PREVENTION OF MALARIA 173 
In order to combat malaria he, at Stephansort, where malaria was rife, sought 
out all cases of malaria and persons with parasites in their blood, and treated them 
systematically with quinine. 
By this means he was able to greatly reduce malaria in the on-coming season 
at Stephansort, although the climatic conditions were particularly favourable for the 
development of the disease. Koch, in his fifth report to the German Imperial 
Health Bureau, sums up as follows : ' The results of our experiment, which has 
lasted nearly six months, have been so uniform and unequivocal that they cannot be 
regarded as accidental. We may assume that it is directly owing to the measures 
we have adopted that malaria here has in a comparatively short time almost 
disappeared.' 
In a community then which can be kept under observation and systematically 
treated with quinine, malaria can be combated very effectively. In many parts of 
the world this method very probably will be the way in which the desired diminution 
of malaria will be brought about. In Africa, however, such a method is quite 
inapplicable, and it would be quite impossible to carry it out under existing 
conditions, even in the most limited way. 
A second method of getting rid of the source of infection is, however, 
peculiarly adapted to Africa. 
2 The method first recommended by the Malaria Commission, and later 
strongly advocated by the expedition of the Liverpool School to Nigeria, viz., 
segregation of Europeans from Natives. 
This method is a corollary of the discovery that native children in Africa 
practically all contain the malaria parasite and are the source from which Europeans 
derive malaria. 
Koch shewed in New Guinea that in most places infection was very prevalent 
in native children, so much so that in some villages 100 per cent, of those examined 
contained parasites. He also shewed that as the children increased in age immunity 
was produced, so that in the case of adults a marked immunity was present and 
malarial infection was absent. 
The Malaria Commission shewed independently that a condition of universal 
infection existed among the children of tropical Africa, associated with an immunity 
of the adults. This infection in children had many remarkable characteristics. The 
children were in apparent health, but often contained large numbers of parasites, and 
a small proportion only of the children failed to shew some degree of infection. 
Not only were the children in every village and every hut infected, but anopheles 
were found which, from feeding on the children, had become infected. 
It became evident that European malaria in Africa was but a mere indication 
of an enormous degree of infection throughout the whole of the malarious regions 
of Africa ; and that the clue to the prevention- of malaria among Europeans in Africa 
H 
