116 



of lymph by the adult, or by immature ova, not by microfilariae in 

 the blood. The organisms multiply by sexual reproduction in the 

 lymphatic system only ; the embryos, escaping into the blood as 

 microfilariae, circulate, awaiting the opportunity of being imbibed by 

 a biting mosquito. The mosquito draws them into its stomach with 

 the blood. The microfilariae, after losing their sheaths, pierce the 

 stomach wall, and undergo metamorphosis in the thoracic muscles. 

 In about two weeks they migrate to the proboscis, in order to get 

 back into man when the mosquito again feeds. They then pass 

 by way of the lymphatics to the nearest lymph gland, where they grow 

 to maturity. 



If filariasis is compared with malaria, it will be seen that transmission 

 of the former is relatively difficult. The microfilariae do not multiply 

 in the body of the mosquito ; very few are imbibed by it, fewer still 

 survive the stages in the mosquito and finally reach the proboscis. 

 They are not injected by the mosquito bite, but are only dropped on the 

 skin of man, so that the number that penetrate it and reach a lymphatic 

 gland is smaller still. Even then, unless a male and a female find 

 lodgement in the same lymph gland, reproduction cannot take place. 

 Besides this a mosquito will probably become infected only if it bites 

 during the few hours of the night when the microfilariae are active 

 in the blood, and the bite of the infected mosquito can only cause 

 infection after two weeks and when the organism is actually in its 

 proboscis. Consequently filariasis cannot spread except in a locality 

 where there is mass blood infection and mass mosquito biting. In 

 the United States these conditions only occur in Charlestown. 



In Charlestown over 90 per cent, of the mosquitos are Culex fatigans 

 and dissections have shown them to be active carriers of Filaria 

 bancrofti. Another 9 per cent, are Stegomyia fasciata {Aedes calopus), 

 none of which carried the infection. 



As no drug is known that will eradicate microfilariae from the blood 

 stream, the disease must be attacked through the mosquito. A 

 municipal, piped water supply, coupled with an ordinance requiring 

 the destruction of all collections of water in which mosquitos might 

 breed, would rid a community of filariasis by reducing the numbers of 

 Culex fatigans to a negligible degree. 



In part iv of this paper is described the anatomy of the mosquito 

 proboscis in relation to filaria transmission, showing how on the 

 inward course the parasites pass with the blood through the proboscis 

 itself, while on the outward journey they travel by way of the proboscis 

 sheath and fall on to the intact skin clear of the wound the proboscis 

 has made. 



Malariabekampfung, Anophelenkarte fur Deutschosterreich. [Anti- 

 Malaria Work, Anopheline Chart for German Austria.] — Mitt^ 

 Volksgesundheitsanites, Vienna, no. 1, 11th April 1919, pp. 1-2. 

 [Received 12th April 1920.] 



A decree, dated 25th March 1919. of the National Health Depart- 

 ment of the Ministry for Social Administration refers to a previous 

 decree (13th January 1919) providing for the preparation of an 

 Anopheline Chart for German Austria and orders the local sanitary 

 authorities to enlist the help of zoologists in compiling this. 



