274 ILLINOIS STATE ACADEMY OF SCIENCE 



THE RELATION OF ANIMAL DISEASES TO 

 PUBLIC HEALTH 



Thomas G. Hull, Chief, Diagnostic Laboratories, 



Illinois Department of Public Health, 



Springfield 



"Man is his own worst enemy" in the spread of com- 

 municable diseases, but the lower animals are a close 

 second. It is only necessary to cite bubonic plague, a 

 disease of rats, which carried off 25 percent of the 

 world's population not so long ago and which is today 

 costing the United States Government large sums of 

 money in preventive measures. Another instance is 

 sleeping sickness, a disease primarily of animals and 

 transmitted by the tse-tse fly, which makes certain parts 

 of Africa actually uninhabitable for either white man 

 or native. Some prominence has been given this ques- 

 tion lately through the offer of the Germans to give to 

 the world a cure for sleeping sickness in return for cer- 

 tain territory. 



But to get nearer home, take our own domestic cow. 

 Tuberculosis is by far the most serious problem, ranging 

 in extent from 2 to 3 per cent of the cattle in the southern 

 part of Illinois to 50 per cent or more of the animals in 

 the intensive dairying districts of the northern part of 

 the state. The hogs that follow the cows, and the chick- 

 ens that follow the hogs may also become infected with 

 bovine tuberculosis and be incidental sources of danger. 

 The chief source of danger is through milk to children. 

 In surveys made some years ago in several large cities 

 about 10 per cent of milk samples were found infected 

 with tubercle bacilli, and this figure probably holds good 

 today in the average small city of Illinois. Efficient and 

 compulsory pasteurization has eliminated danger in the 

 large cities. AVhile 25 per cent of tubercular children 

 formerly were infected with the bovine type of the dis- 

 ease, recently bone and gland tuberculosis (evidence of 

 the bovine infection) have been rare occurrences in cities 

 like Chicago. Dr. Lorenz on his last visit to this country 

 cried, "Where is your bone tuberculosis'?" 



