Clinical value of Echinococcus granulosus--specific immunoglobulin G antibody avidity in liver cystic echinococcosis

Role of E. granulosus-specific IgG antibody avidity in evaluation of a natural history of the parasite cysts in the liver, duration of infection and immunogenic cysts activity was studied. Thirty-one patients with liver cysts suspected of echinococcosis were examined; E. granulosus infection was finally confirmed by a fine needle aspiration biopsy or surgery in 29 cases (93.5%) and two non-parasitic simple cysts in the liver were diagnosed. E. granulosus-specific IgG antibody was found in 21 patients (67.7%). High IgG avidity values were observed in 14 patients with liver cysts in a degeneration stage confirmed by imaging techniques. Low IgG avidity values were mostly detected in children with hypoechogenic echinococcal cysts being in a recent stage of infection. Determination of anti-E. granulosus immunoglobulin G antibody avidity is a very usefull diagnostic tool for a determination of parasitic cysts activity and their developmental age.