308 PILARIS AND THEIR ALLIES 



it is confined to regions of heavily forested tropical swamps. 

 In some districts in Uganda it has been found in 90 per cent of 

 the inhabitants. The microfilariae of this species (Fig. 124B) 

 are smaller than those of F. bancrofti, have a blunt tail and 

 lack the sheath which is so characteristic of F. bancrofti. Fur- 

 thermore they show no tendency to disappear periodically from 

 the peripheral vessels. The adult worm, which has rarely been 

 found, is smaller than F. bancrofti (about three inches in length) 

 and occurs in the connective tissue of the abdominal and peri- 

 cardial cavities. The normal transmitting agent, probably some 

 species of mosquito, is not certainly known. No disease symp- 

 toms which can be correlated with the presence of the parasite 

 have yet been demonstrated. 



Another species, F. juncea (demarquaii), of which the larva 

 (Fig. 124D) is small and without a sheath, as in F. perstans, but 

 with a sharp tail, occurs in the West Indies and northern South 

 America. It is not known to cause any diseased conditions. 

 The adults live in the mesenteric tissues. In many Indians in 

 British Guiana F. perstans and F. juncea occur together in the 

 blood, and in some cases the presence of F. bancrofti compH- 

 cates the matter still more. 



F. magalhaesi is another species about which very little is 

 known. A pair of adult worms were found only once, in the 

 heart of a child in Rio de Janeiro. They were of unusually large 



size, the female measuring over six inches in 



length and the male about three and a half 



inches. Nothing is known of the life history 



or pathological effects. 



The Loa Worm. — Of somewhat different 



nature from the above species of Filaria is F. 



loa or Loa loa (Fig. 128), a parasite found on 

 loa^' worms,' ffmaie ^^'^^ ^^^^ ^oast of Africa, especially in Congo, 

 (9) and male ($). Avhich, as an adult, creeps in the connective 

 Loorj^t ^''''' *^'^ tissue of its host just under the skin. The 



female varies, probably with age, from two to 

 two and one-half inches in length, and is semi-transparent and very 

 slender. The male resembles the female, but is only from one to 

 one and one-half inches in length. Both sexes are characterized 

 by numerous irregularly distributed pimple-like elevations of the 

 skin. The loa worm shows a special preference for the connective 



