Echinococcosis is a parasitic disease of tapeworms of the Echinococcus type characterized by production of unilocular or multilocular cystic disease of lung and liver.
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
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