MALAEIA AND ALTITUDE 235 



" Asia. — India, Ceylon, portions of China and Arabia, and the Islands of the 

 Malay Archipelago are infected with the malarial fevers. This is also true of 

 Asia Minor and the valleys of almost all the great rivers, such as the Indus and 

 Ganges. In Japan the benign infections are common, and even upon the lofty 

 table lands near the Himalayas malarial infections are often met with. The 

 Philippine Islands, until very recently considered as comparatively free from 

 malarial diseases, have been proved to be badly infected, a large percentage of 

 our soldiers returning from there showing infection with the tertian and aestivo- 

 autumnal parasites. 



"Africa. — In Africa are some of the most dangerous lurking places of 

 malarial infections, the worst areas being those along the west coast and the 

 Senegal, Congo, and Niger Rivers, as well as the regions around the great lakes 

 and the jungles, and lake shores of Abyssinia. Madagascar, Reunion, and 

 Mauritius Islands present the pernicious varieties of the disease. Around 

 Delagoa Bay and along the east coast of Africa, aestivo-autumnal fever is prev- 

 alent. Lower Eg}'pt, the Soudan, the Mle delta, Tripoli, Tunis and Algeria, 

 all harbor these infections." 



Regarding the vertical distribution of malaria it may be said in a general way 

 that malaria decreases with the increased altitude above sea level. The govern- 

 ing factors are, on the one hand, the unfavorable effect of low temperatures on 

 the development of the malarial organisms, on the other hand, the absence in 

 many mountainous regions of conditions upon which the abundance of Anoph- 

 eles depends. iSTevertheless malaria does occur at considerable altitudes in 

 various parts of the world, apparently going highest in the Andes of South 

 America. According to Treutlein, at La Paz, Bolivia, it reaches an altitude of 

 2564 meters. This author states that while endemic malaria, on account of the 

 conditions, unfavorable to mosquitoes, does not occur at La Paz it exists on the 

 plain of Potopoto, 100 meters lower, where Anopheles breed in some numbers. 

 Ziemann gives the following summary of the occurrence of malaria at high 

 altitudes : 



" While, for example, in Ceylon malaria no longer occurs at 500 meters above 

 sea level, the writer still found malaria in Cameroon and also in the Manenguba 

 mountains at about 900 meters altitude ; however no longer from 1200 meters 

 on in the grass land, and the distribution of malaria and of anophelines seemed 

 to agree pretty closely. Steuber still found malaria in German East-Africa at 

 Lake Nyassa at an elevation of 1560 meters. In the mountainous regions of 

 Usambara the conditions appeared to be similar to those of Cameroon in that 

 malaria there still occurred at 800 meters altitude. In the Himalaya mountains 

 it is said that malaria is still found at a height of 2000 meters, in the Andes of 

 Peru even to 2500 meters, in the high lands of Persia, on the other hand, only to 

 1500 meters. In the German mountains malaria rises to 400-500 meters, in 

 Italy to 600-1000 meters. Recently Grassi even found there an endemic malarial 

 focus, in the vicinity of Colico, at an altitude 2500 meters. In malarial regions 

 comparatively slight elevations above the malaria-infected plain are often 

 sheltered, which one can easily explain, with our present knowledge, by the 

 relatively small height of the flight of anophelines. Therefore the inhabitants 

 of malarial regions always withdrew by preference to the surrounding hills. It 

 is known that the shepherds of the Campagna about Rome passed the nights on 

 scaffoldings which were several meters above the ground." 



Edmond Sergent states that in Algeria, while Anopheles abound at all times 



in altitudes of from 1600 to 1800 meters, malaria occurs in those altitudes only 



