4.2.1.

Family Fasciolidae
• large leaf shaped flukes
• Anterior end is usually prolonged into the shape of a cone
– Anterior (oral) sucker is located at end of this cone
• Ventral sucker (acetabulum) is located at level of shoulder
• internal organs are branched, the cuticle is covered in spines
• Important 3 genera
1. Fasciola
2. Fascioloides
3. Fasciolopsis

1
Genus Fasciola

•Called liver flukes

•Cause weight loss, anemia & hypoproteinaemia (by damaging parenchyema of liver,
by distructing liver cell)
•Has 2 species
–Fasciola hepatica--->common in temperate & cooler area of high altitudes
–F. gigantica----->predominates in warm tropical areas
•Final hosts:
–Sheep and cattle are the most important but can infect human and other animals
•Intermediate hosts: snails of the genus Lymnaea:
–For F. hepatica: L. truncatula and L. natalensis
–For F. gigantica: L. natalensis (Africa), L. auricularia
in (Europe and America)

2
 Cont…
Predilection Site
• adults: Bile duct
• immature flukes: Liver parenchyma
• Lungs, under skin, etc. as aberrant flukes in an unusual hosts like human and
horse, etc
F. hepatica
• L. truncatula (amphibious snail) are the main vector(IH) in Europe &
highlands of Africa
• Is prevalent in temperate areas & high altitude regions in tropics & subtropics.
 Cont…

Morphology
Gross
• Adults are flat, leaf shaped & gray-brown in
colour
• cone shaped projection on the anterior end
• Broader anteriorly than posteriorly
– Anterior end distinct & broad shoulders
– Edges converge caudally to form pointed
posterior end

4
Microscopic
• Cuticle is armed with backwardly projecting spines.
• Oral & ventral suckers can be seen
• Egg
– Oval, operculate, golden-yellow with zygote
– twice the size of a strongyle eggs
F. gigantica
• IH _ Lymnea, L. natalensis
– in Africa is a primarily aquatic snail
Morphology
• Up to 7.5 cm hence larger than F. hepatica
• more leafy than F. hepatica
• Has shorter conical end than F. hepatica
• Has no shoulder unlike F. hepatica
• wider posteriorly than F. hepatica 5
 • Associated with animals grazing on naturally or artificially flooded areas or around
permanent water channels of dams.
– Metacercariae are acquired by animals utilizing such areas during the dry
season
• Clinical problems, depending on the rate of infection, occur at the end of that
season or at the beginning of the next wet season. It can infect human

sciola adult Eggs Immature stage

F.hepatica leaf shaped, grey brown in color, measure Oval, yellow,

about 3.5cm long and 1cm wide operculate,
Anterior end is conical and marked off by a 150µm x90µm
distinct shoulder from the body
The young fluke at the time
of entry into the liver is 1-
2mm in length, lancet
shaped
F.gigantica Can reach up to 7.5cm long, the conical Oval, yellow,
anterior end is very short, no distinct Operculate,
shoulders 190µm x100µm

6
Need 6-7 weeks for the egg to develop into metacercaria
Prepatent period is 10-12 weeks for Fasciola hepatica and 13-16
weeks for Fasciola gigantica
Life cycle
– Infection of a snail with one miracidium can produce over 600 metacercariae

– Metacercariae ingested by the final host excyst in the small intestine

– migrate through the gut wall, cross the peritoneum and penetrate the liver
capsule
– young flukes tunnel through the parenchyma for 6-8 weeks

– enter the small bile ducts where they migrate to the larger ducts and
occasionally, the gall bladder
– longevity of F. hepatica in untreated sheep may be years; in cattle it is usually
less than one year.

8
Epidemiology

• Three main factors influencing the production of large numbers of metacercariae to cause outbreaks
of fasciolosis.
1. Availability of suitable snail habitats:
– wet mud to free water
– permanent habitats
• banks of ditches or streams , edges of small ponds are preferable
2. Temperature:
– a mean day/night temperature of 10oc or above is necessary both for snails to breed and for the
development of Fasciola with in the snail
– all activity ceases at 5o C this is also the minimum range for the development and hatching of
Fasciola eggs.

