Birch Pollen and Allergy For Healthcare Professionals

The birch tree is a popular tree choice to plant in the street and gardens as it has an attractive silvery trunk and is a hardy fast growing medium sized tree that is relatively immune to disease and insect attack. Due to its hardy nature it is a popular choice for reforestation or to help with erosion control in areas of concern. Silver birch pollinates through catkin type structures which hang from the branches. The pollen is very light and fine in structure and is wind pollinated.  The pollen can be carried great distances, therefore you do not need to be in an area populated by trees to feel the effects of tree pollens.

Birch pollen and allergy

Birch pollen allergy is thought to affect approx. 25% of hay fever sufferers, Birch pollen is highly allergenic and one of the most potent allergens, triggering not only allergic rhinitis and allergic conjunctivitis symptoms, but also Pollen food syndrome (i.e. allergies to certain plant based foods). The majority of sufferers will experience allergic rhinitis symptoms during the peak pollen season – March – April, however symptoms can occur earlier, sometimes as early as around January, due to the cross reactivity between Birch pollen and other tree pollens including Alder and Hazel which pollinates earlier. It must be noted there are a significant number of individuals that will be sensitised to both tree and grass pollens and will experience symptoms for much of the spring and summer months.

Pollen calendar and pollen forecast

The pollen calendar is a useful tool to chart when common trees, grasses and weeds will pollinate and so likely to trigger symptoms. It can be a useful tool to use to spot pollen seasons and decide when to start or increase medication to help reduce symptoms.

Worcester pollen count

The University of Worcester has a useful webpage that gives a daily pollen forecast for the UK. Useful Apps to track pollen forecast include Allergy Alert App and My Pollen Forecast UK.

Click here to view Worcester pollen count

Did you know...

  • 25%

    of adults in the UK

    are affected by allergic rhinitis

  • 10-15%

    of children in the UK

    are affected by allergic rhinitis

Seasonal Allergic Rhinitis

Allergic rhinitis is an immunoglobulin E (IgE)-mediated inflammatory response in the nasal lining to a trigger allergen in a sensitised individual and is a common inflammatory condition of the upper respiratory tract.

Allergic rhinitis affects approx. 25% of adults and 10 -15% of children in UK, and is increasing in prevalence, with a significant impact of quality of life for sufferers. ARIA classifies allergic rhinitis as moderate to severe when one or more of the following are impacted; sleep disturbance, impairment of daily activities, and impairment of school/work.

Symptoms, include; itching of the nose, sneezing, rhinorrhoea, sneezing, and nasal congestion. Frequently, there is associated palate, throat, ear, and eye itching as well as eye redness, puffiness, and watery discharge. Cough is also a common symptom and wheeze or difficulty breathing can also occur if the patient has allergic asthma.

Diagnosis is usually confirmed through the patient history, without the need for diagnostic testing, however skin prick test or specific IgE blood test or component testing is useful to determine whether the rhinitis is driven by allergy, or where the trigger allergen is not obvious or if exact identification of the allergen is needed for diagnosis or specialist treatments e.g. immunotherapy. Identification of the allergen is needed for diagnosis or specialist treatments e.g. immunotherapy.

Treatment options include allergen avoidance, reducing exposure to the relevant allergens, nasal douching, pharmacotherapy including non-sedating antihistamines, intranasal corticosteroids, leukotriene receptor antagonist and immunotherapy. With intranasal corticosteroids currently the single most effective class of medications for treating allergic rhinitis. However Immunotherapy is often recommended for patients with persistent symptoms, especially if they impact on their daily activities.

Immunotherapy

Allergen immunotherapy involves the repeated administration of allergen extracts with the aim of reducing symptoms on subsequent allergen exposure, improving quality of life and inducing long term tolerance (Walker et al 2011)

Allergen immunotherapy works by inducing immunological tolerance through a gradual reduction in IgE-mediated responses [Ellis 2019). In the allergic response the body activates a TH2 immune response to trigger an immunological process involving activation of lymphocytes IL-13 and IL-4, T cell and B cell production to trigger the mast cell to degranulate and release histamine causing vasodilation and vascular permeability and development of allergic symptoms including increase in mucus production and constriction of the airways.

Immunotherapy works by increasing allergen specific lymphocytes such as T regulatory cells and IL-10 which modulates the production of IL-4 and inhibits the production of IgE mast cell activation, also inducing a immunological deviation from TH2 response to TH1 by increase IFN-y and suppression of IL-5 and eosinophil production and thereby inhibiting the allergic response, these changes to the immune system contribute to lasting tolerance.

