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| By A. H.
Redmon, Jr., M.D. |
Each fall,
Houston and the entire Texas Gulf Coast are inundated by staggering amounts of
airborne microscopic (1-3 microns) pollen grains of the ragweed-marsh elder
family of weeds during its reproductive season, or "Fall Hay Fever Season", and
the "misery index" for those allergic to these pollens increases dramatically.
In Houston, the season usually begins about the middle of September and lasts
into November, but, as one goes northward, the season may begin in August and
end by October.
"Hay Fever" is a misnomer for Seasonal Allergic Rhinitis. The
severe and even debilitating symptoms of sneezing, head and nasal congestion,
itching, eye watering, asthma, and even hives have no relation to hay. Years
ago these symptoms were associated with the haying season in late summer or
fall, thus "Hay Fever". Goldenrod (genus Solidago) was blamed because during
this time its colorful flowers were easily visible while the real culprits, the
ragweeds, were not. They were quietly and without attractive and visible blooms
producing pollen and causing all the trouble.
These herbaceous weeds called
"ragweeds" are just a few of one of the largest family of flowering plants of
the Compositae or Asteraceae family which contains some 25,000 species divided
into twelve major tribes. Asters, daisies, zinnias, chrysanthemums, sunflowers,
thistle, chicory, sages, and food plants such as lettuce and artichokes are
included. Pyrethrum, an insecticide, is derived from a plant of this family and
may cause allergic symptoms upon exposure to anyone allergic to the
ragweed-marsh elder pollens.
Three main groups of these weeds produce most of the
pollen. 1) Ambrosieae includes the various ragweeds. 2) Ivenea includes the
marsh elders and prairie ragweed. 3) Artemisia includes the sage family.
Reference to ragweed must include all the related allergenic groups. These are
mostly annual plants that germinate from seed, grow, and flower, producing
prodigious amounts of pollen for reproduction and seed formation. They then die
naturally or may be killed by cold weather or a frost.
They range from the small or dwarf ragweed, a few
inches high, to the giant or western ragweed, 18 to 20 feet tall. They thrive
from the Eastern Seaboard to the Rockies, are less abundant west of the
Rockies, and are particularly abundant along the flat Texas Gulf Coast causing
some of the highest pollen counts recorded. They grow along fencerows,
irrigation and drainage ditches, uncultivated fields, bayous, and the edges of
wooded areas. There are massive stands of these plants in Downtown Houston and
even in the Texas Medical Center. Almost every un-mowed lot or tract will
contain thousands of these plants.
All are anemophilous, requiring and depending upon wind and air
currents to transfer the somewhat lighter-than-air pollen grains (the male
genetic material) from the anthers of one bloom to the pistil or ovary of
another bloom for pollination. Because this method of procreation is chancy or
haphazard depending on a single pollen grain floating in air and landing on an
appropriate receptive pistil, a tremendous amount of pollen must be produced,
and is. The Guinness Book of Records states that one ragweed plant can produce
eight billion pollen grains in five hours. Pollens travel hundreds of miles
with cold fronts and may be found in the atmosphere as high as 12,000
feet.
Pollen
content of the air varies with atmospheric conditions and will be extremely
high on bright, clear, cool, and breezy days in October in the Gulf Coast area
and lower with rain and damp weather. High concentrations of pollen are
released in the early morning and again toward evening. Hazy clouds of pollen
can be seen in areas with masses of plants. Pollen count reports are for the
previous 24-hours and may change over night.
There is no such thing as a "sneezing point". One
sensitive sufferer's "sneezing point" might be 10 grains per cubic yard, while
another may tolerate over l,000 grains per cubic yard. As the season
progresses, a sensitive individual becomes even more sensitive and will react
to a smaller number of pollen grains.
Ragweed pollens are not the only airborne allergens
during the fall. Mold spores, house dust and house dust mites and other pollens
including grasses and some trees may add to the misery in a sensitive
individual.
Several years ago I was involved in a research study with the
Allergy and Immunology Department of Washington University Medical School and
found that another plant; Parthenium hysterophorus (Santa Maria Fever Few) may
also cause allergic rhinitis in the fall.
What does all of this mean and what difference does
it all make? Well, for an individual who is allergic to these pollens, it makes
a lot of difference with severe and even disabling symptoms during the
fall.
The answer
to the question "Why me?" involves the immune system and its production of
antibodies to the pollens of the ragweed family. These antibodies sensitize
mucous membranes of the eyes, nose, sinuses, lungs, skin, etc. and subsequent
exposure results in a reaction. The pollen grain lands on sensitized mucous
membranes and a protein substance from the pollen is absorbed through the
membrane. This substance combines with the antibody resulting in the release of
chemical mediators, i.e., histamine, which cause the
symptoms.
What
can "Fall Hay Fever" sufferers do?
1. Go to a ragweed-free area west of the Rockies,
Hawaii, Europe, etc. or to the northern U.S.A. after the season is finished
there.
2. Stay in
air-conditioned/filtered air and refrain from "airing out the house" during a
nice, cool, crisp, day in October.
3. Take long-acting antihistamines, regularly, daily, and,
preferably, prior to the onset of symptoms. Many are available without a
prescription.
4.
See a physician who can prescribe newer and very effective medications
including corticosteroids orally, by injection or also by nasal
spray.
5. Receive
immunotherapy or desensitization injections under the care of a Board Certified
Allergist.
6.
Encourage cities, counties and landowners to keep unused or uncultivated areas
mowed.
It is
interesting to consider that this allergic problem occurs because humans
intrude inadvertently in a plant's process of transferring pollens from an
anther to a receptive pistil/ovary of the same species.
Could it be that "Hay Fever" is a
plant's revenge for interfering in its reproductive
process?
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