Hydatid Disease . Dr. Firas Obeidat , MD. Species. Echinococcus granulosis. E. Multilocularis (more malignant). E.vogeli . E.oligarthus . Life - cycle. The major "intermediate host" is a herbivore, mainly the sheep (in other cases is the pig, horse, camel etc).
Dr. FirasObeidat, MD
E. Multilocularis (more malignant).
The major "intermediate host" is a herbivore, mainly the sheep (in other cases is the pig, horse, camel etc).
The major "definitive host", a carnivore mainly the dog ( in other cases is fox, wolves etc).
Infection of the intermediate host occurs after ingestion of food contaminated with eggs containing embryos (oncospheres) passed from the faeces of the "definitive host" .
Endemic areas are Mediterranean countries, Middle East, Turkey, Africa, South America, Asia, Australia and New Zealand.
Uncommon in the USA and most of central Europe.
The eggs (oncospheres) penetrate the wall of the intestine of the intermediate host and via the blood stream they first reach the liver.
The liver is affected in (60%), and the lungs in (30%).
The right lobe is affected in (80%) and in 1/3 of the cases the cysts are multiple.
Single organ involvement in 90% of cases.
The outer adventitial layer coming from the host is called ectocystorpericyst.
The two inner layers coming from parasite, the most inner germinal layer and the outer laminated layer together form the endocyst.
The germinal layer secretes the laminated layer which is mucopolysaccharide - protein-lipid complex.
The cavity of the cyst contains the hydatid fluid which is clear and similar to interstitial fluid.
The time required to become mature varies from 10 to 20 months.
Daughter cysts (degenerated or secondary cyst), which has fragments of germinal layer. It may develop within the primary cyst or separately.
Calcification of the cyst occurs usuylly after 5-10 yrs, commonly in liver cyst . Complete calcification indicate nonviable cyst.
Usually protoscolices produced after one year following the infection.
Most of the cysts remain uncomplicated (82%).
The most common symptom in these cases is right upper quadrant pain, liver enlargement or palpable mass ( 1-5 cm/yr increase in size).
Symptoms occur as a result of mechanical effect or generalized toxic reaction due to the presence of parasite itself.
Symptoms usually when size is > 10 cm.
Suppuration ( 2 bacterial infection)
Liver is the primary site of infection then spreads by direct extension or hematogenous dissemination.
It behave like malignancy by invading the tissue affected.
15% multiorgan involvement.
If untreated 90% will dye in 10 yrs of developing symptoms.
1. a collapsing elliptical cyst.
2. detachment of the germinal layer from the cyst wall
(water lilly sign).
3. calcification of the rim (eggshell appearance).
or by chemotherapy.
A systematic review of the literature published in 2004 concluded that chemotherapy alone is not a successful approach and that it needs to be combined with either percutaneous drainage or surgery which remain the cornerstone of treatment.
Dziri C, Haouet K, Fingerhut A.
Treatment of hydatid cyst of the liver: where is the evidence?
World J Surg 2004; 28 (8):731-6.
Peroxide soliution 10% (foaming, gas embolism).
Hypertonic saline 10%-20% for 5-10 min.
Cetrimide 0.4%-1% for 4-10 min.
Avoid using these materials in suspected communications, so not to be used routinely.