278 



OTHER INTESTINAL ROUNDWORMS 



fifths of an inch in length, and have about the diameter of an 

 ordinary pin. The. males (Fig. lll(J)_are only about half as 

 large and have the posterior end of the body rolled ventrally. 



The adult females filled with eggs leave 

 the small intestine and coecum and wander"" 

 back to the rectum whence they are" 

 passed out with the faces or creep out 

 of the anus, especially in the evening 

 or at night, causing intense itching. 

 These egg-filled females, or the free eggs 

 which already contain coiled embryos, 

 live in the moist groove between the 

 buttocks, in girls sometimes creeping for- 

 ward to the vagin% From the scratching 

 and rubbing which results from the itch- 

 ing in the vicinity of the anus the fingers 

 and fingernails become infected with the 

 eggs. The eggs may then be transferred 

 to the mouth directly or indirectly, thus 

 causing reinfection, or they may be trans- 

 mitted from person to person by unclean 

 hands. ^Infection may also occur by 

 swallowing the mature egg-filled female 

 OxTuru\ermi^Zi.-^: worms, or by the eating of raw vegetables 

 female; $, male; ph., or othcr foods which havc been polluted 



pharynx; int., intestine: , ^j^^ ^g '; ^g -^^ ^^le CaSC of Other 

 ov., ovary; ut., uterus; an., '' ®° - . . 



anus; v., \aiiva; t., testis; parasite cggs, thosc of the pihwomi may' 

 IX^^^'cZTir^rJ^^ ^l«P~be scattered by flies which have 



visited infected fseces. 



When first deposited, the eggs, often hanging together like 

 short strings of beads, contain larvae which resemble tadpoles 

 (Fig. 11 2A). In the faeces or in the moist groove between the 

 buttocks the larvae, still in the eggs, transform within a few hours 

 into worms of typical nematode form (Fig. 112B). Later stages 

 are shown in Figs. 112C and D. 



After infection, which probably nearly always occurs by way 

 of the mouth, about two or three weeks elapse before sexual 

 maturity is again attained and the eggs and females reappear 

 in the faeces. 



Whileusually no inconvenience is felt from the presence of 