There are two methods for administration of immunotherapy SLIT – Sublingual immunotherapy given as drops or tablet form and SCIT – Sub cutaneous immunotherapy given via injection by a trained clinician, the timing of this injectable method varies depending on where they are in administration schedule i.e., up dosing or maintenance.  Immunotherapy has been found to not only improve symptoms of allergic rhinitis, but also improve asthma symptoms and reduce asthma medication use in in individuals with concurrent allergic rhinitis. Immunotherapy may also prevent new allergic sensitisations and the development of asthma.

Management considerations

  • Treating symptoms of allergic rhinitis (AR) can improve management of asthma symptoms
  • It is important to make sure hay fever, symptoms are treated adequately, to prevent asthma developing, especially in children
  • It is important to also treat symptoms of allergic rhinoconjuntivitis (ARC)
  • AR and ARC has a significant negative impact on many children and adults
  • Observe for signs of poorly managed allergic rhinitis such as mouth breathing
  • As well as pharmacotherapy consider – Nasal allergen barrier balms and nasal douching. These can be used as frequently as required and in conjunction with usual medication.
  • Intranasal steroids can help with asthma control
  • If insufficient response to optimised medical treatment consider referral for allergen immunotherapy
  • Immunotherapy for allergic rhinitis is not only a very successful treatment for severe allergic rhinitis but may prevent asthma developing.

Consider differential diagnosis and refer to ENT if:

  • Unilateral symptoms only
  • Anosmia
  • Pain, pus, bleeding.

Allergic Conjunctivitis

Allergic eye disease is a very common symptom associated with allergic rhinitis.

Symptoms include itching, burning, watering and redness of the eye, and puffiness of the eyelids.

The part of the eye that is visible is not the area mainly affected. The cornea (the transparent window of the eye which lies over the coloured iris) is not affected at all, and the surrounding ‘white of the eye’ is only slightly affected. The part that is not seen directly, a relatively large area that lies beneath the eyelids, is where the reaction mainly takes place.

What is seen under the upper eyelid in allergic conjunctivitis is slight redness (hyperaemia), slight swelling (oedema) of the tissues, and sometimes a little bumpiness (papillary hyperplasia). This lack of major signs, coupled with the typical seasonal history and symptoms, is what helps to distinguish allergic conjunctivitis from other causes of conjunctivitis/inflammation such as infection.

Management of allergic eye disease

  • Allergen avoidance, before allergens can be avoided they must be identified. In many cases the likely triggers can be identified by taking a careful history from the patient. Many allergic people react to common allergens, which are difficult to avoid.
  • Anti-histamine eye drops can be helpful.
  • Oral antihistamines suit many patients whose eye symptoms coincide with other symptoms of hay fever. Long acting, non-sedating oral antihistamines are recommended for regular use.
  • Mast cell stabilisers are preparations can also include antihistamine properties and are very useful in the management of allergic eye disease.
  • Steroid eye preparations are very effective in allergic eye disease but their unwanted effects can be severe and even sight-threatening.
  • Non-steroidal anti-inflammatory drugs (NSAIDs) are available in eye drop form, but their place in the management of allergic eye disease is not fully determined.
  • Immunosuppressive agents are used in the management of VKC and AKC under the guidance of an ophthalmologist. Ciclosporin is one of these, and its beneficial effects have been known for some years. It is licensed for use in severe VKC in children from the age of four years to adolescence.
  • Immunotherapy may help a small number of people whose allergic eye disease is caused by a single allergen, rather than by a number of allergens. By giving very small doses of the allergen at regular intervals for three years or more, either by injection into the skin or by tablets held under the tongue, the body can be desensitized.
  • Holistic supportive measures can be very helpful in controlling the symptoms of allergic eye disease. These include cold compresses and artificial tear preparations. Wraparound sunglasses in the pollen season may also be helpful.

Management considerations

  • Manage any allergic rhinitis symptoms adequately
  • Advise on avoidance of allergens where practicable
  • Consider referral for severe symptoms or symptoms not responding to standard treatments.

Red flags

  • Vernal keratoconjunctivitis (VKC), occurs in some severely allergic children. It seems to be more prevalent in boys and also in those children with severe atopic dermatitis .
  • Atopic keratoconjunctivitis (AKC) occurs in adults.

In both of these conditions the cornea is usually involved, affecting and can even threaten the sight of the eye.

Some contact lens wearers suffer from a condition called giant papillary conjunctivitis (GPC), which is similar to VKC and AKC, but does not involve the cornea.

Did you know...

