33 



in alimentary canal of earth worms and thus be transferred to 

 chickens. 



Symptoms of the disease — Chief symptom the "yawning" or 

 "gaping" with widely opened beak and straining forward of the 

 neck. Wheezing cough and frothy sajiva sometimes to be noted. 



Prophylaxis — Remove all fowls known to be infected; bury 

 deeply or, better, burn heads and necks of all dying from the disease. 

 Disinfect houses and runs with one per cent solution of sulphuric 

 acid or by heat. Frequent change of yards, and care to have yards 

 in dry clean places will do much to lessen disease. Mechanical 

 removal of parasites from trachea unsatisfactory. 



Family TRICHOTRACHELIDAE 



Trichinella spiralis — (Trichina spiralis). The cause of trichinosis, 

 a serious disease of man caused by eating pork infested with the 

 larvae of this worm. See Leuckart, '66; Ransom, '07; Stiles and 

 Hassall, '01. 



Description — Adults inhabit the small intestine of man, hogs, 

 rats, and various other mammals for a short period after ingestion 

 of infested meat. Very small, barely visible to the naked eye. 

 Males 1.4-1.6 mm. in length, no spicules, but with two conical caudal 

 appendages, behind which are four papillae. Females 3-4 mm. in 

 length, viviparous, possess but one ovary; vulva ventral in anterior 

 fifth of body. 



Life history — Female is fertilized while in the intestine of host 

 and soon begins to produce young, — 1,500 or more, each — which 

 both by active migration and by transfer by the lymph or blood are 

 distributed throughout the entire body. Begin to reach the striated 

 muscles about the tenth day after infection, and up to the eighth 

 week enter fibers and there encyst. Lemon shaped cysts, formed by 

 modified tissues of host, each containing a coiled sexual larva. An 

 ounce of badly infested meat may contain 4,000 cysts. Cysts may 

 become calcified and larvae remain alive in them for many years. 

 When the infested flesh is eaten the larvae are released and obtain 

 sexual maturity in two days. 



Symptoms of trichinosis in man — Severity of symptoms depends 

 on number of larvae ingested. While in the intestine, may cause 

 gastro-intestinal irritation, nausea, abdominal pains, diarrhoea and 

 fever. From the seventh to the tenth day and later, the migrating 