9
3. Moisture
• ideal moisture conditions
– snail breeding and the development of Fasciola within snails
• during rainfall exceeds transpiration and field saturation is
attained F. hepatica
• Pathogenesis
 Pathology of Fasciolosis depends on;
1. Phase of parasitic development in the liver:
 initial phase occurs during migration of immature fluke in liver
parenchyma resulting in liver damage and hemorrhage
 second phase occurs when adult fluke is the bile duct and result
from hematophagic activity and damage to liver mucosa by
cuticular spine
• 2. Animal host affected: disturbed metabolism, emaciation and
production loss
10
Severity depends on

Number of metacercariae ingested

The phase of development in the liver
The species of host involved
During the first phase, immature, wandering flukes destroy liver tissue and
cause hemorrhage.
The second phase occurs when the flukes enter the bile ducts, where they
ingest blood and damage the mucosa with their cuticular spines.

Ovine fasciolosis
 Three forms of disease
Ovine fasciolosis Acute

Sub acute

Chronic
Clinical sings
a. Ovine Fasciolosis
1. Acute (2-6 weeks after infection)
– complicated by concurrent infections
– “Cl. novyi” resulting in “Black disease”.
• weakness, pale mucus membranes, dysponea
• palpable enlarged livers with abdominal pain & ascites

2. Subacute
• where metacercariae are ingested over a longer period
• rapid loss of condition, marked pallor of mucus membranes
• enlarged & palpable liver, submandbular or facial edema & ascites
12
3. chronic disease

– Seen mainly in late winter/ early spring

– Is the most common form of the disease.

– It occurs 4-5 months after the ingestion of moderate numbers, 200 -

500, of metacercariae

The principal pathogenic effects are

– Anemia and hypoalbuminaemia and more than 0.5 ml blood per fluke
can be lost into the bile ducts each day.

– progressive loss of condition, anaemia and hypoalbuminaemia

– emaciation, pallor of mucous membranes, submandibular edema &

ascites
13
• Chronic cholangitis( replecements of connective tissue and calcification of
liver due to the immature flucks,
• Common due to F. gigantica (reading ass.
Bovine Fasciolosis

• Acute and sub acute fasciolosis may occurs occasionally

• chronic form of the disease is the most important seen mainly in the late winter/
early spring.

• The pathogenesis is similar to that in sheep

– calcification of the bile ducts and enlargement of the gallbladder

• Diarrhea is not a feature of bovine fasciolosis unless it is complicated by

presence of Ostertagia species.
14
Diagnosis
• Clinical signs
• Seasonal occurrence
• Prevailing weather pattern
• Previous history of fasciolosis or the identification of
snail habitats
• examination of faeces for fluke eggs
• Determination of plasma levels
– glutamate dehydrogenase(GLDH) due to
parenchymal damage
– gamma glutamyl transpeptidase(GLD)due to damage
to epithelial cells lining bile duct

15
Treatment
• Only one drug, Triclabendazole, which will remove the early parenchyma stages.

• Rafoxanide and nitroxynil and others including albendazole is effective at an

increased dosage rate.

Control

• It should be approached in two ways;

