580 Yellow Fever 



4. The premises where such a case has occurred should be 

 fumigated by burning pyre thrum powder (i pound per 1000 

 cubic feet) to stun the mosquitoes, which fall to the floor and 

 must afterward be swept up and destroyed. 



By these means Major W. C. Gorgas,* without expensive 

 disinfection and without regard for fomites, has virtually 

 exterminated yellow fever from Havana and from the Canal 

 Zone, Panama, where it was for many years endemic. 



A practical point connected with the screens is given in the 

 work of Rosenau, Parker, Francis, and Beyer, | who found that 

 to be effective the screens must have 20 strands or 19 meshes 

 to the inch. If coarser than this the stegomyia mosquitoes 

 can pass through. 



Reed and Carroll { were the first to filter the blood of yellow 

 fever patients and prove that after it had passed through a 

 Berkefeld filter that kept back Staphylococcus aureus, it 

 still remained infective and capable of producing yellow fever 

 in non-immune human beings. 



This subject was further investigated by Rosenau, Parker, 

 Francis and Beyer, who found that the virus was even smaller 

 than the first experiment would suggest, as it not only passed 

 through the Berkefeld filter, but also through the Pasteur- 

 Chamberland filter. The filtrates always remained sterile 

 when added to culture-media. 



The virus has not been artificially cultivated. 



Prophylaxis. Guiteras|| has studied the effect of inten- 

 tionally permitting non-immunes who are to be exposed to the 

 disease to be experimentally infected by being bitten by in- 

 fected mosquitoes, after which they are at once carefully 

 treated. His first conclusion was that "the intentional inoc- 

 ulation gives the patient a better chance of recovery," but the 

 danger of death from the experimental injection was later 

 shown to be so great that it had to be abandoned. 



* International Sanitary Congress held at Havana, Cuba, Feb. 16, 

 1902; Sanitary Department, Havana, series 4. 



f Report of Working Party No. 2, Yellow Fever Institute, Bull. 14, 

 May, 1904. 



| "Am. Med.," Feb. 22, 1902. 



"Bull. No. 14, U.S. Public Health and Marine Hospital Service," 

 Washington, D. C., May, 1904. 



|| "Revista de Medicina Tropical," Havana, Cuba, 1902. 



