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CestodesTapeworms
- 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.
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
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.
E. granulosus is found in: Australia, Argentina, Chile, Africa, eastern Europe, the Middle East, New Zealand, and the Mediterranean region, particularly Lebanon and Greece.
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
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)
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 iscompleted whena dog ingestslamb
containingcysts
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.
New
larvae,
called
scolices,
develop in large
numbers within
the brood
capsule.
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.
The liver
and
The lungs
are
the
Most common
sites.
55
25
632,5
0
10
20
30
40
50
60
1st Qtr
ЧЕРНОДРОБНАБЕЛОДРОБНА МОЗЪЧНАСЛЕЗКОВАБЪБРЕЧНА
Cysts may involve any Organ: - bone
- medullary cavity
- the CNS
- the heart
- spleen
Prognosis
Complications:• Mechanical icterus• Cholangitis• Absces• Peritonitis• Empiema• Rupture• Anafilactic chock• Dissemination• Secondary multiplic ech
Recidives (> 30 %)
Letalites 1 до 15 %.
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).
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.
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.
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.
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.
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.
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.