318 THE ROUND WORMS 



f -I -M -I C 



In medical books the embryos have been designated Filaria sanguinis hominis. 

 This species is the cause of the common manifestations of filariasis, such as elephanti- 

 asis, varicose groin glands, chyluria, lymph scrotum, etc. 



Filarial diseases are prone to lymphangitis attacks. Thus in lymph scrotum an 

 erysipelatoid condition of the scrotum with high fever and chills may result. This 

 condition is at times mistaken for malaria. Varicose groin glands may be mistaken 

 for hernia. In the Philippines very few symptoms are noted in those affected with 

 filariasis. Occasionally chylocele or chyluria is reported. 



F. bancrofti lives in lymphatics of trunk and extremities. At times the fine white 

 thread-like worms may be seen as writhing coils in lymphatic glands. 



The sexes are usually found together. The females are about 3 inches long 

 and the males less than 2 inches. The tails of both sexes are incurved, but that of 

 the male is more so. The head is club-shaped. The vulva opens 1.2 mm. from the 

 anterior end. There are two uterine tubules. The sheathed embryos are supposed 

 to be born viviparously and Manson supposes that as a result of injury to the 

 parent worm and resulting extrusion of eggs, the blocking of lymph channels occurs. 



A very interesting fact is that people with elephantiasis fail to show larvae in the 

 peripheral circulation. Manson considers that it is due to the blocking of the 

 lymph channels. 



These embryos show a nocturnal periodicity. During the day they 

 remain in the lungs, and larger arteries. 



If the patient sleeps in the daytime and is active at night the nocturnal perio- 

 dicity or presence of embryos in peripheral circulation is inverted. In the case of 

 F. loa, however, a change of habits does not change the periodicity of the filarial 

 embryos, they continue to appear in the peripheral circulation by day even if the 

 patient sleeps at that time. 



The disease is transmitted especially by Culex fatigans. The sheathed embryos, 

 getting into stomach of mosquito, wriggle out of the sheath, they then bore their 

 way through walls of stomach and enter into a sort of passive stage, during which 

 further development takes place. They finally become distributed in the muscles 

 of the thorax and make their way along the fleshy labium, to enter the wound in 

 a person bitten by a mosquito, by way of Button's membrane. This development 

 takes about twenty days at which time the larvae are about }/\ inch long and have 

 an alimentary canal. It was formerly considered that the filarial worm of the 

 Philippines was a different species, this from a study of microfilariae (F. phil- 

 ippinensis). Others, however, have considered the microfilariae as identical with 

 F. bancrofti. Recently Walker has published drawings and descriptions of four 

 adult filar iae in the Philippines which correspond to F. bancrofti. 



Filaria perstans. The adults are found in connective tissue and deeper fat, 

 especially about the mesentery and abdominal aorta. 



The female is about 3 inches (75 mm.) long; the male is rarely found and is less 

 than 2 inches long. These worms are characterized by incurved tails, the extremity 

 of which has two triangular appendages giving a bifid appearance. The embryos do 

 not possess a sheath and have a blunt tail. The life history is unknown. Both 

 mosquito and tick have been incriminated. The embryos are always present in 



