An erratic parasitism found in the lungs of sheep during experimental infection with Fasciola gigantica (Japanese strain).

An erratic parasitism was observed in the lungs of sheep experimentally infected with Fasciola gigantica at autopsy 14 weeks after inoculation. Macroscopically, several hyperaemia of 7.5-12.5 mm in diameter were found on the surface of the lungs. Juvenile flukes detected in the lungs were much smaller than those in the liver of the same sheep. A slight inflammatory reaction was observed in the lungs and it is likely that the flukes had migrated in the pleural cavity for some time. Occasionally, a mixed thrombus with many eosinophils was found in the blood vessels adjacent to the bronchia, although no cough was observed clinically. This suggests that diagnosis of juvenile fluke is difficult not only by parasitological but also serological methods.