Hey, you got the fever?

Always one to sniff out a good story, this week Stuart let us in on the facts behind plant pollen allergies and hay fever, otherwise known as allergic rhinitis. Not to mention the horror that is rhinorrhea (that’s actually just the technical term for a runny nose, but it sounds pretty horrific).

Not all plant pollen causes allergic reactions, only that carried by the wind, which usually means you don't even notice the flowers. Shape is often an indicator of how pollen is spread. This pollen is magnified under an electron microscope by about 500x actual size (Photo from Dartmouth Electron Microscope Facility)

Although there’s a tendency to blame wattles and other showy flowers for our pain, those are unlikely to be responsible because they’re pollinated by insects. It’s much more likely to be due to the less obvious, wind-pollinated plants like grasses, that cast their pollen on the air.

To find out which plants cause hay fever and what time of year to avoid them, see the Australian Society of Clinical Immunology and Allergy’s Guide to common allergic pollen.

And for further information on hay fever symptoms and treatment options, check out the Better Health Channel.

Full story from the show:

Allergic rhinitis, commonly known as hay fever, affects 1 in 5 Australians, it can be classified as either perennial, which is continuous; or seasonal, which is affected by other factors, primarily the occurrence of the allergen i.e. the factor that prompts the allergic reaction.

Aside from the obvious immediate symptoms, allergic rhinitis predisposes people to more frequent sinus infections, and those susceptible can get tired and run down due to poor quality sleep. Severe allergic rhinitis impairs learning and performance in children, and results in more frequent absenteeism in adults and reduced productivity. It also makes asthma more difficult to control, as well as pollen being able to directly trigger asthmatic responses in certain cases.

Certain other disorders are correlated with hayfever, though the relationships are not clear. These can include

  • eczema
  • asthma
  • depression
  • migraine

Commonly known as “hay fever”, because it used to be most prevalent during hay cutting season. But it can strike any time of year. The actual pollen which triggers the reaction varies between individuals and from region to region;

Generally speaking, wind-pollinated plants are the predominant cause. Pollens of insect-pollinated plants, usually from colourful, showy flowers, are too large to remain airborne and pose no risk.

Northern Hemisphere grass, tree and weed pollen cause the most problems. Pollen from exotic trees, which are planted for their autumn colours, is more allergenic than pollen from Australian trees.

Improved pasture grasses are more allergenic than Australian native grasses.

  • Grasses (Family Poaceae): especially ryegrass (Lolium sp.) and timothy (Phleum pratense). An estimated 90% of hay fever sufferers are allergic to grass pollen.

A number of weeds with highly allergenic pollen have also been introduced, including:

  • Weeds: ragweed (Ambrosia), plantain (Plantago), nettle/parietaria (Urticaceae), mugwort (Artemisia), Fat hen (Chenopodium) and sorrel/dock (Rumex)
  • Paterson’s Curse (Echium plantagineum) is an attractive flowering plant that was deliberately brought from England in the late 1800’s by Dr Paterson. This plant has taken over large tracts of pasture in rural Australia and produces highly allergenic pollen.
  • Ragweed and Parthenium weed were introduced in pasture seed imported from the United States. They have spread throughout Queensland and northern New South Wales.

Because flowering is directly affected by factors such as temperature and rainfall, changes in the climate could result in longer pollen seasons, or shifted seasons, as well as the proliferation of allergy causing plants which may not be present in certain areas, or only present currently in small numbers. This could worsen the symptoms in susceptible people, and affect people not currently affected by airborne allergens.

[Allergic disease–pollen allergy and climate change]. 2009 Author: Sommer, Janne Add.Author / Editor: Plaschke, Peter ; Poulsen, Lars K

[The effect of climate change on pollen allergy in the Netherlands].  Author: de Weger, Letty A Add.Author / Editor: Hiemstra, Pieter S Citation: Ned Tijdschr Geneeskd Volume: 153, Date: 2009 , Pages: A1410 Year: 2009

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