YEAR 



250 SOO 750 1000 IZ50 ISOO 



1873 



1874 



1879 



188B 



1884 



1885 



1889 



1893 



282 THE RELATIONS OF ANIMALS TO DISEASE 



could not be spread. The accompanying illustration shows the 

 result of this discovery for the city of Havana. For years Havana 

 was considered one of the pest spots of the West Indies. Visitors 

 shunned this port and commerce was much affected by the con- 

 stant menace of yellow fever. At the 

 time of the American occupation after 

 the war with Spain, the experiments 

 referred to above were undertaken. 

 The city was cleaned up, proper sani- 

 tation introduced, screens placed in 

 most buildings, and the breeding places 

 of the mosquitoes were so nearly de- 

 stroyed that the city was practically free 

 from mosquitoes. The result, so far as 

 yellow fever was concerned, was star- 

 tling, as you can see by reference to the 

 chart. It was eighteen years after the 

 discovery of the carrier of yellow fever 

 that its cause was discovered by Dr. 

 Noguchi (no'goo-cHe) of the Rockefeller 

 Institute. This is a one-celled organ- 

 ism — a spirochcete (spi-r6-ke'te) — so 

 small as to escape detection except 

 under the most powerful microscope. 

 Dr. Noguchi has prepared a vaccine 

 and a serum, both of which have been 

 used with great success in South 

 America under the auspices of the 

 Rockefeller Institute.^ 

 Other Protozoan Diseases. — Many other diseases of man are 

 probably caused by parasitic protozoa. Dysentery of one kind 

 appears to be caused by the presence of an amoeba-like animal 

 {entamoeha) in the digestive tract. Rabies, possibly smallpox, 

 and other diseases are caused by protozoa. Relapsing fever and 

 the dread disease syphilis are caused by spirochsetes, organisms 

 which look like the spirillum. 



1894 



1895 



1897 



1899 



1905 



1906 



1907 



1910 



1/8 Carrier of yellow fever discovered 



NONE 



NONE 



1 24 First Cuban rule 



NONE 



NONE 



Notice the difference in the 

 number of yearly deaths from 

 yellow fever before and after the 

 American occupation of Havana. 



^ See Eighth Annual Report of the International Health Board of the Rocke- 

 feUer Institute, 1921. 



