ASCARIS SENSITIZATION 1 
B. H. Ransom, U. S . Bureau of Animal Industry; W. T. Harrison, Hygienic 
Laboratory f U . S . Public Health Service; and J. F. Couch, U . $. Bureau of 
Animal Industry 
It is a well established fact that Ascaris lumbricoides , the common intestinal 
roundworm of human beings and pigs, and other more or less closely related 
species parasitic in various animals, have toxic properties. This is clear not 
only from the nature of the symptoms in many cases of infestation which can be 
explained only on the basis of a toxic origin but also from the experience of 
many persons, mostly laboratory workers, who have had occasion to handle 
these parasites or who have in some way been brought into contact with them. 
Zoologists, for example, who have made extensive use of the horse Ascaris in 
cytological studies, have been frequent sufferers from its poisonous effects,* 
Goldschmidt (1910) who was himself susceptible discovered by inquiry among 
zoologists of his acquaintance about 20 cases of similar susceptibility. (2) ? 
Prior to Goldschmidt various writers, Bastian, Huber, Railliet, Linstow, and 
others, had reported personal experiences with the toxic effects of Ascaris, in¬ 
volving either the horse Ascaris or the human Ascaris. In fact susceptibility 
to Ascaris toxins is a very common condition among biologists who have been 
much exposed to contact with the parasite. Thus Ascaris sensitization is a sort 
of occupational disease. Its significance in relation to the toxic action of Ascaris 
in cases of infestation with the parasite remains to be determined. 
The symptoms in persons who are sensitive to contact with Ascaris are of a 
kind that immediately suggest a similarity to the symptoms seen in cases of 
hay fever, asthma and other conditions grouped under the heading of foreign 
protein sensitization. Among the symptoms are irritation of the mucous mem¬ 
branes of the eyes, nose, and throat, lacrimation and edema of the eyes, facial 
edema, sneezing, coughing, swelling of the nasal mucosa, increased nasal and 
bronchial secretions, painful deglutition, urticaria, asthma, headache, fever, 
pruritus, tingling and burning sensations, swelling of the fingers, lassitude and 
weakness, sometimes amounting to prostration. In some cases the asthmatic 
attacks have persisted for weeks after exposure, but it is not certain in these 
cases that the possibility of subsequent exposures was entirely excluded. It 
has been commonly stated that the offending substance or substances are given 
off as emanations by the worm and thus are presumably volatile, but that they 
are actually volatile in the usual sense of the word has not been finally proved, 
although Weinberg and Julien ( 8 ) obtained a positive ophthalmic reaction in 
one out of 25 horses tested with the products of distillation of the body-cavity 
fluid of the horse ascarid, a result tending to support the prevalent belief in the 
presence of volatile substances in Ascaris that will produce symptoms in sensitive 
persons. Our own investigations thus far have failed to demonstrate a volatile 
substance that causes symptoms in human subjects sensitive to Ascaris, but we 
have not yet in our work taken up the question of those fractions of the worm 
that are insoluble in water. 
1 Received for publication May 12, 1924. 
2 Reference is made by number (italic) to “ Literature cited,’’ p. 582. 
Journal of Agricultural Research, 
Washington, D. C. 
( 577 ) 
Vol. XXVIII, No. 0 
May 10,1924 
Key No. A-74 
