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Echinococcosis is a parasitic disease of tapeworms of the Echinococcus type characterized by production of unilocular or multilocular cystic disease of lung and liver.
Classification
A. Cystic echinococcosis (M/C)
- Also known as, unilocular echinococcosis
- Caused by Echinococcus granulosus sensu lato
B. Alveolar echinococcosis (#2 M/C)
- Also known as alveolar colloid of the liver, alveolar hydatid disease, alveolococcosis, multilocular echinococcosis, “small fox tapeworm”
- Caused by Echinococcus multilocularis
C. Polycystic echinococcosis:
- Also known as human polycystic hydatid disease, neotropical echinococcosis
- Caused by Echinococcus vogeli and very rarely, Echinococcus oligarthrus.
Epidemiology
Life cycle

Pathology
Hydatid cyst:
hydatid cyst is composed by two parts: the echinococcal parasite (or hydatid) and the adventitia that involves it, as Devé defined in the beginning of the last century (1911), and there is no reason or legitimacy to modify this definition. The adventitia is a layer of an inert tissue with fibrosis and variable thickness, which results from the host’s organ reaction against the hydatid, which is a foreign body. This layer can be called periparasitic or perihydatidic area, but never pericystic area, as it is sometimes wrongly named, because it is an integrant part of the cyst. An example of this common mistake is the use of the term “pericystectomy” for the excision of a cyst, when removing the adventitia. This term misleads you into thinking that this layer (adventitia) is not part of the cyst, assuming that the cyst includes only the parasite (hydatid) and not the adventitia, which is wrong and opposite to Devé’s definition

Ultrasound (US) classification:
In 1981, Professor Gharbi et al. proposed a US classification of the hydatid cysts according the natural evolution of the parasite. In 1995, the Informal Working Group on Echinococcosis (IWGE-WHO) proposed the standardization of the US classification now known as WHO classification.

Clinical feature
Symptoms occur due to mass effect of the cysts and are related to the organ in which they occur.
- Liver cysts:
- Abdominal pain & palpable mass
- Lung cysts:
- Chest pain, hemoptysis and breathlessness
- Hydatid disease of the kidneys:
- Hydatiduria
- Passage of cysts in the urine
- Hematuria following hydatiduria
- Hydatiduria
Complications:
Rupture or leakage from a hydatid cyst
- Fever
- Itching
- Rash
- Anaphylaxis
- Dissemination of infectious scolices
Diagnosis
- Ultrasonography (USG) and CT scan
- Internal membranes of cyst
- Floating ectogenic cyst material (hydatid sand)
- Daughter cysts within the parent cyst
- Diagnostic aspiration
- Generally contraindicated because of risk of infection and anaphylaxis
- ELISA
- Antibody detection
Management
Treatment
Medical management
- Albendazole or Mebendazole
PAIR (puncture-aspiration-injection-reaspiration):
First line management of hydatid cysts. Contraindicated in dead, calcified, deep-seated or multiloculated cysts
- Puncture of cyst under image guidance
- Aspiration of cyst contents
- Instillation of hypertonic saline into cyst cavity
- Reaspiration of the solution
Surgical management
- Liver resection
- Local excision of cysts
- Deroofing + evacuation of contents
Prevention:
- Proper cooking practices
