HEALTH AND DISEASE OF POULTRY 579 



When the disease exists in a flock of fowls there are usually many in 

 the early stages that do not betray their conditions by appearance or 

 behavior. This insidious mode of development is an important 

 characteristic of tuberculosis and one that frequently blinds peo- 

 ple to its seriousness. There is no apparent way of recognizing all 

 the tuberculous fowls in a flock so that they may be removed. 

 Therefore, all the individuals in an infected flock must be regarded 

 as dangerous to those free from the disease, and must be kept sepa- 

 rated from them. To counterbalance this difficulty the problem of 

 controlling tuberculosis in fowls has some encouraging features. 

 The useful life of the hen is generally regarded as ended at three 

 years of age. This fact obviates the necessity for the quarantine of 

 infected individuals for many years, as is done with cattle. The 

 further spread of the disease through a flock where it already exists 

 may be impeded by sanitary measures. Fowls suspected of having 

 tuberculosis should be slaughtered promptly. The roosting-houses 

 should be cleaned and disinfected as often as practicable. It should 

 be remembered that cases which can not be detected are constantly 

 spreading the germs of the disease about the houses, and in conse- 

 quence the effect of one spraying with a disinfectant is of short dura- 

 tion. There are upon the market several disinfectants that are suit- 

 able for the purpose. 



There is good reason to believe that young stock may be kept 

 free from tuberculosis by completely isolating them from hens 

 among which the disease exists, or from land recently occupied by 

 such fowls. The conditions under which the poultry business is 

 carried on do not seem to offer serious objection to such practice. 

 In the establishments where the fowls are kept in inclosures this 

 condition may be easily maintained. Upon the larger ranches 

 where the fowls are not restrained, and roam at will in the vicinity 

 of their respective colonies, the quarantine may not be so strictly 

 enforced. Much danger may be avoided bv locating the colonies of 

 pullets as far as possible from the old stock, or from land recently 

 contaminated by them. The complete isolation of the young from 

 contact with the diseased is a precaution unquestionably successful 

 in preventing the spread of tuberculosis in man and cattle; and 

 there seems to be no reason why the principle should fail in the case 

 of poultry. The experiment is being tried with pullets hatched dur- 

 ing the present season. 



Transfer of laying hens appears to be an important cause of 

 the spread of the disease to ranches where it has not hitherto existed. 

 On sanitary grounds the purchase of grown stock is condemned as 

 dangerous; for there is a strong probability that the purchaser will 

 receive fowls from a flock that has had a bad record of deaths from 

 tuberculosis or other causes. Enough examples of such cases have 

 been observed to warrant wording an emphatic warning. Those 

 embarking in the poultry business should aim to raise their own hens. 



Relation to Tuberculosis in Man and Cattle. The subject of 

 the relationship between tuberculosis in man or cattle and the dis- 

 ease in fowls is full of interest. Tuberculosis in cattle is prevalent 



