14 



be exterminated from any city, but that it is not too much to expect 

 that ocean carriers can be freed from rodents and kept so, which 

 action would confine plague within continental boundaries. 



Epidemiological studies made of plague since the adoption of the 

 International Sanitary Convention of Paris and the International 

 Sanitary Convention of Washington have proven that the rat and 

 its parasite, the flea, are the agents of transmission of the disease. 

 In other words, where rats go plague will go. I believe, there- 

 fore, that in order to stop the further progress of plague, radical 

 measures should be adopted, and in a communication of February 

 26, 1909, addressed to the Secretary of State, I suggested the 

 advisability of submitting the question of a systematic destruction of 

 rodents aboard ship to an international sanitary conference, with the 

 view to the adoption of an international sanitary regulation on the 

 subject. The adoption of such a regulation would undoubtedly lessen 

 quarantine restrictions, prevent the destruction of cargo by rodents, 

 and obviate the danger of the further spread of plague. 



Until ships are freed from rats, each country must take all necessary 

 precautions, consistent with international agreements, to destroy 

 rats; and the sanitary authorities of infected localities must, at great 

 expense, determine the extent of infection among' rodents, with the 

 view to its elimination. This problem when it presents itself in a 

 community is of great magnitude, and those responsible for its 

 solution should be familiar with all its phases. 



It is with the view to supplying the necessary information in one 

 treatise that this publication is issued. In its preparation the bureau 

 has had the cooperation of the Department of Agriculture and 

 acknowledgements are due, and here made to, the officers of that 

 department for their hearty cooperation in contributing some of the 

 chapters which follow. 



