagnosis of hydatid in animals is usually done during autopsy.
• Radiographic examination is helpful to detect thoracic hydatid cysts in
sheep.
• Immunodiagnostic tests such as complement fixation test (CFT), indirect
haemagglutination (IHA), countercurrent immunoelectrophoresis (CIEP), radio
immunoassay (RIA and enzyme linked immunosorbent assay (ELISA) have
been used with success.
• Besides, radiographic and ultrasound examination are most useful.

Tapeworm Infections in Dogs and
Cats
• Enlist all the tape worms of dog
• Pathogenesis: Adult cestodes are not very harmful to dogs and cats, but
in heavy infection young animals may show non-specific abdominal
symptoms like constipation, diarrhoea, pot-bellied appearance and
unthriftiness.
• The irritation caused by the migrating gravid proglottids of D. caninum,
may cause the dog to drag its anus over the ground.
• Proglottids may also drop off the animals and crawl over the floor, chairs
and clothes.
• Treatment:
• Praziquantel(5 mg/kg) is very effective against all cestodes of dogs

Control
• The best way to achieve this is by controlling the infection of
intermediate hosts and regular treatment of infected definitive
hosts.
• Dogs should be restrained from taking raw offal or meat and from
eating infected small wild animals like rabbit, Tat and mouse.
• Dogs should not be allowed to defaecate in the parks, vegetable
gardens and in the grazing fields used by farm animals.
• For controlling D. caninum, kennels and catteries should be made
free of fleas and lice.
• To prevent the infection of D. latum, raw fish and offal should not
be fed to dogs and cats.

• FAMILY: MESOCESTOIDIDAE
• Mesocestoideslineatus:
• Metacestode:tetrathyridium

CLASS: COTYLODA
•
• The cestodes, instead of having suckers
in the scolex, possess holdfast grooves
(bothria).
• True proglottization and apolysis are
lacking.
• Segmentation is weak or absent and,
when present
• uterus opens ventrally through -a
uterine pore
• Eggs are operculated and pass through
a uterine pore.
• Life-cycle includes a free-living
ciliated larva (Coracidium), a
cercomorphous procercoid in the first
intermediate host, and plerocercoid in a
second intermediate host, and adult
tapeworms in a vertebrate host.
•

FAMILY: DIPHYLLOBOTHRIIDAE
• Segmentation is distinct
• Single or double set of reproductive organs are present in each proglottid.
Testes are numerous.
• Genital pore and uterine pore is present
• Adult tapeworms occur in fishes, birds and mammals.
• Genus: Diphyllobothrium
• Diphyllobothrium latum: It is commonly known as `broad tapeworm' or
`fish tapeworm'
• occurs in the small intestine of fish eating mammals such as man, dog, cat,
pig, in many parts of the world.
• Numerous testes and yolk glands lie in the lateral field.

• Uterus is rosette-shaped with 4 to 8 loopson each side and opens ventrally
in the uterine pore
• Eggs are golden brown, operculated, oval with roundedends,

Life-cycle
• Eggs, which are passed in the faeces of hosts, develop into a ciliated
embryo in water, called 'coracidium'.
• The ciliated coracidium,, while swimming, are ingested by first
intermediate host, crustaceansof the genera Dlaptomusand Cyclops.
• In the haemocoele of the crustaceans, the coracidium, after casting off its
ciliated covering, develops into an elongate solid larva, called 'procercoid'
The procercoid,,bears a six-hooked cercomer.
• On ingestion of the infected crustacean by a second intermediate host
species of fresh water fish which procercoid changes into a wrinkled-
bodied plerocercoidbearing a scolex resembling that of the adult.
• The plerocercoids are found in the viscera and musculature of various
species of fresh water fishes
• Infection to final hosts comes from eating raw or inadequately cooked
infected fish
• The minimum prepatentperiod in dogs is about three weeks.

Pathogenesis
• Infection in man can cause abdominal pain, loss of weight and macrocy
• Anaemia may develop due to competition between the parasite and the host
for vitamin B12.
• D. latum absorbs ten to fifty times vitamin B12 as much as other
tapeworms
• Genus: Spirometra
• These are small to medium-sized cestodes.
• Scolex is spoon-shaped in outline with slit-like broad and shallow bothria.
Uterus is spiraled and never rosettiform in arrangement and opens in
uterine pore.
• Adult tapeworms usually occur in domestic cats and other wild feuds,
occasionallyin dogs and man.
• Spirometra cats in India has been reported from Calcutta, Jabalpur and
Nainital (

Life-cycle
• The unembryonated eggs pass through the faeces of the definitive
hosts.
• these hatch and ciliated coracidia emerge in water.
• The coracidium is ingested by a water Cyclops (Ist I.H) in which it
develops into a procercoid.
• Second intermediate hosts are water snakes, birds, mice and
mammals, including man which ingest the infected Cyclops
containing procercoids which develop into plerocercoid, referred as
‘sparganum'.
• The sparganum is a whitish, elastic, wrinkled plerocercoid
measuring several centimetres in length.
• In man, plerocercoids are found in muscles and subcutaneous
connective tissue
• .The final host (usually cats) ingest the infected second intermediate
host wher plerocercoids develop to become adult tapeworms.

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