– Reducing populations of the intermediate host, Snail
– Using anthelmintics
• Reduction of snail populations
• Drainage → ensure permanent destruction of snail habitats
• Fence off limited areas of snail habitat or treat annually with a molluscide
(copper sulfate)
• The application of a molluscicide should be combined with anthelmintic
treatment 16
Use of anthelmintics
• Prophylactic use of fluke anthelmintics
– Reducing pasture contamination by fluke eggs at a time most
suitable for their development i.e. April to August
• Removing fluke populations
– A time of heavy burdens, at a period of nutritional deficency
– During pregnancy stress
• Prophylactic treatment in cattle is directed at reducing the fluke
burdens in winter.
Control of F. gigantica
– The principles are the same as for the control of F. hepatica
– IH is water snail and its control is depends on a different
approach from that of mud snail L. trunculata
– When watering stock is from a reservoir or stream
• fencing the water source and leading a pipe to troughs.
– Water troughs be cleaned out regularly
– Molluscicides are usually impractical because of the large body
of water involved 17
 Family: Schistosomatidae
General feature
• Live in the blood vessels (=blood flukes) of the alimentary tract and the urinary
bladder
–Responsible for severe and debilitating disease known as Schistosomosis or
bilharziosis in animals and man
• Schistosomes are not hermaphroditic but dioecious, forming separate sexes
• Adult worms have elongate tubular bodies, each male having a unique
gynecophoral canal in which a female worm resides ( female worm permanently
attached)
• They have digenetic life-cycles involving aquatic snails as intermediate hosts
• Eggs deposited in the circulation penetrate the gut or bladder to be excreted with faeces or
urine
• The most important genus is SCHISTOSOMA
Genus Schistosoma
• Host: mainly human , sheep and cattle
• Intermediate hosts: water snails
• Distribution: tropics and subtropics
 Morphology

• Adult

a le
M
a le
– Adult flukes are elongate tubular worms (10-20mm

m
Fe
long), with rudimentary oral and ventral suckers.
– Males are shorter and stouter than females, and they
have a longitudinal cleft (gynecophoral canal or
schist) in which the longer slender female lies folded

gynecophoral canal

Dr. Atinafu R.
 Eggs
• Eggs are round to oval in shape, operculate (hinged at one end) and contain a
developing embryonic larva(oviviviparous (miracidium)
• Differences in egg morphology can be used to distinguish
between Schistosoma species
• Mansoni group
– S. mansoni producing oval eggs with a sharp lateral spine
• Japonicum group

– S. japonicum (not found in tropics, found in asia due to IH : forming round eggs
with a rudimentary lateral spine
• Haematobium group  
– S. haematobium , S. mattheei, S. bovis , S. intercalatum etc: producing
Oval/Spindle shaped eggs with a sharp terminal spine

S. bovis
 SCHISTOSOMA
Parasite species Definitive host Site of infection Egg Snail vector Geographic
excretion location

veins of
S.haematobium humans, primates urogenital urine Bulinus Africa
system

S. mansoni humans, rodents faeces Biomphalaria Africa, America

S. japonicum humans, ruminants, faeces Oncomelania SE Asia

carnivores

S. intercalatum humans, rodents, cattle intestinal mesenteric veins faeces Bulinus, Africa
Physopsis

Africa, SE Asia,
S. bovis ruminants faeces Bulinus Middle East,
Europe

S. mattheei Ruminants/human faeces Bulinus Africa, Middle

East
 Cont…
• Miracidia
– are elliptical free-swimming larval stages (~200µm Miracidia
long) covered with cilia.
• Sporocysts
– Pleomorphic sac-like bodies which contain
developing cercariae
• Mature cercariae
– are elongate free-swimming larval stages (400-
600µm long) consisting of a tapering head (with
prominent penetration glands) and a forked tail  

Dr. Atinafu R.
 Lifecycle

• The female in the mesenteric vein inserts her tail into a small venule and
since the genital pore is terminal, eggs are deposited there
• Eggs aided by their spines and proteolytic enzymes (manipulate immune
system) secreted by the unhatched miracidia, penetrate the endothelium
to enter the intestinal or urinary bladder submucosa and then the lumen
of the intestine or U. bladder
• Eggs passed out in feces or urine
• Eggs hatch in water and we get miracidia
• Miracidium penetrate appropriate snail intermediate host and develop
into numerous cercariae Dr. Atinafu R.
 Cont…

