8 
villi, become transformed into an intermediate stage (cercocysts) , and later fall again 
into the lumen of the intestine to become adult. It is presumed that a similar devel- 
opment occurs in man, although the possibility remains that development, both in 
man and in the rat, may also occur by means of some intermediate host, such as an 
insect, not yet determined. 
From the clinical side abstracts of 106 cases are given. Five of these are here 
reported for the first time. 
Most of the cases have been in males and the large majority in children, commonly 
between the ages of 5 and 10 years. 
Thirty-eight of the cases were found in the inmates of orphan asylums, a poor- 
house, and an insane asylum, and more cases have been reported from cities than 
from rural districts. Children in bad hygienic surroundings seem especially liable 
to infection, and institutional life seems to favor the occurrence of the dwarf tape- 
worm, both in children and in adults. 
The prevalence of infection has been estimated as 10 per cent among the children 
of Italy. In the Government Hospital for the Insane, Washington, the parasite has 
been found in 0.3 per cent of about 2,000 patients examined. In about 160 fecal 
examinations recently made by* Stiles (1903a) in the Southern States, the percentage 
of occurrence of H. nana was 0.25 per cent. 
The largest number of cases from one State or country, 65, has been reported from 
Italy; the District of Columbia ranks second with 6 cases. The geographical distri- 
bution of the parasite as recorded for man accords very well with the distribution of 
the parasite as recorded for rats, and is practically cosmopolitan like that of its hosts. 
The part of the intestine infected is the ileum. 
The number of worms present in any one case varies from a single specimen to 
several thousand. 
Simultaneous infection with other parasites is common. As many as four other 
species of parasites have been found occurring with H. nana. 
Infection may persist from 2 months to 2i years, perhaps to 5 years, and longer, 
or until terminated by successful treatment. 
Comparison with statistics relative to larger tapeworms indicates that the symp- 
toms produced by the presence of II. nana, while not more severe, apparently occur 
with greater frequency in a severe form in cases of H. nana than in cases of the 
larger tapeworms. This circumstance, however, is considered not to indicate a 
greater nocuity of the smaller worm; it is simply due to the fact that a relatively 
greater number of cases are overlooked. 
The symptoms produced by the dwarf tapeworm are usually slight, and may be 
absent entirely, even though the worm be present in large numbers. Severe symp- 
toms, however, such as persistent diarrhea, epileptiform attacks, etc., occasionally 
occur. The most frequent symptoms are abdominal pain, with or without diarrhea; 
convulsions of various sorts, frequently epileptiform; headache and strabismus. 
Nasal and anal pruritus, common in cases of infection with other tapeworms, are 
tapeworm, Tsenia solium, were found. These facts continue not only to bear out the 
original assumption of Doctor Stiles that the dwarf tapeworm is going to prove a 
common American parasite, but seem to indicate, furthermore, the likelihood that 
it will turn out to be the most common of the tapeworms parasitic in man in this 
country. 
In October and December, 1902, the examination of 60 children 1 to 15 years old. 
At a hospital in Buenos Aires, Argentina, showed 11 cases of infection with H. nana. 
fLynch, 1904.) On a prior occasion 101 children were examined and no cases were 
found. Lynch considers the results of these examinations to indicate that the para- 
site is becoming more common in Argentina, and suggests the likelihood of many 
cases having been introduced by Italian immigrants, large numbers of whom have 
come into the countrv in recent vears. 
