A STATISTICAL STUDY OF THE PREVALENCE OF 
INTESTINAL WORMS IN MAN. 
By Ch. Wardell Stiles. Ph. D.„ Chief of Division, and Philip E. Garrisox.q A. B.. M. D.. 
Technical Assistant. & 
Division of Zoology. Hygienic Laboratory , U. S. Public Health and Marine-Hospital Service. 
SUMMARY. 
In order to determine the frequency and the species of intestinal worms present in man 
in at least two localities in the United States and to bring out other facts relating to the pres- 
ence of worms in the human intestine, we have examined 3.457 persons. These persons 
were inmates of the United States Government Hospital for the Insane (St Elizabeth) and 
of an orphanage, both of which are in the District of Columbia, and of the Connecticut Hos- 
pital for the Insane at Middletown. Conn. 
Of the 3.457 persons. 349 were infected with intestinal worms, an average of 10.10 per 
cent : 35 of the 349 infected persons harbored 2 species of parasites, and 1 person was infected 
with 3 species, making a total of 386 infections, or an average of 11.17 infections per 100 
persons. * 
Seven species of worms were found. They occurred in the following order of frequency: 
Whipworms. Trichuris (7.69 per cent), pinworms. Oxyuris (1.30 per cent), hookworms 
(1.04 per cent), eelworms. Ascaris (0.49 per cent), dwarf tapeworms. Hymenolepis nano, 
(0.35 per cent), Cochin China worms. Strongyloides (0.23 per cent), beef tapeworms. Tsenia 
saginata (0.06 per cent). 
The rates of infection found among our cases for whipworms, pinworms. eelworms. and 
for beef tapeworms are, in general, much lower than the rates reported for these parasites 
from other similar investigations: the minimum, maximum, and average rates of infection 
for these species, compiled from all the statistical data on the subject at our command 
(other than our own investigations), are. respectively, as follows: Whipworms. 2.31 percent, 
89.65 per cent. 12.69 per cent: pinworms. 0.07 per cent. 30.16 per cent. 7.24 per cent: eel- 
worms. 5.83 per cent. 37.39 per cent. 16.35 per cent : beef tapeworms. 0.07 per cent. 3.66 per 
cent. 0.40 per cent. 
Of the 36 infections with hookworms, 21 occurred in persons admitted to the Government 
Hospital from distant localities, and 14 of these infections in soldiers returned from service 
in the Philippine Islands. That the dwarf tapeworm should present 12 infections among 
our cases and the beef tapeworm only 2 is contradictory to the generally accepted opinion 
regarding the relative frequency of these cestodes in this country. Eleven of the 12 
in'eetions with the dwarf tapeworm occurred in males, 6 of the 12 in male children, and 5 of 
the 12 in male negroes. 
a Commissioned in U. S. Navy as Assistant Surgeon, June, 1906. 
&In making these numerous examinations we have been assisted by Arthur L. Murray, 
M. D.. David G. Willets. Ph. B.. Brayton H. Ransom, M. A., Earl C. Stevenson. M. D., and 
William F. Hemler, M. D. 
o 