•Cercariae penetrate out of snail body and

swim in water
• Cercariae infect host through skin
penetration or ingestion
• Cercariae lose their forked tail to transform
into schistosomulae
• Schistosomula travel via blood stream to the
systemic circulation
• In the liver they sexually mature before
migrating to their final site (veins)
Dr. Atinafu R.
 Epidemiology
 Epidemiology: very similar to that of Fasciola spp., and
Paramphistomum spp.,
 Schistosoma spp. being totally dependent upon water as a
medium for infection of both the intermediate and final host.
 Small streams, irrigation canals, marshy or damp areas are the
main snail habitats.
 Eggs, miracidia and cercariae are short-lived with seasonal
transmission directly related to rainfall and temperature.
 The fact that percutanous infection may occur and encourages
infection where livestock are obliged to wade in water.
 Pathogenesis
• S. bovis 
– Schistosomiasis is unusual amongst helminth diseases for two reasons:
• Much of the pathogenesis is due to the eggs only parasite which its eggs are
pathogenic (rather than larvae or adults); and
• Most of the pathology is caused by host immune responses
– The course of infection is often divided into 2 major phases: acute and chronic
• The acute phase is coincident with first egg release and is characterized by allergic
responses, gastrointestinal discomfort such as diarrhea and eosinophilia
• The chronic phase occurs in response to the cumulative deposition of fluke eggs in
tissues and the host reactions that develop against them.
– Not all the eggs laid by female worms successfully penetrate the gut or bladder walls,
many are swept away in the circulation and become trapped in organs where they
elicit strong granulomatous responses
 Clinical signs

– The disease is much more important in sheep than in cattle

– Cattle rarely show clinical signs
– Acute phase:
• diarrhea and anorexia 7-8 weeks after heavy infection
– Chronic phase:
• Anemia, hypoalbuminemia due to hemorrhage , emaciation
and loss of weight and production

Dr. Atinafu R.
• Diagnosis

– Clinico-pathological picture of diarrhea, wasting and anemia

– History of access to natural water sources where the disease is
known to be prevalent
– Demostration of characteristic eggs in feces (ex. S. bovis) or urine
(ex. S. hematobium)
• Treatment
– The drug of choice for the treatment of all Schistosoma spp. is
praziquantel
– While timely treatment is effective, cured individuals rapidly
become re-infected in endemic areas
Control
– Various control programmes have therefore been developed based on mass
chemotherapy in conjunction with preventive measures, including improved
sanitation, snail vector control, modifying habitats and farming practices, and public
education campaigns
– Water contamination can be reduced by preventing the ingress of parasite eggs as well
as curtailing the asexual amplification cycle in snail hosts
– Snail populations may be reduced by the strategic use of molluscicides (niclosamide
or copper sulphate), draining marshes and swamps, and clearing channels of
vegetation
Dr. Atinafu R.
In Human

• Schistosomosis in human called by old name Bilharzias

Species
– S. mansoni
– S. japonicum – occasionally occur in domestic livestock
– S. haematobium – in the veins of the bladder
• Cutaneous larva migrans (cause degeneration of skin, often called
‘swimmers itch’ occurs in human caused by cercaria of animal
schistosomes

Dr. Atinafu R.
Principle of control of trematode

 Effective control of most trematode infection on strategically applied

chemotherapy

 Improvement in current farm management can reduce chance of infection by

limiting the contact between intermediate and final host

 Direct action may be taken to reduce or eliminate intermediate host

population

 Animal husbandry system such as zero-grazing (cut and carry) and tethering
of animals may minimize the risk of trematode disease

Dr. Atinafu R.
Control strategies for F. hepatic and F. gigantica

 Effective control requires well planned and integrated control program

designed for each farm, area, country or region

 Strategic application of anthelmintics, eliminating the parasite from

the host at most appropriate time for effective prevention of pasture
contamination

 Reduction in number of intermediate host snail by chemical or

biological control or management practice such as draining, fencing
and other

 Reduction in risk of infection by planned grazing management

Dr. Atinafu R.
Strategic chemotherapy of ruminants

 Basic principles of Strategic anthelmintic application (treatment/prophylaxis)

are;

 Prophylactic treatment of ruminants toward the end of period of

ecologically reduced activity of the parasite and intermediate host
(during dry or extreme cold)

