200 INFECTIOUS ABORTION IN CATTLE 
where its presence could not be accounted for on the theory that it 
came from an infected animal.* 
The natural channels of infection in dairy cattle seem to be either 
through the genital tract or the digestive tract. Authors are not agreed 
as to which is the more common. Williams considers the genital 
tract the principal, if not the only, channel of infection. He finds, 
however, that calves fed on infected milk abort in their first preg- 
nancy. 
The period of incubation according to Bang is about 10 weeks. 
Morbid anatomy. The investigations and clinical observations 
reported in this country have not ca led attention to any definite 
*The finding of the bacterium of abortion in milk has occasioned considerable alarm 
as to its possible effect upon calves. In their earlier work, M’Fadyean and Stockman 
called attention to the possible “upkeep of the abortion bacillus in the milk of infected 
cows.” Schroeder and Cotton have found it in the milk of a large number of cattle. 
Fabyan and Smith found it in the milk of cows that had aborted... Cotton has pub- 
lished interesting facts on the presence of the organism in the udders of three cows at 
the Bureau of Animal Industry Experiment Station that were not known to have 
aborted. It should be stated, however, that these animals were in a herd in which 
abortion had occurred. 
The resistance of the Bang organism to disinfectants and heat has been studied by 
several. Zwick and Wedemann found that it was killed by a 2.5 per cent. kresol 
solution in 2.5 minutes when a one day old culture was used and in 15 minutes when a 
three day culture was employed and 40 minutes with a seven day culture. They found 
a 3 per cent. solution of carbolic acid, or a 2.5 per cent. dilution of formalin able to 
destroy it in from ten to twenty minutes. Old cultures were more resistant than those 
that were but two days old. Preisz found that it was destroyed by a 1-1000 corrosive 
sublimate solution in 15 seconds. 
Rich found in laboratory tests that one part of corrosive sublimate in 10,000 parts of 
water destroys the organism in from one to three minutes. For stable disinfection, he 
recommends a dilution of 1 to 1,000. He found that a solution of lysol, 1 part in 1,000, 
killed the organism in from three to five minutes. Liquor cresolis compositus was quite 
as effective as the lysol solution. 
Zwick and Wedemann found that a temperature of 55° C. in a water bath would kill 
the organisms in from twenty-five to thirty minutes. A 60° C. temperature destroyed 
them in from ten to fifteen minutes. M’Fadyean and Stockman found that a tem- 
perature of from 55° to 60° C. was fatal in ten minutes. Fabyan found the thermal 
death point to be 59° C. for ten minutes. 
The virulence of the Bang organism varies in a marked degree in different cultures as 
indicated by their effect on pregnant cattle and guinea pigs. The inoculation of preg- 
nant cattle either intravenously or by feeding produces abortion in certain cases after 
a variable length of time. A fibrino-purulent inflammation of the fetal and maternal 
placenta has been reported. A like inflammation has been observed in the stomach 
and intestines of aborted fetuses. 
In-guinea pigs the lesions resemble somewhat closely on microscopic examination 
those produced by the bacterium of tuberculosis not only in their general appearance 
but also in their distribution in the spleen, liver and lymph nodes. They usually appear 
between the third and sixth week, the acute changes extending over a period of ten. 
to twenty weeks after which reparation processes begin. ‘The disease is accompanied 
by fever and tends toward a final recovery although the animal may die from rupture 
of the spleen, emaciation and exhaustion. All the tissues may be attacked with the 
exception of the muscles. Jensen traced the cause of white scours in calves to the 
abortion organism in one case out of 208. 
