414 CONTAGIOUS PLEURO-PNEUMONIA IN CATTLE 
No case of this disease has occurred in the state of [linois since December 29, 1887, 
a period of more than four years and eight months. 
No case has occurred in the state of Pennsylvania since September 29, 1888, a period 
of four years within a few days. 
No case has occurred in the state of Maryland since September 18, 1889, a period of 
three years. 
No case has occurred in the state of New York since April 30, 1891, a period of more 
than one year and four months. 
No case has occurred in the state of New Jersey since March 25, 1892, a period of six 
months, and no case has occurred in any other portion of the United States within the 
past five years. 
I do therefore hereby officially declare that the United States is free from the disease 
known as contagious pleuro-pneumonia. 
J. M. RUSK, Secretary. 
Done at the City of Washington, D. C., this 26th day of September, A.D., 1892. 
The time required for its eradication was about five years and the 
total expenditure was a little over $1,500,000. 
Etiology. All attempts to discover the etiology of contagious 
pleuro-pneumonia failed until 1898 when Nocard and Roux succeeded 
in obtaining a very feeble growth of an exceedingly minute organism 
in bouillon, containing cow or rabbit serum in proportion of one part 
serum to 25 parts bouillon, when cultivated in collodion sacs within 
the abdominal cavity of rabbits. The rabbits that received the 
inoculated capsules became emaciated, and some of them died. 
Those receiving the uninoculated capsules remained well. With the 
cultures obtained in the collodion sacs the disease was produced in 
cattle. The virus passed through a Berkefeld filter and Chamberland 
F-candle but it was held back by a Chamberland filter B. Under a 
magnification of 1500 diameters and strong light the “bodies” appear 
as minute refracting dots. They are said to appear in several shapes, 
some of which appeared to be branched. The virus is present in the 
affected lung tissue, pleural exudate, lymph glands, bronchial secre- 
tions and nasal discharges. The virus is transmitted by direct con- 
tact. Stables in which diseased animals are kept remain infectious 
for a long time. Affected animals transmit the disease during all 
stages but more surely during the period of acute symptoms. Recov- 
ered animals are reported by Walley to transmit the disease for 15 
months and Minette traced outbreaks in herds of cattle introduced 
two and three years previously. The virus is supposed to enter the 
body through the respiratory tract and develops first in the lymph 
spaces of the interlobular tissue. 
