Final localization of Schistosoma japonicum in the lungs of field rats, Rattus mindanensis, in Leyte, Philippines.

Among 45 specimens of Rattus mindanensis (Hearns, 1,905) caught in an endemic area of schistosomiasis japonica in Leyte, Philippines, 39 (86%) were found to be positive for Schistosoma japonicum. Lung examination of 24 autopsied rats revealed a high incidence of pulmonary infection and the flukes were found in 20 rats (83%). In 24 (73%) out of 33 rats, the flukes were seen in the hepatic portal vein. Only 29% of the rats were positive for Schistosoma ova in the intestinal wall. The average number of living worms was much greater in the lungs (19.2) than in the liver (12.4). However, fewer fully developed worms of oviposition stage were found in the lungs than in the liver. In the lungs widespread and massive nodules containing living worms and distinct lesions due to embolism were observed histopathologically.