158 



DISEASES DUE TO ANIMAL PARASITES 



quiescent the eosinophilia may disappear (Cabot). Cabot states 

 that the characteristic blood lesions change trichinosis from the 

 position of a disease very difficult and uncertain of diagnosis 

 (without excision of a bit of muscle) to one whose recognition is 

 usually easy. Opie in an experimental study fed pork containing 

 different numbers of trichina larva? to guinea pigs and obtained 

 the following results: "The administration of trichina spiralis to 

 the guinea pig causes an increase of the eosinophile leucocytes 



in the blood, comparable 

 to that which accompanies 

 human infection. There is 

 no constant alteration of 

 the number of these cells 

 until the end of the second 

 week after infection, when 

 their relative and absolute 

 number rapidly increases 

 and reaches a maximum 

 at the end of the third 

 week. At this time em- 

 bryonic trichina? arc in 

 process of transmission 



from the intestinal mucosae 



Fig. 23. bdnrin t in mitts in blood, doq. , ^,11 1 



by way of the lymphatic 



vessels and the blood through the lungs to the muscular system." 

 Drake examined the blood of 15 swine, the muscle of which he 

 had found contained larval trichina?, and found that there was 

 no increase in the numbers of eosinophiles. The blood contained 

 the following percentages of leucocytes: lymphocytes 53-72, aver- 

 age 63.2; polynuclears 26-42, average 32.7; eosinophiles 0.5-10, 

 average 4.03. He concludes that there is in swine trichinosis no 

 increase in the percentage of eosinophiles. Another explanation, 

 however, is possible, that his examinations were made in a stage 

 too late to show the increase. 



Filariasis. — In an old dog much emaciated and showing marked 

 ascites, Burnett and Traum found larvae of Filaria immitis in the 

 peripheral blood. The blood examination gave the following: red 

 corpuscles 2,642,000, hemoglobin 57, leucocytes 24,590. Of the 

 leucocytes there were lymphocytes 8%, large mononuclears 7%, 



