ASCARIASIS 



309 



PROPHYLAXIS. 



All rats near to pigsties must be destroyed. 



Pigs must be kept away from the offal of slaughter houses. 



Meat should be cooked at a temperature of 62° to 7o°C. in all parts. 



In some sausages the pork is uncooked. Such pork should be 

 examined, passed and marked by an inspector qualified for the work. 

 The parts affected chiefly are the tongue, laryngeal muscles, diaphragm 

 and abdominal muscles. To search for the cysts press a small portion 

 of the muscle fibre between two translucent glasses or plates when the 

 larvas are more readily seen. 



The larvae are not killed by freezing, and hence frozen meat may 

 be infected. 



ASCARIASIS. 

 DEFINITION. 



This is an infection usually with the Ascaris lumbricoides or round 

 worm, rarely with the Toxascaris canis or Belascaris. 



The two latter are smaller and are more commonly found in cats 

 and dogs. 



DISTRIBUTION. 



In all tropical and sub-tropical climates. 



The A. lumbricoides is parasitic only in man. When the eggs are 

 passed externally their development is limited until re-introduced into 

 man . 



THE PARASITE. LIFE-HISTORY. 



The eggs are laid in the small intestine and measure from 50 /ti to 

 JO ju, by 40 ya 10 50^- They have a thick yellow transparent shell coated 



/^"P^^^'i 



"%«x::^ 



Ascaris lumbricoides. a, posterior extremity of Ov\xn\oi Ascaiis lumbricoides, 



the male witii the spicules protruding from the with shell and albuminous en- 



orifice of the cloaca {Sp.) ; b, anterior extremity velope. 400/1. 



from the dorsal surface, the two lobes of the pulp 

 of the lip separated by the " saddle " ; c, anterior 

 extremity from the ventral surface ; P., excretory 

 pore. (From Claus.) 



irregularly Avith albumin and stained a brownish yellow by fcecal 

 material. This outer covering may be removed during the passage 

 through the intestine. The shell affords high resistance to changes 

 in temperature and moisture. The contents are granular but do not 

 divide into nuclei as in the &gg of the ankylostome. 



