CULEX AND FILARIASIS 37 



to escape. And this was in all probability given it 

 when the mosquito sought a fresh victim to get its 

 meal of blood. During this act it is supposed that 

 the parasite escapes into the tissues of the victim. 

 From these observations it seems highly probable that 

 filaria disease is transmitted from a person in whose 

 blood tlie parasites are present by the intermediate 

 host, the mosquito, which in its turn infects man 

 when it bites him. JNIan harbouring the parasite is the 

 reservoir, the mosquito is the carrier. It will be ob- 

 served that the carrier is the " mosquito " — often a 

 species of Culcw. But this function does not appear 

 to be limited, as is malaria, to the Anophelines, or, 

 as in yellow fever, to the Stegomyia, probably several 

 species of mosquito being able to act as hosts. But as 

 in the case of malarial parasites, so in the case of the 

 filaria, the parasite passes part of its existence in man 

 and part in the mosquito ; hot/i man and the mosquito 

 are necessary for the complete devc/opment of the 

 parasite. 



Therefore, if the mosquito is destroyed, the life- 

 cycle of the parasite is destroyed and the disease nnist 

 of necessity cease. This constitutes, as we said in a 

 former chapter, the fundamental principle of prophylaxis 

 in all the mosquito-borne diseases. 



