148 



THE AMOEBAE 



This species occurs in the large in- 

 testine of macaques and a number of other 

 monkeys. It was first seen by Chatton 

 (1912), who called it Loeschia sp. , and 

 was given its present name by Swellengre- 

 bel (1914), who found it in the rhesus 

 monkey. This name was thought to be one 

 of the many synonyms of E. histolytica 

 until Salis (1941) showed that it was not. 

 Kessel and Johnstone (1949) found E. 

 chattoni and E. polecki to be morphologi- 

 cally similar, and used the older name, 

 E. polecki, for the species. However, 

 in the absence of cross-infection exper- 

 iments between pigs and monkeys, it is 

 best to retain the name, E. cliattoni, for 

 the monkey form. In any case, E. polecki 

 is a nomen nudum and should be replaced 

 by E. suis. The proper name for the 

 forms in the 10 human cases which have 

 been reported (see Burrows and Klink, 

 1955) is uncertain. Perhaps it should de- 

 pend in each case on the source of infec- 

 tion, whether pig or monkey, or perhaps 

 both these names will eventually be 

 dropped in favor of E. bovis. However, 

 for the present E. chattoni is preferable. 



E. chattoni is probably much more 

 common in monkeys than E. histolytica, 

 from which it must be distinguished. 

 Mudrow-Reichenow (1956) found it in 6 of 

 7 rhesus monkeys in Germany. The 

 trophozoites of E. cliattoni are 9 to 25 /i 

 long. The cysts are 6 to 18fi in diam- 

 eter. Salis described two size races 

 with cysts averaging 10. 9 and 13. 1 fj. , 

 respectively but other workers have not 

 made this differentiation. The nucleus 

 varies a great deal in morphology. It 

 may be indistinguishable from that of E. 

 histolytica, with a small, central endo- 

 some and a row of fine, peripheral chro- 

 matin granules. On the other hand, the 

 endosome may be large or small, central 

 or eccentric, compact or diffuse, and 

 composed of one to many granules, while 

 the peripheral chromatin may be fine or 

 coarse, uniform, irregular or diffuse, 

 and there may or may not be chromatin 

 granules between the endosome and the 

 peripheral chromatin. The cysts are 

 almost always uninucleate when mature. 

 Less than 1% are binucleate, and they are 

 never tetranucleate. The chromatoid 



bodies are usually irregular and small, 

 but may also be rod-shaped with round or 

 pointed ends, oval or round. A glycogen 

 vacuole may or may not be present. 



E. cliattoni is generally considered 

 non- pathogenic, altho 2 of the human pa- 

 tients studied by Burrows and Klink (1955) 

 had diarrhea which may or may not have 

 been caused by the amoebae. 



ENTAMOEBA GINGIVA LIS 

 (GROS, 1849) 

 BRUMPT, 1914 



Synonyms : Amoeba gingivalis , 

 Amoeba buccalis. Entamoeba buccalis. 

 Amoeba dentalis. Amoeba kartulisi, Enta- 

 moeba maxillaris. Entamoeba canibuc- 

 calis. 



This species occurs commonly in the 

 human mouth, where it lives between the 

 teeth, in the gingival margins of the gums 

 and in the tartar. It has occasionally been 

 found in infected tonsils. E. gingivalis 

 is present in perhaps 50% of all humans, 

 but in up to 95% of those with pyorrhea. 

 It was once thought to be the cause of 

 pyorrhea, but is now known to be a harm- 

 less commensal which finds an ideal home 

 in diseased gums. 



Hinshaw (1920) transmitted E. gingi- 

 valis to 5 dogs with gingivitis. In one of 

 them the infection was still present after 

 14 1/2 months, but in the others it died 

 out within 4 months. Kofoid, Hinshaw and 

 Johnstone (1929) established persistent in- 

 fections in 5 of 11 dogs with E. gingivalis 

 from cultures. They could not infect dogs 

 with healthy mouths, but only those with 

 gingivitis, pus pockets or loose gums. 



Goodrich and Moseley (1916) found 

 amoebae indistinguishable from E. gingi- 

 valis in pyorrheic ulcers in the mouths of 

 2 dogs and a cat in England. N6ller(1922) 

 found it in dogs in Germany. Simitch 

 (1938) found a small amoeba in the saliva 

 of 3 out of 165 dogs in Serbia and named 

 it E. canibuccalis. The trophozoites 

 were 8 to IGja long but became as long as 

 2 5 /J in culture. Simitch infected 2 old 



