PATHOLOGY 



1763 



Commission confirms the suspicion which had long existed as to 

 a relative racial immunity, finding 71 per cent, of the cases in 

 Europeans, 54 per cent, of the cases in mulattoes, and 41 per cent, 

 of the cases in negroes, to vary from medium to very severe, though 

 the degree of infection of the three races was in the proportions 

 of 78 per cent., 72 per cent., and 76 per cent. 



With regard to the two worms it is useful to note that Ancylostoma duodenale 

 is larger and coarser looking, with thicker and coarser head, armed with four 

 hooks on the buccal rim, and with the dorsal conical tooth not markedly pro- 

 jecting into the mouth. Female with sexual opening in the posterior third, 

 Male with larger caudal bursa, with dorsal lobe. Ova slightly smaller. 

 Necatov americanus is smaller, with small and finely tapering head, simple 

 chitinous lips on the buccal rim, dorsal conical tooth projecting well into the 

 mouth. Female with sexual opening in the anterior half of the body. Male 

 with smaller bursa and subdivided dorsal lobe. Ova sUghtly larger. 



Fig. 755. — Case of Ankylostomiasis. 

 (Note the swollen face.) 



Pathology. — ^When the embryos enter the skin in sufficient 

 numbers they cause an eruption of papules or vesicles, but some of 

 these are more probably due to the pyococci and bacteria introduced 

 along with the larvae, which are the true cause of the dermatitis, as 

 alcoholic extracts of the larvae are said to produce similar lesions. 

 These skin lesions are called ' bunches ' in Cornwall, ' mazamorra ' 

 in Porto Rico, and ' ground-itch ' in Assam. Smith has shown that 

 experimental dermal infection with N. americanus causes local 

 itching and a macular eruption, followed next day by a vesicular 

 rash and swelHng of the part, and on the fifth day marked swelHng 

 and enlargement of the lymph glands. This dermatitis disappears 

 by the twelfth day. There may be sore throat and uneasy sensa- 

 tions in the stomach for a few weeks, and the ova appear in the 

 faeces about the middle of the seventh week. 



