SPOROZOA 783 



in the long run to begin in the center of the settlement, with perma- 

 nent improvements, working outwards as money becomes available, 

 and not to depend on oiling except as a temporary measure. 



3. The infection is kept alive in a community by human carriers, 

 and these are especially common among natives and the poor and 

 ignorant. Newcomers should not live within five hundred yards of the 

 dwellings of these classes, as infected anophelines can easily travel 

 shorter distances. Only when it is possible to protect the natives also 

 by these measures is it safe to live among them ; and that this is pos- 

 sible has been shown many times, particularly in Panama. 



4. The proper treatment and cure of all cases will not only pre- 

 vent relapses and the carrier state (malarial cachexia), but is one of 

 the most important means of exterminating the disease, since every 

 neglected case becomes a focus for new mosquito and in consequence 

 new human infections. It is just as important a part of the preven- 

 tion of the disease as any other single measure. 



5. Quinine prophylaxis is an unsatisfactory measure which must 

 be used by travelers, explorers and troops. There is no method of 

 using quinine which will entirely prevent malaria when the chances 

 for infection are many; the following methods have all been used: (1) 

 The so-called gram prophylaxis, in which one gram of quinine is taken 

 intermittently every tenth day as the minimum to every fourth day 

 as the maximum. The gram may be taken in a single dose at bed-time, 

 or in four divided doses during the day-time. (2) The double gram 

 prophylaxis, in which the dose is taken on two successive days, as, for 

 example, on the tenth and eleventh, or on the fifth and sixth. (3) 

 The half gram prophylaxis, as proposed by A. Plehn, was 0.5 gram- 

 every fifth day; experience has shown that it is of little value. (4) 

 A daily dose of 0.4 to 0.8 gram gives better results than any other 

 method, since the patient suffers less from cinchonism than when 

 larger doses are taken intermittently, and takes his quinine more 

 faithfully. The size of the dose depends on the form of fever pres- 

 ent and the number of chances for infection; 0.4 gram will often 

 protect against tertian and quartan, while even 0.8 may fail to pre- 

 vent aestivo-autumnal. Latent infections and relapses among "prophy- 

 lacticers" are common and black water fever is not an infre- 

 quent sequel. 



6. Personal prophylaxis by means of head nets, gloves, suitable 

 clothing, and the use of essential oils, such as citronella, on exposed 

 parts of the body, is helpful in emergencies. 