 Curative treatment about 1-2 months after expected infection of the

hosts

 Additional treatment in highly contaminated area where seasonal

variation do not significantly affect the life cycle of the flukes

Dr. Atinafu R.
Strategic chemotherapy of ruminants

 the economics of chemotherapy should be evaluated for each farm, area

and country including;
 Assessment of anthelmintic availability
 Price and economics of livestock production system
 More treatment are necessary if the drug are only effective against
mature flukes
 Price of drug (effective against immature and mature) is
considerably higher than those effective against mature
 If animals grazing communal pasture areas, it is important to achieve a
synchronized reduction in pasture contamination of egg if possible
 Ideally all animals in the area should receive treatment within a short period
of time

Dr. Atinafu R.
Chemical control of snails

 Use of molluscicides for control of snail intermediate host is potential tool

for control of fluke infection

 Before considering chemical control of snail it should be noted

 Many habitats are topographical unsuitable for use of

molluscicides

 They are toxic to environment

 Regular (yearly) application is require because of rapid repopulation of
snail may occur
 They are not species specific and may destroy edible snails highly valued
as food in some communities
 They are expensive

Dr. Atinafu R.
Biological methods of snail control

 Report from different part of the world indicates that number of plants have
molluscicidal properties (endode)

 Planting of these tress and shrubs along stream and irrigation channels can
reduce the number of snail

 Introduction of large number of duck into rice field after harvest has been used
to reduce snail population (duck eat snail)

 Introduction of edible snail species unsuitable as intermediate host into the

habitat of the host snail may prevent flukes from completing their life cycle

Dr. Atinafu R.
Managemental methods of snail control

 To prevent snail habitats from developing by regular clearing drainage

channel in vegetation

 To keep livestock away for pasture contamination with metacercariae. This

may only possible when number of animals involved is small

 Establishing proper watering facilities to prevent animals from drinking from

lakes, ponds and streams

Dr. Atinafu R.
Classification of parasites

kingdom

Animalia Protista
(single celled)
Phylum Platyheliments Nematoheliments Arthropoda Protozoa
Class

Trematoda (Nematoda)

Cestoda
.
• Classification
 Order Cotyloda or pseudocestode
contain family of veterinary importance
are (Diphyllobothridae)
 Genus Diphyllobothridium and
Spirometra associated with aquatic
food chain
 Order Eucestoda or true tapeworms
 associated with terrestrial food chain
Cestode/tapeworms
 They are multicellular, eukaryotic and motile
organisms.
 The body is segmented, each segment contain one
and sometimes two sets of male and female
reproductive organs
 have a flat, tape-like body and consist of
segments called proglottids
 The body is filled with a parenchyma and do not
have a body cavity (acoelomate).
 Adult tapeworms are entirely endoparasitic
worms that inhabit the intestinal lumen of their
hosts.
 Larval forms called metacestodes, which are
cystic or solid, inhabit extraintestinal tissues of
their intermediate hosts particularly in muscles,
visceral organs and sometimes the brain.
 Tapeworms vary in length from 2 to 3 mm to 10
• Tapeworms are hermaphroditic and each
proglottid contains both male and female organs.
• Life cycle involves larval development in 1 or 2
intermediate hosts (indirect L/C)
• Animals/humans may serve as definite host, as
intermediate host, or as both, depending on the
species of tapeworm.
• All tapeworms are obligate parasites, i.e., they
cannot complete development(their life cycle)
without parasitizing their hosts.
Morphology of Tapeworms
 The tapeworms have long, flat
bodies that are divided into three
sections: 
Scolex, Adult
Neck (usually short)
Strobilla/Proglottid
(segments). 

