Mosquitoes and Yellow Fever 209 



this connection various writers have called attention to the menace 

 from the Panama Canal. When it is completed, it will allow of 

 direct passage from regions where yellow fever is endemic and this 

 will greatly increase the possibility of its introduction into these places 

 where it is now unknown. The result, with a wholly non-immune 

 population, would be appalling. 



On the other hand, there are places wholly outside of the normal 

 range of Aedes calopus where the disease has raged. Such are New 

 York, Boston, and even Philadelphia, which have suffered notable 

 epidemics. These outbreaks have been due to the introduction of 

 infected mosquitoes during the heat of summer, when they have not 

 only conveyed the disease but have found conditions favorable 

 for their multiplication. Or, uninfected mosquitoes have been thus 

 accidentally brought in and developed in large numbers, needing 

 then only the accidental introduction of cases of the disease to start 

 an epidemic. 



Methods of control of various diseases have been revolutionized 

 by the discovery that they were insect-borne, but in no other case 

 has the change been as radical or the results as spectacular as in the 

 case of yellow fever. The "shot-gun quarantine," the sufferings and 

 horrors, the hopelessness of fighting absolutely blindly have given 

 way to an efficient, clear-cut method of control, based upon the knowl- 

 edge that the disease is carried from man to man solely by the mosqui- 

 to, Aedes calopus. The lines of defense and offense are essentially 

 as follows : 



In the first place, when a case of yellow fever occurs, stringent 

 precautions must be adopted to prevent the infection of mosquitoes 

 and the escape of any already infected. This means that the patient 

 must be removed to a mosquito-proof room, or ward beyond reach of 

 the insects, and that the infected room must be thoroughly fumi- 

 gated at once, to kill the mosquitoes hiding within it. All cracks 

 and openings should be closed with strips of paper and fumigation 

 with burning sulphur or pyrethrum carefully carried out. 



It should be remembered that if the first case noted is that of a 

 resident rather than imported, it means that the mosquito carriers 

 became infected more than two weeks before the case was diagnosed, 

 for as we have seen, the germ must undergo a twelve-day period of 

 development within its insect host. Therefore a careful search must 

 be made for mild cases which, though unrecognized, may serve as 

 foci for the spread of the disease* 



