ETIOLOGY OF YELLOW FEVER 643 



tilt.-]. This has been confirmed by the French Commission, 

 with tin- additional result that the virus passes through a 

 ( 'liaiiil>er]and F filter, but not through a Chamberland B. These 

 facts would show that the parasite is of extremely minute size, 

 and apparently belongs to the group of ultra-microscopic 

 organisms. l. T p till the present time all attempts to find by 

 microscopic examination the yellow fever parasite, either in the 

 blood of patients suffering from the disease or in the tissues of 

 infective mosquitoes, have been attended with negative results. 

 It has U vii recently stated that it is possible to produce yellow 

 fever in the chimpanzee by the injection of blood from a patient. 

 Though nothing has been determined regarding the actual 

 nature of the virus, yet the results already obtained have 

 supplied the basis for preventive measures against the disease, 

 these being directed towards the destruction of mosquitoes and 

 the protection of those suffering from yellow fever, and also the 

 healthy, against the bites of these insects. Already a striking 

 dfgivc of success has been obtained in Havana. Such measures 

 came into force in February 1901, and in ninety days the town 

 was free of yellow fever, and for fifty-four days later no new 

 cased occurred; and although subsequently the disease was 

 reintroduced into the town, no difficulty was experienced in 

 stamping it out by the same measures. In recent years the 

 results have also been highly gratifying, and the disease may 

 be said to be practically eradicated from Havana. In other 

 places also successful results have been obtained, and epidemics 

 would ap]n'ir to be now under control if the proper measures 

 are taken. 



