12 
once; Oxyuris and Hymenolepis, once; hookworms and Strongyloides, 
once; Trichuris, hookworms, and Ascaris, once. Thus, among the 
349 ififected persons there were 386 infections, an average of 11.17 
infections for each 100 persons examined. 
Relative frequency of the different parasites. — The different 
species of worms were present in the following relative frequency: 
Infections. 
Per cent. 
Trichuris trichiura 
Oxyuris vermicularis . . . 
Hookworms 
Ascaris lumbricoides ... 
Hymenolepis nana 
Strongyloides stercoralis 
Tsenia saginata 
266 
45 
36 
17 
12 
8 
2 
7.69 
1.30 
1.04 
0.49 
0.35 
0.23 
0.06 
Over two-thirds of the total number of infections were with the 
whipworm ( Trichuris trichiura), while ‘the eelworm (Ascaris lumbri- 
coides), which is frequently stated to be the most prevalent intestinal 
worm of man and which presents about the same frequency as whip- 
worms in other investigations (see p. 65), occurred only 17 times, 
namely, in about 0.5 per cent of the persons examined. As indicated 
in the introduction, the figures for the pinworm ( Oxyuris ) (1.30 per 
cent) in all probability do not fully represent the true frequency' of 
that worm. Tsenia saginata has been said to occur in about 1 per 
cent of the population, this opinion being expressed upon certain 
results of foreign investigators and its occurrence in. the practice of 
physicians. Our much lower rate of 0.06 per cent would seem to 
indicate either that the prevalence of this parasite in the United 
States has been overestimated or that it is decreasing in frequency as 
a result of meat inspection, cold storage, etc. As will be shown, the 
infections with hookworms occurred for the most part among soldiers 
who had returned from service in the Philippine Islands. Perhaps 
the most striking result of our work is the finding of 12 cases of infec- 
tion with the dwarf tapeworm (Hymenolepis nana). Only about 121 
cases of infection with this cestode have been reported for man; about 
27 of these (including our 12 cases and the cases found by Stiles in the 
Southern States in 1902) occurred in the United States. As Stiles 
has claimed in an earlier paper, there is strong indication that the 
dwarf tapeworm is the most common tapeworm in man in certain 
parts of this country. 0 
a As an addition to the North American cases of infection with this worm thus far recorded 
we can now add a case in Statesville, N. C., diagnosed upon microscopic examination of 
feces sent to us by Dr. H. F. Long, August, 1895. 
