SCIENCE AND INDUSTRY. 
An important point demanding careful inquiry is as to the time of infection. 
It is generally considered that the discharge from a recently aborted cow is the 
commonest source of infection. Such material may contaminate bedding mate- 
rial, or hay for fodder, or, out in the open, the grass, and the material so 
infected is eaten by other susceptible animals, which themselves become infected. 
If this be true, then care of the newly aborted cow, including isolation, irriga- 
tion. of the genital canal with an antiseptic, and proper disposal of all discharges 
and soiled fodder and litter, are the obvious preventive measures. 
But with the discovery that the abortion bacillus is voided in the milk of a 
large number of cows comes another possibility which has serious consequences. 
W. L. Williams, of New York State Veterinary College* has suggested that the 
young calf suckling may become infected by means of milk containing the 
bacillus, retain. the infection without symptoms until pregnant, and then in @ 
number of cases abort, or, in any case, continue to spread the infection. This 
possibility opens up further chances of infection, for it may often happen (on 
this hypothesis) that a clean unaffected herd producing milk which is sent to 
the butter factory, and feeding calves on the returned separated milk, will 
become infected by means of milk from affected herds, which also supply the 
same butter factory. 
The return by butter factories of unsterilized and unpasteurized separated 
milk—the mixed milk of several cows and several herds—is a potent source of 
many infections, notably tuberculosis, and, on Williams’ hypothesis, contagious 
abortion. This theory of infection has not been proved. Jt is a matter on 
which research work is being done, and the results are important. Meantime 
Williams advises only boiled milk for the feeding of calves, a quite effective 
method of prevention. 
To sum up on this point, it may be stated that there are various possibilities 
of infection, instead of only one method as was formerly taught, and with 
these added possibilities the chances of infection are greatly multiplied. Special 
preventive measures are indicated, and special research is proceeding in many 
places to determine the truth on these matters, Such research, however, takes 
a long time, and, moreover, it is expensive, since it deals with cattle expensive 
to purchase and costly to keep. 
One other question of considerable interest may be discussed briefly, namely, 
the possibility of some form of vaccination or inoculation to render animals _ 
immune to the disease. A point of importance in this connexion is that infec- 
tion with contagious abortion produces no systemic reaction, as a rule, i.e., there 
is no rise of temperature or other febrile symptoms. Again, an animal may 
remain infected and continue to void the causal organism, the abortion bacillus, 
in the milk for years. Thus, under natural circumstances, the immunity 
developed as a result of natural infection is of a very low order. It is true 
that most cows which abort do so only once, a small number may abort twice, 
and a very small percentage three times. It is also true that the disease in a 
herd tends to lessen and apparently die down in a few years if no new stock * 
is introduced from outside. But the infection is still there, as can be proved 
by bringing in a few pregnant uninfected heifers. 
This low degree of immunity set up under natural conditions may be the 
explanation why artificial immunization is not yet satisfactory. Two methods 
have been tried on a large scale. The first is by the use of killed cultures. 
Just as in the successful vaccination against typhoid fever in man, so in this 
*Report of New York State Veterinary College, Connell University, 19114-5. 
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