308 MOSQUITOES OF NORTH AMERICA 
worms and as larve or so-called microfilarize. The adult filarie are found in 
the lymphatic vessels or in the connective tissues in various parts of the body. 
The two sexes are usually associated, coiled about each other, and sometimes 
several are coiled together. The larvee to which the female worm gives birth 
find their way, in large numbers, into the blood and sometimes into the urine. 
Man is the host of several species of Filaria, and, as in the case of the malarial 
organisms, more than one of these may be present in the same individual. 
Only one species of Filaria is of marked pathological importance. This is 
Filaria bancrofti, also frequently designated as Filaria (or Microfilaria) noc- 
turna or Filaria sanguinis-hominis. The presence of this parasite does not 
necessarily produce sickness; in fact it is well known that the filarie are often 
present without the host showing any symptoms and they are only detected when 
the blood is examined. However, a series of pathologic conditions are produced 
by the presence of filaris in man, which, while they are seldom directly fatal, in- 
capacitate to a greater or less degree. Manson, who is probably the best 
authority on filariasis, gives as the result of the parasitism of Filaria bancrofti 
in man the following filarial diseases : 
“ Abscess; lymphangitis; varicose groin glands; varicose axillary glands; 
lymph scrotum; cutaneous and deep lymphatic varix; orchitis; chyluria; ele- 
phantiasis of the leg, scrotum, vulva, arm, mamma, and elsewhere; chylous 
dropsy of the tunica vaginalis; chylous ascites; chylous diarrhoea, and probably 
other forms of disease depending on obstruction or varicosity of the lymphatics, 
or on death of the parent filarie.” 
Filariasis is a widely distributed disease in tropical and subtropical regions 
and is especially common on the west coast of Africa, in South China, certain 
parts of India and some of the islands of the Pacific. In certain islands of the 
Society and Tonga groups, according to some observers, fully 70 per cent of the 
population are afflicted with filariasis. In America it is very prevalent in the 
West Indies. Dr. Mario G. Lebredo, in a recent paper, states that in the city of 
Havana he found 17.82 per cent of filaria infection. He points out its dangerous 
character and that there is reason to fear its general spread unless effective con- 
trol measures are adopted. In the United States cases are occasionally found 
in the Southern States and isolated cases occur further north, but it can not be 
considered endemic. The forms of the disease appear to vary considerably ac- 
cording to locality and on this account the belief has been expressed that more 
than one species of Fularia is included under the name Filaria bancrofti. 
TRANSMISSION BY MOSQUITOES. 
The suggestion that mosquitoes are probably the carriers from man to man 
of at least one of the parasitic worms of the genus Filaria, in one stage or 
another, apparently was made about the same time by Bancroft, in Australia, 
and Manson, in China. The evidence was first gained by Manson about 1878, 
who thus became the discoverer of the first recognized transfer of a disease or- 
ganism by mosquitoes. Manson found that mosquitoes which feed upon filarial 
blood become infected and that the filarie undergo a metamorphosis within the 