Proglottid
• The scolex contains suckers and may have hooks
used for attaching to the host's tissues.
• Anteriorly the scolex may be armed with a
protrusible part, the rostellum, which may bear
one or more rows of hooks.
• Proglottids are continuously formed from the neck
region in a process called strobilization
• As new proglottids are formed, the older
proglottids move posteriorly.
• The segments nearest the neck are immature (sex
organs not fully developed) and those more
posterior are mature
• Each mature proglottid contains a complete set of
male and female reproductive organs that
produce sex cells. 
• The proglottids of tapeworms increase in size
from head to tail
• All the proglottids together form the strobila.
• The strobila differs in number and shape in
various tapeworm species.
• Tapeworms have neither a digestive system,
nor circulatory or respiratory systems.
• They have excretory cells known as flame cells
(protonephridia) and a simple nervous system.
• Cuticle - The outer cover of Cestode parasites/

protective skin and is important in

absorption of nutrients
• This covering also protects the worms from the host's
immune reactions and digestive acids/ juices
• Each organs of reproduction occurs in each proglottide
(each segment of Strobila) and they are Monocious
(both sex in one segment/parasite)
• The reproductive organs in each proglottid have a
common opening called the genital pore.
• The genital pores (used only for copulation) usually
open on the lateral margin/margins of each segment;
• Uterus has no opening to the outside of the body in
each segment.
• The cestodes vary in size from a few millimeters to
several meters in length.
Development of proglottids
 New proglottids (immature) bud from behind the
scolex/neck
 As they are pushed back, they mature (eggs are
produced)
 When filled with eggs, they are “gravid”
proglottids.
 Hexacanth embryos (onchospheres) develop
within the eggs.
• Gravid proglottids often detach from the strobila
and disintegrate during passage through the
digestive tract releasing eggs or are released intact
in the feces.
Full developed egg has
1. Onchosphere (hexacanth or 6-hooked embryo)
2. Embryophore thick, dark, radially striated shell
and it surrounds the onchospheres
3. Capsule is outer most cover, true shell which is
delicate membrane and often lost while still in
uterus
 Transmission
 Depends on the species of the parasite
»Ingestion of eggs
»Ingestion of intermediate host
»Invertebrate-accidental

50
 Diagnosis of cestode parasites
• Eggs of some tapeworms can be speciated, but not the Taenia
spp. Anal swabs are often helpful due to squeezing of segments
on the outside of the stool as it passes through the anus and
fecal flotation method
• Proglottids (degree of branching, Shape, Size) and The scolex
(Shape, Hook, Rostellum) are very important for species
differentiation
• The type of species of host affected and habit of feeding also
important in diagnosis
• Beyond those, clinical and laboratory diagnostic methods such
as cyst viability test, radiology and serological tests
(eosinophilia, antibody
3.2. 1. Family Taeniidae
• Adults are found in domestic carnivores & omnivores
(Human and pig)
– Scolex has 4 suckers
– All are armed except T. saginata
– Rostellum is armed with a double circlet of hookes
– Has single set of genital organs
– Gravid segments are longer than are wide
• Metacestod………..Cysticercus, coenurus or hydatid cyst
occur only in mammals.
1. Genus Taenia
– the most important genus
– Has zoonotic importance
– Larval stages called C. bovis are found in muscles of cattle
52
1.1.Taenia saginata (Bovine tapeworm)
– cosmopolitan distribution in beef eating countries

– Metacestode (Cysticercus bovis)- -----muscle of cattle

– Adult ----small intestine of human
– Economic and public health importance
Morphology
– the adult & larva are unarmed
» i.e. has neither rostellum nor hooks
– Uterus of gravid segments
» T. saginata has 15-30 lateral branches
» T. solium has 7-12 lateral branches
– C. bovis predilection sites are in the striated muscles
» heart, tongue, masseter, shoulder &
53
intercostal muscles
 Identification
Adult found in man only measure 5-15m
Scolex exceptional among the species of Taenia has neither
rostellum nor hooks
Uterus of gravid segment has 15-30 lateral branches
compared to T. solium (7-12)
In bovines (IH) the mature cysticercus bovis is greyish
white, about 1cm in diameter and filled with fluid in which
scolex is usually clearly visible which lack rostellum and
hooks
Life cycle
• An infected human may pass millions of eggs daily,
mainly as intact segments each containing about 250,000
eggs
– can survive on pasture for several months.
• During the eggs ingestion by bovine the onchosphere
travels via the blood to striated muscle, then it is enclosed
by the host in a thin fibrous capsule
• It grossly visible about two wks later as a pale,
semitransparent spot
• Human becomes infected by ingesting raw or inadequately
cooked meat, containg the metacystod
• Development to patency takes 2-3 months.
55
Pathogenesis and clinical signs
• Cysticerci in the muscle of cattle is not associated with
clinical signs
– Massive infections of T. saginata eggs have developed
sever myocarditis and heart failer
• In human the adult tapeworm may produce diarrhea and
hunger pains
– infection is usually asymptomatic and is mainly
objectionable on aesthetic grounds
– Incidence in human of developing countries >20% while
<1% in developed
Epidemiology
• Contaminated hands of stockman causing early infection of
calves-poor sanitation
• Use of human sewage as a fertilizer
• Dispersal of T. saginata eggs by birds 56
Diagnosis
• Proper inspection of carcass

