May 10, 1924 
Ascaris Sensitization 
579 
meat of infested calves often smells so strongly of Ascaris as to render it unfit 
for food. In view of these reports the possibility naturally suggested itself that 
persons sensitive to Ascaris might also be similarly sensitive to pork from infested 
hogs if such meat contained toxic elements absorbed from the parasites infesting 
the animals. If it were found to be true that Ascaris-sensitive persons were 
sensitive to pork from infested hogs, the fact would be of great importance in 
its bearing on the question of pork sensitization, especially if at the same time 
such persons were insensitive to pork from noninfested hogs, inasmuch as a great 
deal of the pork that is eaten comes from Ascaris-infested hogs. Examination 
of about 2,500 hogs of various ages slaughtered in Chicago packing houses a few 
years ago showed an average of 41.1 per cent infested ( 3 ). 
The following experiments were performed to determine whether pork from 
infested hogs contains a substance that will produce a skin reaction in persons 
sensitive to Ascaris. Aqueous, alcoholic, and ethereal extracts were made of pork 
from several infested hogs, and another similar series of extracts from a nori- 
infested hog. Alcoholic and ethereal extracts were also made of fat from infested 
and noninfested hogs, respectively. None of these extracts gave a positive 
cutaneous scratch test in three Ascaris-sensitive individuals. Another experi¬ 
ment in which an aqueous extract of pork sausage was tested on six individuals, 
three of whom were sensitive to Ascaris, also gave negative results. The sausage 
used was a composite sample of sausage from several large meat-packing estab¬ 
lishments. Any given lot of sausage manufactured in such establishments is 
likely to include trimmings from numerous hog carcasses, and in view of the 
frequent occurrence of Ascaris in swine the extract used in this experiment must 
have contained substances from the meat of a considerable number of infested 
hogs. 
The results of these experiments, while not absolutely conclusive because of 
their negative character, indicate that the meat of Ascaris-infested hogs does 
not contain the substance that causes an urticarial skin reaction in Ascaris- 
sensitive individuals. In the light of this evidence there is no reason to suppose 
that Ascaris sensitization is involved in cases of pork sensitization. 
Because of the writers’ desire to learn something of the nature of the substance 
or substances in Ascaris that cause symptoms in susceptible persons, and, also, 
if possible, to isolate a substance that might appropriately be used to desensitize 
Ascaris-sensitive individuals, one of the writers undertook to separate various 
fractions of the constituent substances of the parasite. It was not considered 
advisable to attempt desensitization of human subjects with the crude substances 
of the worm inasmuch as certain pathological changes in the adrenals, thyroid, 
pituitary body, and pancreas of experimental animals have been recorded by other 
investigators following repeated injections of small quanties of the verminous 
material. Other investigators, also, notably Flury (1912), have reported the 
occurrence in Ascaris of a number of substances toxic to experimental animals. 
Flury (1) who has made the most extensive chemical and toxicological study of 
the parasite that has yet appeared has concluded that the toxic substances of 
Ascaris include aldehydes, free fatty acids, alcohols, esters, and two nitrogenous 
substances which are not protein in nature. He did not attempt to discover the 
substance which causes the urticarial skin reaction, and apparently was not 
familiar with this phenomenon. Shimamura and Fujii (1917) by fractionation of 
the watery extract from Ascaris separated a fraction which they termed “albu- 
mose-peptone ” and to which they gave the name crude ascaron, applying the 
name ascaron to the inferred active principle, which they did not isolate (5). This 
ascaron they consider the active substance responsible for the toxicity of Ascaris, 
but their work throws little light upon the problem of the substance that causes 
the urticarial skin reaction. 
