436 HUMAN BIOLOGY 



Malaria is probably the commonest and most disabling 

 disease in the tropics; in India alone more than four million 

 victims apply annually for treatment on this account. The 

 mortality and economic loss thus produced are enormous and 

 now'^fortunately are preventable. The deteriorating effect on 

 national health and morale is very real, and W. H. S. Jones 

 has brought together evidence to show that the decadence of 

 Magna Graecia in 400 B.C. was largely due to the prevalence 

 of malaria. Cinchona or Jesuit's bark, which contains 

 quinine, owes its name to its successful use in the treatment 

 of the Countess of Cinchon in 1638, and is said to have been 

 accidentally discovered by the natives of South America 

 before the Spanish invasion of 1 630-1 640. Writing in 1897 

 Sir William Osier (1849-1919) regarded its introduction as 

 not only one of the greatest events in medical history but 

 as one of the great factors in the civiHzation of the world. 

 It did much to cure the disease and to mitigate the evils of 

 the disease by destroying the parasite when it has gained 

 entrance to the circulation, and small doses may protect 

 persons from becoming affected. In 1880 a French military 

 surgeon C. L. A. Laveran (1845- 1922), ^^st observed the 

 malarial parasite; in 1894 Patrick Manson (1844- 1922) 

 applied to malaria the hypothesis, based on his previous 

 discovery that mosquitoes conveyed the filarial parasite to 

 man, and in 1898 Ronald Ross proved that mosquitoes 

 conveyed the malarial parasite to man. It thus became 

 evident that mosquito-borne diseases could be prevented 

 by making it impossible for mosquitoes to bite human beings; 

 this can be done by keeping the mosquitoes off by netting 

 and screening, but the most satisfactory means is the 

 complete irradication of mosquitoes. Anti-malarial cam- 

 paigns for the destruction of mosquitoes by various methods 

 have in many places, as was notably shown in Havana and 

 the Panama Canal area under General W. C. Gorgas' (1854- 

 1920) direction, entirely changed the sanitary conditions in 

 tropical regions previously deserving the epithet of "the 

 white man's grave." As already mentioned, yellow fever, 

 which formerly levied a terrible toll of human life, is also 

 conveyed to man by the bites of a mosquito, Aedes aegypti 

 or Stegomyia Jasciata, and has now been almost completely 



