250 

 the herd. Cream and butter from a tuberculous cow are 



almost as infectious as the milk. 



The most practicable and positive method of determining 

 the presence or absence of tuberculosis in a herd is the tuber- 

 culin test. Every cow should be tested at least once a year; 

 and in herds where tuberculosis has been found every cow 

 should be tested twice a year. Remember that a physical 

 examination of the cow or a microscopic test of the milk are 

 not as far-reaching or accurate in picking out of the herd 

 every animal that is tuberculous as the tuberculin test. How- 

 ever, these aids to a diagnosis may supplement, or may be u&ed 

 in connection with, the tuberculin test. 



It may be well to state here that tubercle bacilli, from man, 

 cattle, birds and fish, are the game or identical, but slightly 

 modified by the variations in the condition of the different 

 hosts. Yet, under favorable conditions, tubercle bacilli from 

 cattle can be transmitted to man, and the bacilli from man 

 may be transmitted to cattle. Tubercle bacilli from birds 

 and fish cannot readily be transmitted to man or other ani- 

 mals, but such infection may occur because the germ is only 

 slightly modified in fish and birds. 



T^'phoid bacilli have been found in milk. Hart reports 

 fifty epidemics of typhoid fever with 3,500 cases, and Dr. 

 Freeman, of New York, collected records of fifty- three epi- 

 demics with 3,226 cases ; in all of these epidemics the typhoid 

 bacilli were distributed by milk infected with that geim. 

 When typhoid cases appear along a certain milk-wagon route, 

 or when many of the patrons of a certain milk depot contract 

 typhoid fever, the health officers at once search for the source 

 of the infection at the dairy from whence the milk comes. 



The milk is most frequently infected with typhoid bacilli 

 by using infected water to wash the milk cans, bottles, separ- 

 ators, hands, etc. The water in a well or river may become 

 infected by surface drainage. This is very frequently the case 

 when a dairy hand or some one near the dairy has typhoid 

 fever. It is usually a result of careless handling of stools ard 

 urine from a typhoid patient. According to a recent investi- 

 gator,* the urine from a typhoid patient will contain typhoid 



* Central Bl'ttfur Bac, Band XXIII, No. 14, p. 517. 