– the masseter, tongue, heart, intercostals muscles,

diaphragm, and triceps muscles
Treatment and control
Praziquantel is effective experimentally
 high standard of human sanitation, cook meat (>570C),
regular meat inspection
Froze infected muscle at 100C for 10 days
• If more than 25 C. bovis destroy the carcass
– Avoid use of human sludge as fertilizer
– Education of society (good personal hygiene and toilet
usage) 57
1.2. Taenia solium (Pork tapeworm)
• Adults------ Human , are armed

• Cysticercus cellulosae -----muscles of pig

• Cysticerci may also develop in human, human
cysticercosis, is the most serious aspect of this zoonosis.
Distribution
• Latin America, India, Africa and part of the far East, apart
from religious sanctions on the eating of pork.
Identification
• Similar to T. saginata except
– scolex having a rostellum armed with two concentric
rows of hooks
– uterus of the gravid segment has fewer lateral branches58
Life cycle
• Similar to that of T. saginata
• man (final host) may also become infected with cysticerci
– accidental ingestion of T. solium eggs
– Autoinfection, in a person with an adult tapeworm, by reverse
peristalsis,
Pathogenesis and clinical signs
• Similar to that of T. saginata,
• man is infected with cysticerci, various clinical signs may occur
• in the CNS, cysticercosis
– Mental disturbances
– Epilepsy
– Increased intra cranial pressure
• Loss of vision (ocular lesions)

59
Epidemiology
• Similar to that T. saginata except that it depends primarily
on the close association of rural pigs with human and their
unrestricted access to human faeces.
Diagnosis
– Similar to that of T. saginata
– In human cerebral cysticercosis
– CAT (computerized axial tomography) scanning
techniques
– antibody to cysticerci in the cerebrospinal fluid.
Treatment
• No effective drugs to kill cysticerci
• Praziquantel and albendazole are of some value
Control
• Enforcement of meat inspection regulation and deep
freezing procedures.
• Exclusion of pigs from contact with human faeces.
• Thorough cooking of pork
• Proper standard of personal hygiene
60
 Genus Taenia in dog & cats
Taenia multiceps
• The adult tapeworm is up to l00cm long and is found in the dog
and wild canids
• The onchospheres, when ingested by sheep or other
ruminants/man are carried in the blood to the brain or spinal
cord where each develops into the larval stage, Coenurus
cerebralis
• This is readily recognized as a large fluid-filled cyst up to 5.0cm or
more in diameter which bears clusters of scolices on its internal
wall
• The Coenurus takes about eight months to mature in the central
nervous system and, as it develops, clinical signs commonly occur.
– These depend on the location of the cyst or cysts and include
Signs vary based on location of larvae
• Brain (cephalic form):- circling (gid & stager), and visual
defect
• Spinal cord (modularly form):- paraplasia (paralysis below
the waist)
Diagnosis
• Based on History and clinical sign
• Confirmatory diagnosis is only done by PM
examination
Treatment
• No treatment in IH, but praziquantel have some effect
• FH – use of mebendazole.
• Surgical removal of cyst is also possible after proper
locating of the cyst by x-ray.
Control
• Regular treatment of dogs with taenicidal drugs
• Educate animal owners and butchers not to give head
62
 Genus Echinococcus
• The smallest Cestodes of domestic animals.
Two species E. granulosus and E. multilocularis
E. granulosus
Have two major strains E.g. granulosus and E. g. equinus
Strains Final host Intermediate Adult site Larval site
host
E.g. granulosus Dog and wild Domestic Small Liver and lung
canines ruminants, intestine
man, pig, wild
ruminants:
horse and
donkey are
resistant

