74 ANNUAL r.EPORTS OF DEPAETMEXT OF x\GEICULTUEE. 



By contributing to the arrival of the stock in the best possible condi- 

 tion, the revised regulations are a factor leading to a continuance of 

 our export trade in li\e stock. During the year numerous shipments 

 of both cattle and swine were made to South American points under 

 export certificates issued by the bureau. 



PROGRESS IN DISEASE CONTROL. 



The long and anxious cam[)aign which the bureau has been Avaging 

 against animal diseases brought encouraging results during the last 

 year. From a scientific jioint of view, victory over most of these 

 maladies is in sight, and in a number of cases eradication is nearly 

 complete. (See accompanying charts.) 



Cattle scabies, which in 1906 Avas prevalent in nearly one-half of 

 the United States, noAv appears only as outbreaks in limited areas. 

 These outbreaks are being suppressed. 



Ei-adication of sheep scabies, Avhich in lOOG existed in more than 

 one-half of the land area of the country, is now about nine-tenths 

 complete. 



The cattle tick Avhich causes Texas fever has had its domain re- 

 duced from more than 700,000 square miles in 190() to less than 

 300,000 square miles in 1918. Progress has been continuous year 

 after year. 



Hog cholera presents a somewhat different problem, as the natuie 

 of the disease makes the campaign of a sporadic character. But the 

 use of antihog-cholera serum, especiall}^ in connection witli virus, is 

 a definite means of prcAenting serious outbreaks. 



Eecent investigations Iuiac sIioavh that the common intestinal 

 roundworm of the pig is not only injurious as an intestinal parasite 

 but that during an early stage of its development, Avhile still micro- 

 sco})ic in size, it invades the lungs and may give rise to serious 

 troubles. Furthermore, pigs that survive this invasion of the lunas 

 may iie\er fully recover, but fail to grow properly, and become un- 

 profitable runts. It is believed that much of the damage caused i)y 

 the intestinal roundAvorm can be avoided by simple sanitary ])re- 

 cautions, the practical application of Avhich is noAv l)eing tested. The 

 problem of so called "mixed infection"' is also under investigation, 

 with the ^'icAA of determining more definitely its relation to hog 

 cholera and the proper measures of control. 



The United States has remained free from foot-and-mouth dis- 

 ease, and the bureau continues to exercise vigilance against its possible 

 introduction. Serious outbreaks in foreign countries have been 

 cio.sely studied, and bureau inspectors have given special attention 

 to cargoes of live-stock products from such countries. inq)ortations 

 of the animals themselves not being i)ermitted. 



A questionnaire inquiry made among stockmen and State oflicials 

 indicates an almost universal support of the method Avhich the bureau 

 employed successfully in stamping out past outbreaks of foot-and- 

 mouth (hsease by slaughter of the animals alTected. 



Eradication of tuberculosis has i)rogressed as fast as the work 

 covild be handled by the Aeterinary force employed; in fact, there 

 has l)een a Avaiting list of herds to be tested. Under present authority 

 from Congress only one-third of the appropiation for tuberculosis- 



