House dust mites

Pollen which appear at unusual times of the annual cycle:
Usually the pollen season starts in spring and ends in late summer / autumn. Some plants however, flower late in the year and release nonetheless considerable amounts of pollen.

Cedars flower in late September / early October and may cause conspicuous yellowish precipitations similar to what we know from pine and spruce in certain years during May.

Ivy pollen becomes airborne in small amounts at about the same time.

different species of the cypress family may flower throughout the year and release some pollen. In the Mediterranean, cypress is sometimes already in December in full flower.

In late autumn one can notice in some years a yellowish dust layer here and there, composed of rust summer spores of Puccinia (black rust or stem rust on wheat).

long - distance pollen transport

During winter time, sand from the Sahara desert is transported by strong winds far north to Europe. We sometimes detect at such occasions very characteristic pollen grains from Ephedra, which flowers in late winter in the Atlas mountains.

In particular in Scandinavia, birch pollen allergic patients must often face surprising hayfever attacks in early spring although no birch is yet flowering far and wide. Long distance transport can deposit lots of birch pollen of southern origin by suitable weather conditions. Ambitious forcast models are under development, combining methods of meteorology, aerobiology and remot satellite sensing.

Reference information: www.aaaai.org, www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above. 

藥物過敏治療 Allergen Immunotherapy in Hong Kong

Allergic diseases such as allergic rhinitis (nasal allergy), allergic conjunctivitis (ocular allergy) and asthma are chronic diseases.  These diseases are caused by the immune system reacting inappropriately to normally harmless substances such as pollens, dust mites, mold spores and animal dander.  While there are drugs such as steroids and antihistamines that can effectively control the symptoms, the only option for eliminating the root cause of the problem remains allergen immunotherapy (also called desensitization, hyposensitization or allergy shots).

Allergen extracts are prepared according to the sensitivities of the individual.  The extracts are administered at regular intervals to induce a response called immune tolerance.  The tolerance response is achieved by the production of blocking antibodies and regulatory T cells.  When this happens, the patient’s sensitivity to the allergens progressively diminishes, and symptoms also decline.  Studies have shown that after three to five years of treatment, the effectiveness persists long-term even after treatment is discontinued.

Allergic rhinitis in childhood is a risk factor for the development of asthma.  A study shows that children who received allergen immunotherapy for allergic rhinitis have 2.5-fold reduced risk of developing asthma.  This effect is still evident 10 years after treatment.

Recent studies have also shown that for a subset of patients with atopic dermatitis, where environmental allergy is a major factor in their illness, immunotherapy is effective in reducing the severity of their skin disease.

Allergen immunotherapy has traditionally been administered by subcutaneous injections. Newer forms of treatment such as sublingual immunotherapy have been developed that are more convenient, and maybe suitable for selected patients

Reference information: http://www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.