MEDICINE, RECENT ADVANCES IN. 



349 



sufferers. The equipment of the camp included 

 two frame buildings, one of which, known as the 

 " infected-mosquito building," was divided near 

 its middle by a permanent wire-screen partition, 

 and had good ventilation. The other, known as 

 the " infected-clothing building," was purposely 

 so constructed as to exclude anything like efficient 

 ventilation. Both houses were provided with 

 wire-screen windows and double wire-screen doors, 

 so that mosquitoes could be kept without or 

 within the buildings. 



The first mosquito infection was obtained on 

 Dec. 8. One of the volunteers, Kissinger by 

 name, had been bitten by five mosquitoes which 

 had previously been allowed to bite a yellow-fever 

 patient. On Dec. 8 he came down with a well- 

 marked case of yellow fever. He had been under 

 strict quarantine for fifteen days, so that the 

 possibility of any other source of infection was 

 removed. Within the period of one week from 

 Dec. 9 to Dec. 15, 4 of the volunteers who 

 had allowed themselves to be bitten by infected 

 mosquitoes developed well-marked cases of yel- 

 low fever. And of the 14 non-immune individuals 

 subjected to the bites of infected mosquitoes dur- 

 ing the whole test, 10 contracted yellow fever, 

 the attack always following the bites within the 

 period of incubation of the disease. Of 5 indi- 

 viduals who received direct injections of blood 

 from yellow-fever patients, 4 contracted the dis- 

 ease. On the other hand, 7 non-immune Ameri- 

 cans who slept every night in the " infected-cloth- 

 ing building," poorly ventilated, and to which no 

 sunlight ever came, engaged in the morning in 

 packing boxes with garments much soiled by 

 contact with the bodies and excreta of yellow- 

 fever patients, and at night unpacking these 

 same boxes in order to obtain articles for their 

 beds, and clothing for their bodies. Sleeping in 

 the very beds and garments just vacated by yel- 

 low-fever cases, these 7 men came out of this 

 pest-house at the end of the experiment perfectly 

 well, not one of them having contracted the dis- 

 ease. The " infected-mosquito building," divided 

 into two compartments by a wire-screen partition, 

 was next used as follows: Fifteen mosquitoes were 

 freed on one side of the partition, and a non- 

 immune man, Moran, was placed in the room. 

 On the other side of the partition, protected from 

 the mosquitoes, were 2 other non-immunes. 

 Moran was bitten freely by the mosquitoes, and 

 soon developed a sharp attack of yellow fever, 

 while the 2 non-immunes on the other side of 

 the screen remained perfectly well. The next ex- 

 periment was on one of the non-immunes who had 

 occupied the " infected-clothing building " for 

 twenty-one nights, and had then been kept in strict 

 quarantine thirty days longer. He visited the 

 mosquito room, was freely bitten, and in three 

 days and twenty-three and a half hours developed 

 a well-marked case of yellow fever. 



These experiments appear to leave no possible 

 doubt regarding the ability of the mosquito to 

 cause yellow fever, and also point strongly to the 

 absence of any infection due to simple contact 

 with yellow-fever patients or their excreta or 

 clothing. If this be true, the elaborate system of 

 quarantine now in vogue against the disease, and 

 the severe disinfection practised with yellow-fever 

 patients and their belongings, are quite unneces- 

 sary. Dr. A. H. Doty, health-officer of the port 

 of New York, says : " Dr. Reed's experiments have 

 not conclusively shown that there may not be 

 some other means than the mosquito by which 

 yellow fever is transmitted. But when the ex- 

 periments are considered in connection with the 

 results of our practical experience, it is clearly 



evident that the disease is not eonliueted by per- 

 sonal contagion or through the medium of cloth- 

 ing, bedding, cargoes of vessels, ete. 'I den-fore 

 1 believe we arc justified in ehan^in^ our <|ii;iran- 

 tine regulations to conform to the>'e views, and 

 that such a proceeding is safe arid reasonable, par- 

 ticularly as we now have at hand a method \\-hieh 

 if properly and scientifically carried out. fan !>o 

 depended upon to limit the extension of yellow 

 fever. If the future shows that there are' other 

 means of infection, it will then be time enough to 

 add whatever restrictions are necessary for the 

 protection of the public health. I am convinced in 

 following this action we are not only offering 

 full protection to the public, but are extending to 

 commerce a relief from unnecessary and unreason- 

 able regulations." 



The identification of Stegomyia fasciata the 

 yellow-fever mosquito is not difficult. Its most 

 conspicuous markings are a broad semilunar sil- 

 very stripe, which is seen on the lateral surface of 

 the thorax, and the white stripes at the bases of 

 the tarsal joints. The four stripes of silvery scales 

 that are seen on the posterior surface of the 

 thorax serve to distinguish the species from all 

 other mosquitoes except Stegomyia siynifer, in 

 which, according to Prof. L. O. Howard, the 

 curved thoracic band is very narrow and of a 

 somewhat different shape. When examined with 

 a lens, the four stripes are seen to consist of two 

 lateral distinct silver lines the combination of 

 the semilunar broad stripes and two fine white 

 lines between these. The insect must be held in 

 the proper light, in order that these delicate 

 threads may be distinctly seen. The lateral sur- 

 face of the thorax is also marked by several sil- 

 very dots, and the abdomen by distinct white 

 stripes. In the female the palpi are short, as in 

 the genus Culex. The species is found all over 

 Cuba, and has been reported from several Euro- 

 pean countries and from points in Central and 

 South America. In the United States, according 

 to Prof. Howard, it has been found at New Or- 

 leans, in eastern Texas, at Hot Springs, Ark., at 

 Pelham, Ga., and near Norfolk, Va. 



The methods recommended for the destruction 

 of this mosquito, which breeds in small bodies of 

 stagnant water, as does the malaria-bearing mos- 

 quito, are similar to those used against the lat- 

 ter. According to Dr. Reed's observations, this 

 mosquito will not bite when the air temperature 

 is below 62 F. He also says that an interval 

 of not less than twelve days is necessary after 

 the infection of the mosquito before its bite is 

 capable of causing yellow fever. 



The problem of preventing a yellow-fever epi- 

 demic when a case is imported into a city resolves 

 itself into two simple factors: First, to prevent 

 any mosquitoes from gaining access to the pa- 

 tient; and second, destroying all that may have 

 previously bitten him. The danger of the im- 

 portation of infected mosquitoes in baggage and 

 freight is very slight, as the mosquito, when de- 

 prived of water, perishes in a few days five days, 

 according to Dr. Reed's observations. 



For destroying mosquitoes that may have al- 

 ready become infected, pyrethrum powder or sul- 

 fur is said to be effective. The former, in the 

 proportion of 4 ounces to 1,000 cubic feet of air, 

 will stupefy all the mosquitoes in a tightly-closed 

 room in. one hour. They fall to the floor, and 

 may be swept up and burned. Sulfur burned, in 

 the proportion of one pound to 1,000 cubic feet 

 of air, effectively destroys all mosquitoes in a 

 closed room. The result of the application of 

 these discoveries to the city of Havana, in 1901, 

 caused a reduction in the mortality from yellow 



