II44 



THE MALARIAL FEVERS 



Africa. — ^The worst malarial region in the world is probably the 

 West Coast of Africa, from Senegal to the Congo, but the whole of 

 Africa, except portions of Cape Colony, is malarial. 



Asia. — -Malaria is widespread throughout Asia, being very 

 marked in certain districts of India, especially the swampy land at 

 the foot of the Himalayas, in Ceylon, and Borneo; while Arabia, 

 Syria, the Straits, Siam, and China are also malarial. Little is 

 known about Siberia. 



Australasia and Polynesia.' — Malaria occurs in the north of 

 Western Australia, the Northern Territory, North Queensland, 

 Torres Straits Islands, New Guinea, Finschaf en, the Solomon Islands, 

 and the Bismarck Archipelago. 



America. — Malaria exists in Central America, the West Indies, 

 with the exception of Barbados, the coast of the Mexican Gulf, the 

 north of South America, including British Guiana, and the north 

 of Brazil as far as Rio de Janeiro. Paraguay and Bolivia are 

 infected, as are Peru and Chili, but the south part of South 

 America is less infected. Many places in the United States are 

 malarial, but Canada is not markedly infected, except about the 

 northern shore of Lake Ontario, while Greenland is supposed to 

 be free. 



Europe. — -Great Britain and Norway are practically free, but 

 most of the other countries have endemic foci, particularly Russia, 

 Italy, Serbia, Greece, Turkey, and Austria-Hungary. 



In France malaria exists in the south and west ; in Switzerland in 

 the canton of Tessin; in Germany along the course of the Rhine, 

 and in the lowlands watered by the tributaries of the Danube. 

 Sweden has also some endemic spots. 



Apart, however, from mere geographical distribution, it will be 

 obvious that the necessary conditions for malarial propagation are 

 best supplied in the tropics, especially near the Equator, where 

 there is generally a considerable amount of atmospheric moisture 

 and rain as well as heat. 



The wet season has also a great influence, supplying the necessary - 

 moisture which at other times may be lacking. The effect of alti- 

 tude has already been mentioned. 



Pathology. — In malaria the body is invaded by protozoal para- 

 sites, which grow and increase at the expense of the red cells of the 

 blood, and in doing so manufacture toxins, of which we know two 

 — viz., a pyrogenetic toxin and a hsemolysin. 



Red blood cells are found in the whole of the circulatory organs, 

 but are generally contained in arteries, veins, and capillaries. In 

 two places, however — viz. , the spleen and bone-marrow — they come 

 intimately into relationship with the parenchyma cells. Whatever 

 function the spleen may in future be found to possess as regards 

 the malarial parasites, it probably acts as a purifier to the blood 

 which passes through it. Perhaps the bone-marrow assists in such 

 a function. 



Parasites contained in red cells should, therefore, be able to pa 



