The Encyclopedia Americana (1920)/Hay fever
HAY FEVER, a nervous affection of the
mucous membranes of the eyes, nose, mouth,
pharynx, larynx, and bronchi, characterized by a
profuse flow of secretion from the nose, and of
tears from the eyes, and accompanied in some
eases by asthma. It is induced by the lodgment
on the mucous membranes of the eye, nose and
throat of the wind-borne pollen of certain
plants. The disease varies in its severity
according to certain atmospheric conditions and
the amount of pollen in the air. Occurring at
the haying season the disease received its title
through that association. The prevalence of

catarrhal symptoms in summer separates it
from an ordinary “cold in the head”; while their
combination with difficulty of breathing
prevents it being mistaken for spasmodic asthma,
in which there is seldom any catarrh. There
are three combining causes of this affection,
which is largely nervous: First, a predisposing
cause in some nervous disease, with a probable
lesion in the fourth ventricle of the brain.
Second, deformity, such as a deviating septum,
in the nasal region. Third, inhalation of a
special pollen. Removal to the seashore or the
mountains is beneficial in most cases, and a sea
voyage, or other complete removal from pollen
afflicted regions brings entire release. The
succinimide of mercury affords relief in many
cases, and arsenic, iodides, bromides, and other
nerve specifics benefit others. For the asthma,
iodide of potash, 5 grains with 5 minims of
tincture of belladonna in syrup of orange-peel
should be taken every two hours. Calcium
chloride is also very effective where asthmatic
symptoms are marked. Inhalations of nitre-paper,
stramonium leaves, etc., with wine of
coca internally, are also useful.

These remedies are, however, merely palliatives,
and scientific men have been for some time
making investigations which may eventually
lead to the discovery of a radical cure.

Professor Dunbar, of Hamburg, who has
been studying the subject for seven years, is
one of those who hold out the hope for curing
hay fever by a rational treatment.

According to him, the disease is caused by
the pollen of grasses, but not by mechanical
irritation. He has extracted from the pollen
a protein poison, or toxin, which is insoluble
in ether and alcohol, but soluble in water and
weak saline solutions, tears, the mucus of the
nose and the serum of blood. A solution of
this toxin dropped into the eye or nose at once
produces the characteristic symptoms of hay
fever. The same symptoms in an aggravated
form occur when the solution is injected
hypodermically.

This discovery suggested treatment by the
serum method and Dr. Dunbar set to work to
produce a curative serum by inoculating animals
with pollen toxin, and a serum was eventually
obtained which, when dropped into the eye or
nose together with pollen toxin, completely
prevented the attack which the latter alone would
have caused. In practical use, however, both
the serum and the vaccination treatments have
failed, and it is now generally admitted that the
only completely effective treatment is avoidance
of the cause.

Recent investigations have established the
fact that hay fever is a distinctly preventable
disease. Where there is none of the poisonous
pollen the disease does not exist. The fact
of prime importance is that only wind-borne
pollen produces the disease. The pollen of
golden rod, daisies, dandelions, and sunflowers
will produce the symptoms if directly inhaled,
but at a little distance such plants are harmless:
their pollen is too heavy to be carried by the
wind. On the other hand it has been found
that some pollen travels several miles on the
wind, but the farther it goes the more widely
it is scattered, and it is rarely in sufficient
quantity to produce the disease beyond half a
mile from its source. Another established
fact of importance is that immunity from the

disease does not imply that the immune person
is not inhaling pollen, but simply that he is not
inhaling more than his system can resist. It
is only when the pernicious toxin of the pollen
is assimilated beyond the capacity of resistance
that the symptoms appear. After an attack is
definitely begun, a much smaller addition of the
toxin is sufficient to keep it going. The very
wide degree of personal resistance to the pollen
toxin explains the susceptibility of some persons
and the immunity of others breathing the same
pollen and in the same quantities. Unfortunately
an attack of the disease leaves the patient
more susceptible than before. Curiously,
however, farm workers who are continually breathing
pollen do not have hay fever.

The earlier summer cases of hay fever are
attributed to the pollen of several of the
grasses and to that of the yellow dock (rumex
crispus). The midsummer cases are said to be
due to “careless weed” (amaranthus spinosus)
and cocklebur (xanthium Canadense). The
much larger proportion of cases of the early
autumn are unquestionably due to the pollen of
the ragweeds ambrosia trifida and ambrosia
elatior. The marsh elder (iva ciliata) is also
credited with a share in the scourge. The
official experiment of cutting the ragweeds in and
about New Orleans in the summer of 1915
resulted in shortening the “season” of hay fever
in that city by several weeks. The output of
pollen was so reduced within a half-mile
distance from the city as to render it innocuous
except to the most susceptible, and these eventually
escaped by temporary removal to the centre
of the city, beyond the reach of the pollen-laden
winds.