PREVENTIVE MEDICINE 287 



CONTAGIOUS BOVINE PLEURO-PNEUMONIA. 



Contagious bovine pleuro-pneumonia (lung plague) is an 

 acute or sub-acute, though frequently somewhat insidious, disease 

 affecting only bovine animals and caused by an exceedingly minute 

 organism discovered by Nocard and Roux in 1898, and which can 

 only be seen under a magnification of about 2000 diameters. The 

 disease is characterised by lung lesions of a peculiar type and by a 

 fibrinous exudative pleurisy, though the latter lesions are secondary 

 to the pulmonary involvement and may not always be present. 



Pleuro-Pneumonia was at one time a very widespread disease 

 in the United Kingdom and abroad. It was first introduced, it 

 is thought from Holland, about 1840 and its very considerable 

 ravages may be gathered from the statement that in 1873 there 

 were 2711 outbreaks involving 8817 animals, in 1874 3262 outbreaks 

 involving 9225 animals, and in 1877 2007 outbreaks involving 6683 

 animals. During the 25 years ending 1894 103,000 animals died or 

 were slaughtered in the United Kingdom as the result of the 

 disease.* In 1873 slaughter of diseased animals was first made 

 compulsory, but until 1888 for certain reasons little real progress 

 was made in the extermination of the disease. In 1888, however, 

 the principle of compulsory slaughter of affected animals and all 

 incontacts was put into practice, the result being that by 1897 the 

 disease had been stamped out of country districts and was only 

 present in the east end of London. The disease has been non- 

 existent in the British Isles since 1899. 



The causal organism being obligatory, contagion can only spread 

 from animal to animal. The method of infection is by inhalation 

 of infected particles contained in the expired air of diseased 

 subjects, and transmission can thus readily take place in animals 

 which are stalled close together. The period of incubation is some- 

 what lengthy and is generally considered to be about 6 weeks. A 

 rise of temperature occurs earlier than this however, and Nocard 

 and Roux placed the period of incubation after inhalation at 12 to 

 16 days. The virus can remain alive for a certain time outside 

 the body, e.g., Germont and Loir found that the virus kept in glass 

 tubes in the dark and at laboratory temperature could retain its 

 activity for 15 to 20 days. 



PREVENTIVE MEASURES. Outbreaks in the British Isles would 

 always be dealt with by ruthless stamping out methods. All 

 affected animals should be slaughtered, together with any which 

 * Report, C.V.O., Bd. of Agric., 1895. 



