APPENDIX.* 



THE HEREDITAEY TRANSMISSION OF THE VIRUS OF 

 YELLOW FEVER IN THE STEGOMYIA FASOIATA. 



By E. Mahchoux and P. L. Simond. 



Among the new facts concerning yellow fever which we gathered in 

 Brazil there is one the importance of which obliges us to publish at 

 once. It concerns the question of the possibility of the hereditary 

 transmission of the yellow fever virus from mosquito to mosquito. 

 » Since 1903 our attention has been turned to the fact that in certain 

 foci of an epidemic zone it is at times difficult to find a case of yellow 

 fever of recent date as the origin of the new cases which spring up at 

 a given time. There being no doubt that the lighting up of these foci 

 was due to the presence of infected Stegomyia faseiata, we were forced 

 to conclude that one or several of these mosquitoes had in some way 

 been imported from a distant point where the disease existed from 

 which they had drawn the virus. This undoubtedly occurs frequently. 

 We, nevertheless, were led to ask ourselves if, under certain circum- 

 stances, eggs derived from a Stegomyia infected in the course of an 

 epidemic some months prior to the one observed could not have given 

 birth to Stegomyias hereditarily infected. 



Several experiments were made in 1903 to confirm this hypothesis. 

 We had some Stegomyias lay eggs that had stung some cases early in 

 the disease. -The eggs were hatched into larvae, and the adult insect 

 raised from these was made to sting a human subject. 



These experiments did not give us positive results at that time, 

 although the subjects that had been bitten by these mosquitoes were 

 not immune to the disease, for subsequently it was possible to give it 

 to them by injections of fresh virulent serum. 



We resumed these experiments in February, 1905. We collected a 

 number of eggs of one laying from a Stegomyia 20 days old which 

 had stung several of our cases in order to determine a heavy infection, 

 and the larvae which were hatched the 4th of February were placed in 

 a jar to be reared. The adult insects began to emerge February 16. 

 These, isolated in tubes from the time of emergence, were fed with 



a Translated from Comptes Rendus, SocWte' Biologie, Paris, Vol. LIX, No. 27. 



August 4, 1905, p. 259. 



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