Mosquitoes and Yellow Fever 579 



5. Yellow fever can be experimentally produced by the 

 subcutaneous injection of blood taken from the general 

 circulation during the first and second days of the disease. 



6. An attack of yellow fever produced by the bite of a 

 mosquito confers immunity against the subsequent injection 

 of the blood of an individual suffering from the non-experi- 

 mental form of the disease. 



7. The period of incubation in 13 cases of experimental 

 yellow fever has varied from forty -one hours to five days and 

 seventeen hours. 



8. Yellow fever is not conveyed by fomites, and hence 

 disinfection of articles of clothing, bedding, or merchandise, 

 supposedly contaminated by contact with those sick with the 

 disease, is unnecessary. 



9. A house may be said to be infected with yellow fever 

 only when there are present within its walls contaminated 

 mosquitoes capable of conveying the parasite of this disease. 



10. The spread of yellow fever can be most effectually 

 controlled by measures directed to the destruction of mos- 

 quitoes and the protection of the sick against the bites of 

 these insects. 



11. While the mode of propagation of yellow fever has 

 now been definitely determined, the specific cause of the 

 disease remains to be discovered. 



The probability that Bacillus icteroides is the specific 

 cause and is transmitted by the mosquito is so slight that it 

 need scarcely be considered. All analogy points to the 

 organism being an animal parasite similar to that of malarial 

 fever. 



With this positive information before us, the prophylaxis 

 of yellow fever and the prevention of epidemics of the disease 

 where sporadic cases occur becomes very simple and may be 

 expressed in the following rules: 



1. Whenever yellow fever is likely to occur, the breeding 

 places of mosquitoes should be destroyed by drainage. Cis- 

 terns and other necessary collections of standing water should 

 be covered or secured. 



2. Houses should have the windows and doors screened 

 and the inhabitants should use bed nets. 



3. So soon as a case of fever appears it should be removed in 

 a mosquito-proof ambulance to a mosquito-proof apartment 

 in a well-screened hospital ward and kept there until con- 

 valescent. 



