Protozoa of the Digestive and Urogenital Tracts 551 



the mucosa. Symptoms include chronic diarrhea, attacks of diarrhea 

 alternating with constipation, chronic stomachache, occasional cramping 

 and colic, nausea, abdominal tenderness, loss of appetite, chronic head- 

 aches, and irritability (61, 111, 178). 



Chemotherapy 



The treatment of flagellate infections is a less pressing problem 

 and has attracted less attention than the treatment of amoebiasis. Some 

 of the drugs used for Entamoeba histolytica have been tried also in 

 flagellate infections, but the results are not always directly comparable. 

 Atebrin has been used effectively for elimination of Giardia lamblia, 

 although occasional infections are not cured. Giardiasis in children also 

 has been treated with bismuth-salicylate, followed by treparsol (111), 

 and with acranil (16). Diodoquin is said to be active against P. hominis, 

 and good results with gentian violet in combination with argyrol enemas 

 also have been reported. 



AMOEBAE OF THE INTESTINAL 

 LUMEN 



The human colon may be invaded by Endolimax nana, Dienta- 

 moeba fragilis, Entamoeba coli, and lodamoeba biltschlii. In addition, 

 natural infection with Entamoeba polecki, a. parasite of monkeys, has 

 been observed (88). 



Endolimax nana 



(Wenyon and O'Connor) Brug 



First described as Entamoeba nana (179), this species was later 

 transferred to the genus Endolimax by Brug in 1918. An apparently 

 identical amoeba has been reported from monkeys (46). 



The amoeboid stage (Fig. 11.4, A), usually observed only in loose 

 stools, is a small (6-15[j,) sluggish form with clear pseudopodia and food 

 vacuoles containing bacteria. The stained nucleus often shows no periph- 

 eral granules, although such can be demonstrated after adequate fixation 

 (155). The endosome is large, usually irregular but sometimes ovoid or 

 spherical, and may be central or eccentric. Precystic stages have been 

 reported as rounded forms without food vacuoles. Mitosis has been de- 

 scribed (49a). 



The mature cysts (Fig. 11. 4, B-E), 5-12x4-6[jl, contain four, or rarely 

 eight, nuclei. The shape is usually ovoid, and one surface is often more 

 convex than the opposite side. Stored glycogen may be present in young 

 cysts but disappears gradually as the cysts mature. Occasionally, small 

 filaments have been reported as possible chromatoid bodies. The nuclei 

 of the mature cyst are appreciably smaller than those of the trophozoite, 

 and the endosome is often eccentric. 



