Echinococcosis, also called hydatid disease, hydatidosis, or echinococcal disease is a chronic disease effecting humans and animals and is caused by a parasitizing helminths Echinococcus (...)
Echinococcosis, also called hydatid disease, hydatidosis, or echinococcal disease is a chronic disease effecting humans and animals and is caused by a parasitizing helminths Echinococcus granulosus. Echinococcosis is widespread throughout the world, especially in southern countries where livestock breeding takes place but particularily is associated with sheep farming.
Echinococcus eggs enter the body through dirty hands as a result of contact with dogs (more rare- with cats). Infection is also possible after eating unwashed vegetables, berries, and fruits, as well as drinking water contaminated with the helminth eggs.
The eggs of Echinococcus are released from the shell in the digestive canal of an intermediate host. The embryo (hexacanth) penetrates into the small intestine mucosa, and reaches through the lymphatic and venous vessels into the portal vein system. As a result, hexacanths gain access to internal organs, and in most cases, develop into echinococcal cysts. The liver (44-85% of cases) and lung (10% of cases) are the most affected organs.
The pathological effect of Echinococcus is caused by an organism response to products of parasite metabolism and mechanical damage of affected organs and tissues. Dimensions of cysts can vary from 1-5 cm in diameter to large bubbles, which can contain several litres of fluid.
Mechanical effects of cysts can lead to the dysfunction of an affected organ and its hypertrophy.
To diagnose echinococcosis, techniques used for imaging cysts can include X-ray, ultrasound, computerised and magnetic resonance imaging. Needle biopsy of cysts is considered to be dangerous because of the possibility of spreading parasites to adjoining tissue.
Detection of specific antibodies to Echinococcus antigens in blood is a reliable indicator of a parasite infestation. The level of immune response largely depends on organ localization of a cyst and its morphology. Low levels of antibodies are observed at the beginning of cyst formation or in the inoperable late stages of the disease.
For the detection of antibodies specific to Echinococcus granulosus, methods of indirect hemagglutination, immunofluorescence, and ELISA are used. These methods have a sensitivity of 60-90%, therefore by combining serological methods more information can be obtained.
Serological methods are quite informative for monitoring the postoperative condition of the patient. A gradual reduction of specific antibodies 4-6 months after surgical removal of the cyst indicates a favourable outcome of the surgery. If cysts recur antibodies remain at a high level in blood for years.