Echinococcus granulosus

Echinococcosis is a chronic disease of humans and animals caused by parasitizing the larvae of the helminth Echinococcus. The causative agent of this helminthiasis is most often the larva of Echinococcus granulosus. Echinococcosis is quite common all over the world, especially in southern countries, where livestock breeding, mainly sheep breeding, is widespread.

Echinococcus eggs enter the human body through dirty hands after contacting dogs (less often - cats). Also, infection is not excluded when eating unwashed vegetables, berries, fruits, water that are contaminated with helminth eggs.

In the digestive canal of the intermediate host, the egg of the echinococcus is freed from the membrane, and the embryo (oncosphere) deepens into the mucous membrane of the small intestine, entering the internal organs, where, in most cases, they linger and develop into echinococcal cysts. More often, echinococcus affects the liver (in 44-85 % of cases) and lungs (10 % of cases).

The pathological effect of echinococcus is due to the sensitization of the body by the metabolic products of the parasite and mechanical damage to the affected organs and tissues. The sizes of cysts are from 1-5 cm in diameter to large blisters, which can contain several liters of fluid. The mechanical effect of such a cyst leads to dysfunction of the affected organ, its hypertrophy.

To diagnose echinococcosis, cysts visualization methods are used: X-ray and ultrasound studies, computed and magnetic resonance imaging. Puncture biopsy of a cyst is considered dangerous due to the possibility of spreading parasites into adjacent tissues.

The detection of antibodies specific to the antigens of echinococcus in the blood is a reliable indicator of parasite invasion. The level of the immune response largely depends on the organ localization of the cyst and its morphology. Low antibody levels are observed at the onset of cyst formation or at a late inoperable stage of the disease.

Today, methods of indirect hemagglutination and fluorescence, enzyme immunoassay are used to detect specific antibodies to Echinococcus granulosus. These methods are characterized by a sensitivity of 60-90 %, therefore, the best information content is achieved using a combination of serological methods.

Serological methods are also quite informative for monitoring the patient’s postoperative state - a gradual decrease in the level of specific antibodies 4-6 months after surgical removal of the cyst indicates a successful result of the surgical intervention. With relapses of cyst formation, specific antibodies are kept at a high level for years.