Recent trends in the serodiagnosis of hydatid disease.

Hydatid disease caused by Echinococcus granulosus is a zoonotic infection of cosmopolitan distribution. As the clinical manifestations of hydatid disease in man are variable, the diagnosis of the condition presents complex problems for clinicians. Since the parasitic diagnosis of the disease is difficult, the specific diagnosis of the condition relies heavily on immunodiagnostic tests. The recent approach to the diagnosis of hydatid disease in man is primarily based on: (1) a combination of two or three more serological tests to diagnose the condition, as a single test fails to detect all the cases, (2) detection of circulating hydatid antigen (CAg) in the serum by enzyme-linked immunosorbent assay (ELISA) and other assays, as the antigen detection system is useful in monitoring post-surgical and chemotherapeutic evaluation of the cases as well as in the prognosis of the condition and (3) demonstration of E. granulosus antigen in the cystic fluid to establish the etiology of the hydatid cyst. Hydatid disease is essentially a disease of poor people residing in rural areas, hence there is need for a simple, economic diagnostic immunoassay for use at the field level or in a rural health center with inadequate facilities. Counter-current-immunoelectrophoresis (CIEF) and bacterial co-agglutination (Co-A), have been standardized and evaluated in this laboratory for the first time for detection of CAg in cases of hydatid disease at the field level and rural health center.