684 



TWENTY-THIRD ANNUAL YEAR BOOK— PART IX 



TABLE NO. 6— Continued 

 Comparative table showing number of swine lost by cholera in Iowa in 

 1922, 1921, 1920, 1919, 1918, 1917, 1916, 1915 and 1913, by counties. 



♦Partly estimated 



Hog cholera decreased in 1922 in spite of the increase in hogs. De- 

 creases were largest in the northwest counties where hogs are most 

 numerous and where rainfall was least; and the largest increases appear 

 to be in sections where excessive rains caused overflows that carried the 

 disease from farm to farm. Vaccination campaigns no doubt had much 

 to do with the general decrease in losses from this disease. 



