312 



DISEASES DUE TO HELMINTHS 



OXYURIASIS. 

 THE PARASITE. 



The Oxyuris vermicularis or thread-worm is world-wide in its 

 distribution and occurs only in man. 



M 



A, male and B, 

 female, of Oxyu- 

 ris vermicularis. 



5/1- 



'Si^-fpiW 



On the left, female ; on the 

 right, male. A, anus; M, 

 mouth : V, vulva. Greatly 

 enlarged. (After Ciaus.) 



Oxyitiis vermicu- 

 laris : egg freshly de- 

 posited, with tadpole- 

 like embryo. X 640. 



Oxyuris vermicu- 

 laris : egg twelve 

 hours after deposition, 

 with nematode- like 

 embryo. x 640. 



The male is 3 to 5 mm. long and the female 9 to 11 mm. long. 



They live in the lower part of the small intestine but the gravid 

 females migrate to the caecum, colon and anus. The males die after 

 copulation. 



The eggs are given off in the gut and measure 30 by 20 ^l■ 



They have a thin shell and contain a well developed embryo when 

 the egg is passed in the fasces. These eggs escape and are re-intro- 



