BIOLOGY AND HUMAN WELFARE 



393 



(protozoologists), and by physicians highly trained in general 

 medical zoology are behind the scenes in making clear the way to 

 eradicate a disease which, it is estimated, each year costs the United 

 States not less than one hundred million dollars and the British 

 Empire three times that amount. In India alone it is respon- 



DEATHS FROM 

 /MALARIA 



"®§§§PSl, IN L0U/5IANA IN 1915-1919-1920 



I All T»f AMPHEL£S MOSQUIT& 

 ' I CAUSE THESE DtATHS 



I kill ed mny more in previcus 



YEARS AND LVtPlCT TO KILL 

 MORE 111 YEARS TO COHE 



I also cause many thousand asrs 



OF S/OWTSJ AND COST LOUISIANA 

 43001 64,000, 000**- A YEAR 



WHAT ARE YOU GOING TO DO ABOUT Iff 



LOUISIANA 

 STATE BOARD OF HEALTI 



Fig. 247. — Map used in anti-malaria campaign in Louisiana. Each dot 

 represents a death from malaria. 



sible for a death list of more than a million people annually. 

 (Figs. 246, 247.) 



Yellow Fever. Proof that malaria is due to a Protozoon 

 which can only be transmitted to Man by members of a certain 

 genus of Mosquitoes, was largely the work of English, French, and 

 Italian biologists; but the demonstration that another kind of 

 mosquito, Aedes, is responsible for the transmission of the agent 

 which causes yellow fever is due to Reed, Lazear, and other mem- 

 bers of the United States Yellow Fever Commission working in 

 Cuba in 1900. This was followed by the investigations of many 

 biologists, with the result that to-day one may be vaccinated with 

 a weakened virus of yellow fever and probably be rendered immune 

 for several years. 