  • 2%

    of adults

    are affected by Pollen Food Syndrome

  • up to 50%

    of patients with IBS

    may have Pollen Food Syndrome

  • 25%

    of individuals with eosinophilic esophagitis

    may have Pollen Food Syndrome

Pollen Food Syndrome

Birch pollen typically causes allergic rhinitis symptoms in the nose and eyes, but can also cause symptoms in the oral /pharyngeal mucosa referred to as Pollen Food Syndrome or oral allergy syndrome.

Pollen food syndrome (PFS), also known as oral allergy syndrome, is a hypersensitivity reaction to plant foods – e.g. fruit  vegetables and nuts usually causing symptoms in the oral / pharyngeal mucosa, triggered by a cross reactivity between allergens in pollen and allergens in fresh fruit or vegetable.

Sensitisation occurs after exposure via the lungs triggers a cross reactivity between allergens in tree or occasionally grass and weed pollens and allergens in plant foods eg fresh fruits, vegetable and nuts due to the similarity in structure of the allergen. The most common cause of food pollen syndrome is sensitisation to Birch pollen (Betv1) which has similar structure to many fruits, vegetable or nuts.

Who does Pollen food syndrome (PFS) affect ?

  • PFS Affects approx. 2% of the adult population and is the main cause of food allergic reactions in adults
  • Note PFS can also affect children – especially atopic children with a history of hay fever or pollen sensitivity to grass/ tree pollens
  • More common with poly sensitisation to multiple pollens
  • More common in individuals with symptomatic seasonal allergic rhinitis (SAR) but many PFS suffers many not exhibit symptoms of SAR

Symptoms

Symptoms are usually mild and can include a history of immediate-onset;

  • Mild to moderate mild swelling or itching of the lips, tongue, inside of the mouth, soft palate and ears, itching and mild swelling affecting the throat.
  • Occasionally, symptoms in the oesophagus (gullet) or stomach, causing abdominal pain, nausea and even vomiting
  • Sometimes sneezing, runny nose, or eye symptoms can also occur.
  • This is most often to raw fruits and nuts, especially apples, stone fruits, kiwifruit, hazelnuts, almonds walnuts and peanuts. Whilst cooked fruits and vegetables are usually tolerated as are nuts in foods.
  • Caution – concentrated amounts of allergen such as freshly made fruit juices, smoothies, or soy milk, which contains the birch cross-reacting allergen Gly m 4, can cause severe reactions.

Diagnosis and testing

  • A meticulous clinical history can often detect PFS without need for further testing
  • Skin prick testing is the most common diagnostic method used for detection of PFS
  • Tests may be needed if nuts are involved, to discriminate between a diagnosis of PFS or a primary allergy to nuts/soy.

Management considerations

  • Manage any hay fever/ asthma symptoms adequately to prevent more severe allergic reactions
  • Avoidance of foods causing allergic reactions, often cooked fruits and vegetables are usually tolerated.
  • Need to be aware of potential for nutritional deficiency / vitamin supplements
  • May need to consider referral to a dietician, if individuals are avoiding large numbers of fruits, vegetables, nuts and cereal based food in their diet
  • Management of anxiety surrounding possible reactions and severity of future reactions
  • AAIs are only required in a diagnosis of severe systemic allergic reaction / anaphylaxis to plant foods which is very rare
  • Individuals with comorbidities including IBS (irritable bowel syndrome) and EOS (eosinophilic esophagitis) may be at increased risk of developing food pollen syndrome especially if they have seasonal allergic rhinitis (SAR)

Guidelines

There are various guidelines available for the treatment and management of allergic rhinitis including immunotherapy, allergic eye disease and pollen food syndrome (oral allergy syndrome)

Guidelines for Allergic Rhinitis

Nice Guidelines: Clinical knowledge summaries – Allergic Rhinitis – Management in primary care

BSACI guidelines: Diagnosis and management of allergic rhinitis

BSACI guidelines: Immunotherapy for Allergic Rhinitis

EAACI guidelines: Allergic Rhinitis Quick Overview

ARIA guidelines: Allergic Rhinitis and impact on Asthma Guidelines 2020

Guidelines for allergic eye disease

NICE Clinical Knowledge summaries: Conjunctivitis Allergic 

Guidelines for pollen food syndrome and lipid transfer proteins

BSACI guidelines: Pollen food syndrome (oral allergy syndrome) is awaiting final approvals, will be available soon

BSACI guidelines: Peanut and tree nut allergy guideline 2017

Clinical knowledge summary: When should I suspect food allergy 2018 (section on oral allergy syndrome)

Patient information 

How to

Useful patient websites

Apps

  • Mask Air – Allergic rhinitis symptoms
  • Pollen forecast – Allergy Alert App and My Pollen Forecast UK

This content has been developed by the Allergy UK clinical team and this page is supported by Thermo Fisher Scientific

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