1122 PATHOGENIC PROTOZOA 



Epidemiology. Since malaria is conveyed solely by the bite of 

 an infected anopheline, the epidemiology is comparatively simple. 

 In practice, nevertheless, the prevention of the disease is extremely 

 difficult; but it is the same for all forms of malaria. It must be 

 attacked from all possible angles and the following are the main 

 points to be observed : 



1. Screened houses afford, perhaps, the simplest form of protec- 

 tion, and in beginning work in a new, badly infected place, should 

 be the first thing provided, since they afford a place of security in 

 an otherwise dangerous area, where the workers may take refuge 

 until the situation is under control. This method alone has given 

 magnificent results in Italy (Celli) since it was first used experi- 

 mentally by Sambon and Low in the Roman Campagna. The screens, 

 to be durable, must be of bronze and not iron, and of a fine mesh 

 (20 strands to the inch), and should .be placed, not on windows and 

 doors, but on the outside of porches and balconies ; doorways should 

 have screened vestibules. 



In default of metallic house screens, bed nets may be used, 

 although they are not very satisfactory, since one must retire at 

 dusk to be protected. In default of both screens and bed nets, 

 something may be accomplished, temporarily, by daily mosquito 

 catching, and in Panama the method has given remarkable results. 

 A native, armed with a small acetylene lantern and a few catching 

 bottles, soon becomes expert, arid can capture each day all the 

 mosquitoes in a number of dwellings. In this way very few anophe- 

 lines escape capture long enough to become infective for man. 

 Chloroform catching bottles are easily prepared by packing a half 

 ounce of small rubber bands, cut up finely, into the bottom, and 

 pouring in as much chloroform as the rubber will absorb and 

 covering it over with dry blotting paper. The wide-mouthed catch- 

 ing bottle is uncorked and inverted over the resting mosquito, which 

 is killed by the chloroform. A convenient trap bottle has been 

 described by La Prince. Below the cork is placed a funnel trap, 

 making it possible to pass from one spot to another without waiting 

 for the chloroform to act upon the mosquito. 



2. The second measure is the prevention of mosquito breeding; 

 this is a large but not a hopeless undertaking, if carried out intel- 

 ligently. In the first place, it is to be remembered that compara- 

 tively few mosquitoes are disease carriers, and that measures need 

 be directed against them only. It was first shown, for example, by 



