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UNITED STATES DEPARTMENT OF AGRICULTURE 



MISCELLANEOUS PUBLICATION NO. 79 



WASHINGTON, D. C. MAY, 1930 



ANTHELMINTICS FOR THE REMOVAL OF 

 THORN-HEADED WORMS FROM SWINE 



By Willard H. Wright and H. B. Raffensperger, Associate Veterinarians^ 

 Zoological Division, Bureau of Animal Industry 1 



CONTENTS 



Page 



Introductory note 1 



The life cycle of the thorn-headed 



worm 1 



Review of the literature reporting ex- 

 perimental results 2 



Summary 4 



Pago 

 Tests of anthelmintics 5 



Experimental procedure 5 



Discussion 9 



Conclusions 11 



Literature cited 11, 



INTRODUCTORY NOTE 



A search of the literature reveals few references to critical testsr 

 of anthelmintics for the removal of thorn-headed worms from swine. 

 In spite of the considerable economic importance of this parasite, 

 both in the United States and elsewhere, little attention has appar- 

 ently been paid to treatment. Hall (3) 2 , in 1924, stated that the dis- 

 tribution of the parasite is world-wide, it being found in North 

 America, South America, Europe, Asia, Africa, Australia, and 

 Madagascar. 



The thorn-headed worm attaches to and embeds its head in the 

 wall of the small intestine by means of five rows of well-defined, pro- 

 jecting hooks and causes a local, inflammatory reaction and some 

 necrosis. Apparently because of its tenacious hold on the intestinal 

 wall, it has proved to be resistant to the action of the various an- 

 thelmintics which have been tested for its removal. 



THE LIFE CYCLE OF THE THORN-HEADED WORM 



An effective anthelmintic treatment for the thorn-headed worm i«r 

 the more desirable because the life history of the parasite is such 

 that control by any other method is difficult, if not entirely imprac- 

 ticable. The eggs which pass in the feces of the host may be swal- 



1 The first three sections were written by Willard H. Wright and the fourth, Tests of 

 Anthelmintics, by H. B. Raffensperger. 



8 Reference is made by italic numbers in parentheses to Literature Cited, p. 1L 

 108260°— 30 



