no 



CHAPTER X. 



OTHER FILARIA. 



Filaria perstans is a smaller and much weaker worm 

 than F. bancrofti. The head is larger but the body 

 is thinner. The tail of the female is slightly curved, and 

 at the tip are two prominent cuticular thickenings. The 

 male has well-marked pre- and post-anal papillae. This 

 worm is found in Africa and amongst the aboriginal 

 Indians in British Guiana and probably in other parts 

 of South America. It is common in well-wooded places 

 where the temperature is high and the air moist. 



The adult forms are found in connective tissue in the 

 vicinity of the alimentary canal, at the root of the 

 mesentery, and occasionally in the posterior medias- 

 tinum. They do not appear to give rise to any local 

 trouble. 



At one time it was suggested that sleeping sickness 

 might be due to this worm, but since the discovery that 

 that disease is the terminal stage of infection with the 

 Trypanosoma gambiense this hypothesis has been aban- 

 doned. No symptoms are known to be caused by 

 F. perstans. The intermediate host is unknown. Many 

 species of mosquitoes have been proved not to carry the 

 disease. It is so common to find in one village practi- 

 cally everybody infected, and in another near it no one 

 that in all probability the carrier is a common domes- 

 ticated arthropod that does not travel tar and that does 

 not remain infective for long periods or transmit the 

 infection to a second generation. Ornithodorus nwiibata 

 would fulfil these conditions in Africa. 



Filaria deniarquayi is found in many of the West 



