1. Cestodes
Tapeworms
- are segmented worms
- The adults reside in the gastrointestinal tract, but the larvae can be
found in almost any organ
- Human tapeworm infections can be divided into two major clinical
groups:
In one group, humans are the definitive hosts, the adult tapeworms live
in the gastrointestinal tract (Taenia saginata, Diphyllobothrium,
Hymenolepis, and Dipylidium caninum).
In the other, humans are intermediate hosts, and larval-stage parasites
are present in the tissues.

2. Echinococcosis
Hydatid desease
Echinococcosis of humans is caused by the
larval stage of Echinococcus granulosus
- ECHINOCOCCUS GRANULOSUS GRANULOSUS
- ECHINOCOCCUS GRANULOSUS BOREALIS
- ECHINOCOCCUS GRANULOSUS CANADIENSIS
- ECHINOCOCCUS GRANULOSUS EQUINUS
E. granulosus produces unilocular cystic lesions

3. E. granulosus is
prevalent in areas
where livestock is
raised in association
with dogs.
E. granulosus
is found in:
Australia, Argentina,
Chile, Africa, eastern
Europe, the Middle
East, New
Zealand, and the
Mediterranean
region, particularly
Lebanon and Greece.

4. E. granulosus
is found in:
Australia, Argent
ina, Chile, Africa
, eastern
Europe, the
Middle
East, New
Zealand, and the
Mediterranean
region, particular
ly
Lebanon and
Greece.

5. Echinococcal species have 2 hosts:
• intermediate and
• definitive hosts
1. Definitive hosts are dogs,
that pass eggs in their feces
2. Intermediate hosts are:
• sheep, cattle, humans, goats,
camels, and horses

6. Etiology
Adult E. granulosus is a
small (2,7-5 mm long)
cestode,
which lives for 5 to 20 months
in the jejunum of
dogs, чакал, вълк,
He has scolex with hookless,
only 3-4 proglottids –
immature, mature, and gravid
(400 — 800 eggs)

7. After humans
ingest the eggs,
embryos escape
from the eggs,
penetrate the
intestinal
mucosa, enter
the portal
circulation,
and are carried
to organs.
The life cycle is
completed when
a dog ingests
lamb containing
cysts

8. Larvae develop into
fluid-filled unilocular
hydatid cysts that
consist of an external
membrane and an inner
germinal layer.
Daughter cysts
develop from the inner
aspect of the germinal
layer, as do germinating
cystic structures called
Brood capsules.

9. New
larvae,
called
scolices,
develop in large
numbers within
the brood
capsule.

10. Clinical Manifestations
1. Slowly enlarging EC generally remain asymptomatic, until
their expanding size or their space-ccupying effect in an
involved organ elicits symptoms.
Since a period of 5 - 20 years EC may be discovered incidentally
on a routine x-ray or US study.
2. Rupture can occur: spontaneously or at surgery .
Cysts may involve any organ.

11. The liver
and
The lungs
60
are 55
the 50
Most common
40 ЧЕРНОДРОБНА
sites. БЕЛОДРОБНА
30
25 МОЗЪЧНА
20 СЛЕЗКОВА
БЪБРЕЧНА
10
6
32,5
0
1st Qtr

12. Cysts may
involve any
Organ:
- bone
- medullary cavity
- the CNS
- the heart
- spleen

13. Prognosis
Complications:
• Mechanical icterus
• Cholangitis
• Absces
• Peritonitis
• Empiema
• Rupture
• Anafilactic chock
• Dissemination
• Secondary multiplic ech
Recidives (> 30 %)
Letalites 1 до 15 %.

14. Diagnosis
Radiographic and related imaging
studies are important in detecting
and evaluating echinococcal cysts.
X-ray will define pulmonary cysts:
- usually as rounded, uniform
density
- but may miss other cysts in other
organs unless there is cyst wall
calcification (as occurs in the liver).

15. Pathognomonic
finding is:
-daughter cyst
within the larger
cyst.
-eggshell or mural
calcification
Thise findings on
CT,
is indicative of E.G.
invasion and helps to
distinguish from
carcinomas, bacterial
or amebic liver
abscesses, or
hemangiomas.

16. A specific diagnosis can be made
by:
the examination of aspirated
fluids for scoliceal hooklets, but
diagnostic aspiration is not
conventionally recommended
because of the risk of fluid leakage
resulting in either dissemination or
anaphylactic reactions.

17. Serodiagnostic assays
Serodiagnostic methods are:
• HAT, positive titres 1: 200
• ELISA, positive titres 1: 200
• IFA positive titres 1: 20
• immunoblotting test
Serodiagnostic assays can be a negative
(up to 30 % of patients may have negative
resultes), but does not exclude the diagnosis
of echinococcosis.

18. TREATMENT
Therapy for echinococcosis is based on considerations of
the size, location, and manifestations of cysts and the
overall health of the patient.
• Surgery, when feasible, is the principal definitive method of
treatment; E. granulosus cysts are excised.
• Risks at surgery from leakage of fluid include anaphylaxis
and dissemination of infectious scolices. The latter
complication has been minimized by the instillation of
scolicidal solutions such as hypertonic saline or
ethanol, which may cause hypernatremia, intoxication, or
sclerosing cholangitis.

19. Chemotherapy
• As medical therapy, albendazole, given at a
dose of:
• 10-15 mg/kg/day for 30 days, with 15 days
intervals or
• 400 mg twice a day for 12 weeks,
is most efficacious, although multiple courses
may be necessary
• Response to treatment is best assessed by
repeated evaluation of cysts by CT or
MRI, with particular attention to cyst size and
consistency.

20. Prevention
In endemic areas, echinococcosis can be prevented by:
- administering praziquantel to infected dogs
every 3 months
- by denying dogs access to butchering sites and
to the offal of infected animals.
- Limitation of the number of stray dogs is helpful
in reducing the prevalence of infection among
humans.