PATHOGENIC EFFECTS 261 



prevents the coagulation of blood; (4) the entrance of harmful 

 bacteria and other microscopic organisms into the wounds made 

 by the worms, resulting in the absorption of bacterial toxins and 

 in the formation of dangerous lesions; (5) a thickening and de- 

 generation of the mucous walls of 

 the intestine; and (6) the secretion 

 of poisonous substances or toxins 

 from glands in the heads of the 

 worms. These poisonous secre- 

 tions, which have blood-destroying 

 properties, probably account for 

 more of the symptoms of hook- 

 worm disease than does anything 

 else, though apparently they have 

 widely different effects on different 

 individuals. Sometimes the pres- FlG - 105 - American hookworm; 



,, . ,1 i section showing manner of attach- 



ence of eggs in the iaeces is the only ment to intestinal wall. (After 

 indication of infection. Negroes as Ashford and igaravidez, from photo 



r , , ., .,., by Dr. W. M. Gray.) 



a class show far less susceptibility 



to the poisons produced by hookworms than do the whites; this 

 is especially well demonstrated in our southern states. The 

 symptoms are more severe in summer than in winter, very 

 probably due to the greater abundance of worms in the summer. 



Hookworm disease is almost always preceded by a case of 

 ground itch, due, as remarked above, to irritation from the boring 

 of the worms and to secondary infection with bacteria. The 

 commonest symptom of the disease is anemia, usually accom- 

 panied by some fever or dyspeptic trouble, though often in mild 

 cases there is no evident emaciation. The significant name " el 

 palido " (the pale one) is applied to the hookworm victim on the 

 coffee plantations of Porto Rico. In severe cases of long stand- 

 ing the anemia and loss of vitality become extreme and so weaken 

 the patient that he succumbs to the least unfavorable circum- 

 stance ; his unhappy career is usually ended by some slight illness 

 which in normal health he could easily have resisted. In Porto 

 Rico about 30 per cent of all deaths are attributed to hook- 

 worm. 



Both the mental and physical development become abnormal. 

 A child of 12 or 14 years may have the degree of development 

 which should belong to an average child of six or eight and a 



