AN ACCOUNT OF THE TAPEWORMS OF THE GENUS HYMENOLEPIS PARA- 
SITIC IN MAN, INCLUDING REPORTS OF SEVERAL NEW CASES OF 
THE DWARF TAPEWORM (HYMENOLEPIS NANA), IN THE UNITED 
STATES. 
(Prepared under the direction of Ch. Wardell Stiles, Chief of Division of Zoology.) 
By Brayton H. Ransom, M. A.,« 
Assistant in Division of Zoology, Hygienic Laboratory, United States Public Health and 
Marine- Hospital Service. 
SUMMARY. 
The present paper comprises a full account, from both zoological and medical 
standpoints, of the representatives, three in number, of the tape^^orm genus Hymen- 
olepis, parasitic in man. This genus has received but slight attention from American 
authors. Recent indications, however, point to the probability that one species of 
this genus, Hymenolepis nana, the dwarf tapeworm of man and rats is, compared with 
other tapeworms, not an uncommon parasite of man in this country. Owing to its 
small size, and the necessity of depending for a diagnosis of its presence upon the 
discovery of its eggs in the feces by microscopical examination, it is undoubtedly 
frequently overlooked. About 100 cases altogether of this parasite have been 
reported from man.& Eleven cases have been found in this country during 1902- 
1903 — in Texas, Georgia, South Carolina, and the District of Columbia. 
The tapeworm in question was first described, upon the basis of specimens from 
rats, in 1845, by Dujardin, as Tsenia murina [not Gmelin, 1790] ; it was first noticed 
in man by Bilharz at Cairo, Egypt, in 1851, and a description under the name of 
Tsenia nana was published by Siebold (1852). The earlier name, T. murina, had 
already been used for another form by Gmelin in 1790, and the name nana is accord- 
ingly retained as the correct specific designation. 
It has been proved experimentally by Italian investigators that when eggs of this 
parasite are swallowed by white rats, the embryos hatch, bore into the intestinal 
« Transferred June 1, 1903, to U. S. Bureau of Animal Industry, as Assistant Zoologist. 
& Since the manuscript of this paper was finished, six more cases have been found 
by this laboratory in the District of Columbia, among 123 children in orphan asylums. 
Several probable cases have been reported to us by letter by Dr. J. B. De Veiling, 
Jackson, Miss. Dr. L. E. Magnenat, of Amarillo, Tex., has found four cases in a 
single family (Stiles, 1903c). Finally Dr. H. M. Hallock (1904a), of the U. S. Army, 
has reported two cases at Fort Porter, Buffalo, N. Y., in soldiers recently returned 
from the Philippines. This makes altogether for the United States something over 
25 cases, all but.one having been recorded since August, 1902, and 16 of which have 
been found by members of this laboratory in a systematic examination for intestinal 
parasites of about 3,500 persons. It is significant that in these examinations only 
two cases of the beef-measle tapeworm, Tsenia saginata, and none of the pork-measle 
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