E.g. equinus Dog and red Horse and Small Liver and lung
fox donkey intestine
63
Morphology Cont…
Gross

– About 6mm long

– Has scolex and 3-4 segments, the
terminal or gravid segment
occupying about half the length
of the parasite
– The scolex is typically taeniid,
and each segment has a single
genital opening.
– Thc embryophore is similar to
that of Taenia spp., radially
striated and containing a six-
hooked onchosphere 64
Lifecycle
•The prepatent period in the final host is around 40-50
days, after which only one gravid segment is shed by
the tapeworm per week
•The onchospheres , being viable for about two years in
the external Enviroment
•After ingestion by the intermediate host, the
onchosphere penetrates the gut wall and travels in the
blood to the liver, or in the lymph to the lungs
•Growth of the hydatid is slow, maturity being reached
in 6-12 months.
•In the liver and lungs the cyst may have a diameter of
up to 20cm
• The Cyst capsule consists of an outer membrane and an
inner germinal epithelium from which, when cyst growth
is almost complete, brood capsules each containing a
number of scolices are budded off
• Many of these brood capsules become detached and exist
free in the hydatid fluid; collectively forming the
'hydatid sand‘
• In sheep about 70% of hydatids occur in the lungs, about
25% in the liver, and the remainder in other organs.
• In horses and cattle more than 90% of cysts are usually
found in the liver
66
Pathogenesis and clinical signs
• The adult is not pathogenic
• The hydatid in the liver and lung is with out clinical sings
• In the kidney, pancreas, CNS or marrow cavity of long bones, cause a
variety of clinical signs.
• In man the pathogenicity is significant.
• lungs respiratory symptoms
• If several hydatids in the liver gross abdominal distension.
• If a cyst rupture death from anaphylaxis
– daughter cysts may develop in other regions of the body.
67
Epidemiology
• The dog -------ruminant offal containing hydatid cysts.
– Sheep the most (natural host)
– camels in the middle Eat and in northern Europe and
Russia Reindeer.
• Hydatidosis in human
– coats of dogs
– vegetables and other food stuffs contaminated by dog
faeces.
Diagnosis
• Clinicaly rarely in domestic animals
• In man
– scanning techniques to locate the cysts.
• The adult in dog is small 68
Treatment
• Praziquantel and confine dogs for 48 hours
• In man …… surgically
– Menbendazole
– Albendazole
– Praziquantel therapies have been reported to be
effective
Control
• Regular treatment of dogs
• Denying dogs access to abattoirs
• Proper disposal of sheep caresses, containing
69
hydatids.
2.2. Echinococcus multilocularis
Final Hosts: wild canids domestic dog and cat
IH
• Microtine rodents : voles and lemmings and insectivores, larger mammals
including man are also susceptible.
Site
• Adult occurs in the intestine , Hydatids mainly in the liver.
Morphology
• Has scolex and 4-5 segments
Distilibution
• Northern hemisphere
Lifecycle
• The intermediate host is infected by ingestion of the onchosphere, and the
larval stage develops primarily in the liver as the so-called multilocular or
alveolar cyst, a diffuse growth with many compartments containing a 70
• Diagnosis
– Diagnosis depends on the demonstration of
segments or individual taeniid eggs in the faces
– We can use a purgative substance such as arecoline
to expel the adult worm from the body for
examination
• Treatment
– For adult tapeworms a number of effective drugs are
available including praziquantel, mebendazole etc
• Control
– Feed dogs and cats only cooked meat
– Properly dispose infected offal
– Treat infected dogs 71