THE AMOEBAE 



147 



appeared identical with E. chattoni of 

 monkeys; this is the species to which their 

 form should be assigned. Ten human in- 

 fections have been reported (Kessel and 

 Johnstone, 1949; Lawless, 1954; Burrows 

 and Klink, 1955). However, altho no 

 human cross-infection experiments have 

 been attempted, E. suis does not seem to 

 be readily transmissible to man. Chang 

 (1939) observed that it was not present in 

 27 Chinese butchers, altho their methods of 

 slaughtering provided ample opportunity for 

 infection. Pavloff (1935) was unable to in- 

 fect kittens with it by intrarectal inoculation. 



E. suis has been described by a num- 

 ber of authors, including Noble and Noble 

 (1952) in domestic animals, and by Bur- 

 rows (1959) in man. The following des- 

 cription is based on Noble and Noble. 

 The trophozoites are 5 to 25fi long. Some 

 authors (e. g. , Hoare, 1959; Simitch et al. 

 1959) have considered the small forms to 

 be a separate species, E. debliecki, but 

 such a separation does not appear to be 

 justified. 



The nucleus varies in appearance. 

 The endosome is central and is usually 

 quite large. It may sometimes almost fill 

 the nucleus, but it may also sometimes be 

 small and similar to that of E. histolytica. 

 There is a rather homogeneous ring of 

 peripheral chromatin within the nuclear 

 membrane. There are ordinarily no 

 chromatin granules between the endosome 

 and the peripheral ring. The cytoplasm 

 is granular and vacuolated, and contains 

 bacteria in its food vacuoles. The cysts 

 are 4 to 17 ju in diameter and have a 

 single nucleus when mature. The chroma- 

 toid bodies in the cysts vary markedly in 

 shape from stout rods with rounded ends 

 similar to those of E. histolytica to irreg- 

 ular granules of varying size. There may 

 or may not be a glycogen vacuole. Cysts 

 without chromatoid bodies or glycogen 

 vacuoles are also common. 



(1934) observed amoebae associated with 

 necrosis in sections of the colon of pigs 

 which had died of experimental hog chol- 

 era. However, altho E. suis is very 

 common in swine, it has never been found 

 in sections of intestinal lesions of hundreds 

 of swine examined by University of Illinois 

 pathologists. 



E. suis can be cultivated in the usual 

 media. It is apparently less sensitive 

 than E. histolytica to amoebicidal drugs, 

 but Frye and Meleney (1932) eliminated it 

 from pigs by feeding 50 mg/kg carbarsone 

 in the milk daily for 10 days. 



ENTAMOEBA BUBALUS 

 NOBLE, 1955 



Noble (1955) found this species in the 

 feces of 12 of 15 carabao (Bubalus bubalis) 

 from several islands in the Philippines. 

 Only 2 trophozoites were seen. They 

 averaged 12 /ii in diameter. The cysts are 

 5 to 9 fi in diameter with a mean of 8 jll . 

 They contain 1 or more vacuoles, but 

 usually a single large one which crowds 

 the cyst contents to its periphery. The 

 chromatoid bodies are usually small and 

 irregular in shape but may occasionally 

 be large, with rounded ends, similar to 

 those of E. histolytica. The cysts contain 

 a single nucleus 2. 6ju in diameter with a 

 large endosome 1.4jj. in diameter which 

 often appears to be a cluster of 4 granules. 

 There is usually a distinct peripheral ring 

 of chromatin, but the amount of peripheral 

 chromatin may vary from practically none 

 to a ring of dots to a few isolated clumps. 

 There is no periendosomal chromatin. 

 Noble (1955) considered E. bubalus to 

 differ from other entamoebae with uninu- 

 cleate cysts in the character of its nucleus-- 

 the heavy, usually uniform outer ring of 

 chromatin and the large, prominent endo- 

 some. 



E. suis is probably non- pathogenic. 

 Smith (1910) found amoebae in sections of 

 intestinal ulcers in swine. Hartmann 

 (1913), who studied Smith's preparations, 

 named the amoeba E. suis. Ratcliffe 



ENTAMOEBA CHATTONI 

 SWELLENGREBEL, 1914 



parte. 



Synonym : Entamoeba polecki, pro 



