THE HOOKWORM 



289 



FilaWia are small roundworms that cause various tropical dis- 

 eases — the most serious of which is elephanti'asis. The parasites 

 possibly enter the body in drinking water and some are probably 

 introduced by the bite of a mosquito. 



The Hookworm. — The account of the discovery by Dr. C. W. 

 Stiles of the Bureau of Animal Industry, that the laziness and shift- 

 lessness of the " poor whites " of the South 

 is partly due to a parasite called the hook- 

 worm, reads like a fairy tale. 



The people, largely farmers, become in- 

 fected with a larval stage of the hookworm, 

 which develops in moist earth. It enters 

 the body usually through a break in the 

 skin of the feet, for children and adults 

 alike, in certain localities where the disease 

 is cormnon, go barefoot to a considerable 

 extent. 



A complicated journey from the skin to 

 the intestine now follows. The larvae pass 

 through the veins to the heart, from there 

 to the lungs, where they bore into the air 

 passages, and eventually reach the intestine 

 by way of the throat. One result of the 

 injury to the lungs is that many thus in- 

 fected are subject to tuberculosis. The 

 adult hookworms, once in the food tube, 

 fasten themselves to the walls, which they 

 puncture; and then they feed upon the 

 blood of their host. The loss of blood from 

 this cause is not sufficient to account for 

 the bloodlessness of the person infected, but 

 it has been discovered that the hookworm 

 pours out into the wound a poison which 

 prevents the blood from clotting rapidly 

 (see page 164) ; hence a considerable loss 

 of blood occurs from the wound after the 

 hookworm has finished its meal and gone to another part of 

 the intestine. 



Hookworm, highly 

 magnified, and diagram 

 of course followed from 

 foot to heart, to lungs, to 

 throat, to intestine. Ex- 

 plain from text. 



