Secondary echinococcosis is an important complication of hydatid disease and is not rare in the peritoneal cavity. However, the frequency of secondary hydatidosis in the pleural cavity is not very well known. This study was planned to elicit the frequency of secondary cyst development in the pleural cavity, and to compare this with secondary peritoneal hydatidosis. It was also intended to follow up cyst development by serological tests. Twelve white female Island rabbits were used. The mean weight of the rabbits was 2450±420 g. Cystic fluid containing protoscolex, hydatid sand and germinative membrane homogenate was injected via an 18 F needle into the pleural and peritoneal cavities of the rabbits. At the begining and the fourth and fifteenth weeks of the study, 5 cc of blood was withdrawn from the ear veins of the rabbits for serological investigations. All rabbits were sacrified by cervical dislocation at the end of the fifteenth week of the study. Peritoneal and pleural cavities were opened and examined for secondary cyst development. Serological investigations were performed with indirect hemaglutination and indirect flourescein antibody tests. The frequency of secondary echinococcosis in the peritoneal cavity was 80% and, in the pleural cavity 30 %. In determining the antibodies against the hydatid antigens the indirect flourescein antibody test was more sensitive than the indirect hemaglutination test. The occurence of secondary echinococcosis is possible in the pleural cavity, but to a lesser degree than in the peritoneal cavity. Indirect hemaglutination and indirect flourescein antibody tests were found to be valuable serological tools for the diagnosis of hydatid disease. Hydatid cyst, secondary echinococcosis, pleural and peritoneal cavities, IHA and IFA tests.

Secondary echinococcosis is an important complication of hydatid disease and is not rare in the peritoneal cavity. However, the frequency of secondary hydatidosis in the pleural cavity is not very well known. This study was planned to elicit the frequency of secondary cyst development in the pleural cavity, and to compare this with secondary peritoneal hydatidosis. It was also intended to follow up cyst development by serological tests. Twelve white female Island rabbits were used. The mean weight of the rabbits was 2450±420 g. Cystic fluid containing protoscolex, hydatid sand and germinative membrane homogenate was injected via an 18 F needle into the pleural and peritoneal cavities of the rabbits. At the begining and the fourth and fifteenth weeks of the study, 5 cc of blood was withdrawn from the ear veins of the rabbits for serological investigations. All rabbits were sacrified by cervical dislocation at the end of the fifteenth week of the study. Peritoneal and pleural cavities were opened and examined for secondary cyst development. Serological investigations were performed with indirect hemaglutination and indirect flourescein antibody tests. The frequency of secondary echinococcosis in the peritoneal cavity was 80% and, in the pleural cavity 30 %. In determining the antibodies against the hydatid antigens the indirect flourescein antibody test was more sensitive than the indirect hemaglutination test. The occurence of secondary echinococcosis is possible in the pleural cavity, but to a lesser degree than in the peritoneal cavity. Indirect hemaglutination and indirect flourescein antibody tests were found to be valuable serological tools for the diagnosis of hydatid disease. Hydatid cyst, secondary echinococcosis, pleural and peritoneal cavities, IHA and IFA tests.