Immunotherapy of post-surgical alveolar hydatid disease (AHD)

Abstract

Immunotherapy of post-surgical Alveolar Hydatid Disease (AHD) was attempted using an attenuated strain of Mycobacterium bovis (BCG) in this study. Gerbils were subcutaneously infected with Echinococcus multilocularis. Ninety days later the established subcutaneous cyst mass was surgically removed in three groups of gerbils that had been administered with either BCG (a macrophage activator), Carrageenan (CAR) (an anti-macrophage agent) or saline 10-12 days before the operation. In the fourth group of gerbils the established cyst was left intact. At necropsy 30 and 60 days post-surgery, body regions with disseminated cyst foci were recorded and metastatic cyst weights taken in all the experimental groups. Cyst tissue samples were taken for histology and blood smears were examined for differential white blood cell counts. Metastasis occurred mostly to the draining lymph nodes suggesting that germinal tissue was disseminated mostly via the lymphatic vessels. All four treatments groups did not show any significant difference in their levels of metastasis. Histological appearance of the qualitative leucocyte cellular response towards the parasite was similar in all the groups. It is suggested that BCG does not have an enhancing effect on macrophages already suppressed by the chronic parasitic infection. In fact macrophages may be further suppressed, thus not controlling post-surgical growth of metastatic foci.