EXAMPLES OF MOSQUITO EXTEBMINATTVE MEASURES. 97 



with the patient and stops the entrance of any gas which may possibly find its way 

 through some overlooked crevice. During the preparation for disinfection the sani- 

 tary authorities make a thorough inspection and destroy any mosquito larva they 

 find, pick up or destroy any vessel* lying about which might serve as a receptacle 

 for mosquito-breeding water, and close water boxes against the same danger. The 

 patient remains in isolation for seven days, after which isolation may terminate, if the 

 family so wishes. The infected district is then treated as above indicated; that is, by 

 disinfection, sanitary policing, and medical supervision. Disinfection is carried 

 on in two ways, one force working from the center toward the outer limits of the 

 district and the other from the boundaries of the district inward. The area of 

 infection being determined over as large an area as possible, these two sections sepa- 

 rate, one of which begins immediately with the house in which the case of yellow 

 fever occurred, the other beginning at those houses which might possibly have been 

 infected at the greatest possible distance from the case in isolation. The purpose 

 of such a system was to destroy all mosquitoes which might have carried infection 

 within the district. 



While the disinfecting force is thus at work the police division, under the direction 

 of a physician and of students who direct the different sections, operates throughout the 

 infected district, making every effort to destroy all mosquito larvae and to prevent the 

 possible breeding of mosquitoes outside as well as inside the house. Where larvae are 

 likely to exist in stagnant water or refuse of any sort, petroleum mixed with creoline, 

 lysol, or similar products is thrown over the water or refuse in sufficient quantity to 

 kill the larvae instantly. Wh'ere it is impossible to use petroleum, as in the case of 

 tanks and boxes for household use, a small fish, the ; 'barrigudo*' or Girardinus caudi- 

 maculatus. is placed in large numbers in the water. This fish destroys the larvae of 

 mosquitoes most voraciously. Larvae in the drains are destroyed by the use of ''Clay- 

 ton gas, ' ' which is pumped into the sewer, which has been previously divided into com- 

 partments. Simultaneously with the disinfection the sanitary inspectors make daily 

 inspection of the suspected district, examining every inhabitant supposed not to be 

 immune— that is, children under 5, and all foreigners of less than 5 years' residence in 

 Rio. These are subjected to the closest vigilance, being placed in isolation at the 

 least tendency to rising temperature. Reports are made in writing, those to whom this 

 duty falls being required to fill out daily a bulletin sent out by the medical inspector 

 to the chief of each district. In this report must be given the record of any who work 

 outside the district or who for any reason absent themselves therefrom, a record of 

 their condition being also kept by the physician in the district in which they work or 

 are temporarily resident. When any inhabitant absents himself from the district the 

 record must show his address, where he will be subjected to vigilance on the part of the 

 authorities there. If the person under vigilance evades the attention of the physi- 

 cian and withdraws without giving notice, the owner of the house in which he lived 

 is fined, he himself is apprehended by the sanitary police, fined, and subjected to 

 renewed vigilance. 



The vigilance in each district extends over a period of one month after the appear- 

 ance of the last case. To give an idea of this service we will note the figures covering 

 the prophylactic campaign in the infected district about the cotton factory. "Fabrics 

 das Chitas," in 1906. The inspection was carried out by IS doctors, who examined 

 daily all suspected persons— in all, 7,966 persons, of whom 2,989 were not immune. 

 Sixty cases were reported, of which only 19 proved to be yellow fever, and the district 

 was declared entirely freed of infection after six months. With the combination of the 

 three systems there is no doubt about cleaning up effectively any district in which yel- 

 low fever may appear. In normal conditions the police service is carried out with 

 equal painstaking, especially in the districts where infection last appeared. When, 

 after some time, there seems no longer to be danger of new infection, the inspectors 

 allow water to stand in several marked spots most favorable to mosquito breeding. 

 37713— Bull. 88—10 7 



