95 



In an investigation of the occurrence of F. bancrofti among the 

 native inhabitants of Weltevreden (Batavia) from December to 

 January 1921, the original plan of confining examination to permanent 

 residents failed, and this fact ultimately supplied the explanation 

 why filariasis is uncommon at Batavia in spite of conditions favourable 

 to it. The organism concerned appears to be Microfilaria nocturna, 

 and success attended attempts to infect Culex fatigans, Aedes 

 {Stegomyia) sctitellaris , Anopheles {Myzomyia) ludlowi a.nd A. subpictus 

 {rossi) with it. In these hosts the microfilaria develops in the 

 same manner as F. bancrofti. The first two proved to be the most 

 suitable carriers. 



The incidence of infection of F. bancrofti in both hemispheres is 

 recorded, showing that the figures for Batavia are much lower than 

 those for Africa, but do not differ greatly from those of countries 

 near Java. 



At Batavia there is a sufficient number of human carriers of Micro- 

 filaria bancrofti, and both climate and temperature are very favourable 

 to the spread of the parasite. Development in the mosquito is quickest 

 between 25° and 29° C. [77°-84° F.], when full-grown larvae occur 

 in the proboscis fourteen days after the mosquito has fed. In order 

 that a mosquito may infect man, the skin of the latter must be moist. 

 The warm, damp, coast climate of Batavia, where the mean temper- 

 ature is 27° C. [80°-6F.], is therefore very suitable. The fact that 

 only a small percentage of natives at Weltevreden and Batavia are 

 permanent residents supplies the explanation of the comparative 

 rarity of the disease. In a group of 1,112 persons examined, 216 had 

 been less than a year af Weltevreden, and the percentage of infection 

 among them was 2-3. Among the remainder the figure was 10-1 per 

 cent. The maximum number of larvae found in the blood of the 

 former was 110, with an average of 21. Among the others the figures 

 were 40 and 16. Temporary inhabitants are therefore not the source 

 of the infection, which appears to be endemic. As only infection and 

 reinfection during many consecutive years can ensure a large part of 

 the population becoming carriers, the temporary inhabitants serve 

 as traps for the Filaria, and leave the town before the larvae occur in 

 the peripheral blood. 



The author is of opinion that unless conditions change within the 

 next few decades filariasis is not likely to increase at Batavia. Active 

 measures against the disease will require the provision of an abundant 

 supply of good water, followed by the prohibition of cisterns and other 

 mosquito breeding-places. 



Dyar (H. G.). New Mosquitoes from Alaska. — Insecutor Inscitiae 

 Menstruus, Washington, D.C., x, no. 1-3, January-March 1922, 

 pp. 1-3. 

 Aedes punctodes, sp. n., larvae of which were obtained from pools 

 in the tundra, and Aedes prolixus, sp. n., are described. 



Dyar (H. G.). The American Aedes of the impiger {decticus) Group 

 (Diptera, Culicidae). — Insecutor Inscitiae Menstruus, Washing- 

 ton, D.C., X, no. 1-3, January-March 1922, pp. 3-8. 



The species here described are considered solely as they occur in 

 North America. It is probable that some of the same species occur 

 in northern Europe, and if this is the case, A. lazarensis, F. & Y., will 

 become a synonym of ^4. communis, DeG., but as the American forms 



