VIII, B, 5 Walke7-: Experimental Balantidiasis 335 



recent cases in the Philippines has been up to the present time 

 4, or 7 per cent, but most of these are latent cases without 

 symptoms. 



The pathological changes in balantidiasis, as reported in the 

 literature of 40 necropsies, showed ulcerations of the large intes- 

 tine in 36, chronic catarrh in 3, and in 1 case the condition of the 

 large intestine was not given. The ulcers are said not to be 

 characteristic. The old ulcers are described as blackish or slate- 

 colored and the recent ulcers are frequently slightly undermined 

 and irregular. The mucosa between the ulcers in usually red- 

 dened and hsemorrhagic. In only 1 case (Peterson, 1873) has 

 an ulcer been reported in the ileum. The parasites were found 

 in the contents of the large intestine at necropsy in 21 of the 

 cases. In all of these cases the ulcerative lesions were probably 

 complicated by secondary bacterial invasion. 



Histological studies of the lesions in balantidiasis have been 

 made in a few of the fatal cases, notably by Strong and Musgrave 

 (1901), Solowjew (1901), Bowman (1909 and 1911), and Bel 

 and Couret (1910). The principal changes recorded are catarrh 

 of the mucosa, cell degeneration and necrosis, polymorphonuclear 

 infiltration (probably due to secondary invasion of the lesions 

 by bacteria) , hypertrophy of the vessels, haemorrhages, round cell 

 infiltration, eosinophilia, and penetration of the parasites into 

 the sound tissues underlying the ulcers. The balantidia were 

 found in the submucosa, muscularis, in the mesocolic lymph 

 glands, and in the blood vessels and lymph spaces, lying singly or 

 in groups. 



Unlike infections with Entamoeba histolytica, liver abscess does 

 not appear to be a common complication in balantidiasis; but 

 Stockvis (1884) reported a case in which the balantidia were 

 found in the sputum of the patient and were believed to have come 

 from a liver abscess which had ruptured into the lung. The 

 patient recovered, therefore no necropsy was obtained. 



Besides man, monkeys and pigs are known to be naturally 

 parasitized with balantidia. 



Brooks (1902) reported an epizootic of dysentery among the 

 apes in the New York Zoological Park due to balantidial infection. 

 Noc (1908) found a case of balantidial dysentery in Macaciis 

 cynomolgus at the Pasteur Institute in Saigon, Indo China. 

 Brumpt (1909) reports 6 cases of natural parasitization of 

 Macaciis cynomolgus with balantidia in Indo China. 



Balantidia were first observed as parasites of the domesticated 

 pig by Leuckart (1861 to 1863). They have been found by 



