SPOROZOA 1125 



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 present and the number of chances for infection; 

 0.4 gram will often protect against tertian and quartan, while even 

 0.8 may fail to prevent aestivo-autumnal. Latent infections and 

 relapses among "prophylacticers" are common and black water 

 fever is not an infrequent sequel. 



It is well to remember that quinine is rapidly absorbed from 

 the intestinal tract and also as rapidly excreted, and that so far 

 as possible the doses should be properly timed. 



It is probable that quinine is already in the blood within half 

 an hour of the time it is taken, and that the whole dose is absorbed 

 within six hours and that most of it has already been excreted in 

 the same period. To provide quinine in the blood in sufficient con- 

 centration to be effective in killing the sporozoites injected by the 

 mosquito, it is most reasonable to take one dose of five grains an 

 hour before sunset, and a second dose, if one is compelled to be 

 out, just before midnight. Ten grains taken in this way will provide 

 against infection at dusk and at dawn, the two principal periods 

 during which the anophelines bite, better than one dose at bed time, 

 of the same size. 



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. 



7. The protection of human beings by means of animal barriers 

 has been recommended by several writers. The subject has been 



