15 



Section C 



3. That the diminution of the number of infected vessels reaching 

 United States ports is due mainly to the sanitary measures for avoiding 

 exposure to infection in the foreign port, and to the substitution of steam 

 for sailing vessels. To some degree the falling off of the vessels from 

 Brazilian ports is also a factor. 



4. That a case of yellow fever develdping aboard a vessel plying 

 between southern ports of the United States and the tropics will prob- 

 ably infect the. vessel so that other cases can, if time be given, be con- 

 tracted aboard her. 



5. Such vessels, however, if short-trip vessels, not more than ten or 

 twelve days en route after the occurrence of the case of yellow fever, 

 will in general be disinfected at southern quarantine stations before any 

 other cases have been contracted aboard, although harboring infected 

 mosquitoes. 



6. That a case of yellow fever so occurring aboard a vessel from a 

 northern port of the United States would be able to infect her or not 

 according to whether she had acquired the mosquitoes stegomyia fas. 

 in the tropical port. 



7. It is, in general, then necessary to disinfect all vessels running 

 between southern ports of the United States arid tropical ports if a case 

 of yellow fever occurs aboard, no matter where it be contracted ; while 

 vessels running between northern ports and the tropics may, through 

 precautions in tropical harbors, have no stegomyia aboard and are thus 

 not infectable by cases of yellow fever occurring aboard. 



8. Some vessels giving no history of yellow fever in port, en route, 

 or on arrival — even when many days en route — are nevertheless infected 

 and communicate the yellow fever to those who go aboard, vide Nos. 

 IV, V, VI, VII. Note, also, the first case aboard the Avon, No. Ill, was 

 thirty- eight days out from Eio de Janeiro. This is probably due to the 

 infection (infected mosquitoes) in parts of the vessels unfrequented by 

 the crew while en route, or to the crew being all immune to yellow fever. 



