Plants containing allergens
1. Paper mulberry (hay fever)
Broussonetia papyrifera paper mulberry is a species of flowering plant in the family Moraceae. This plant is native to Asia and is cultivated abundantly in India, China, Japan, Korea and Thailand. This is a deciduous shrub or tree usually grows 10-20 m in height. Its pollen is allergic and causes Allergic rhinitis. In Pakistan this tree is most abundant in Islamabad. This allergy caused by pollens may be seasonal or perennial.
When pollens of any plants cause allergy this is called pollinosis and if it is specifically caused by grass pollens it is called Hay fever. Theses pollens act as usual allergen and trigger the Immunoglobin E response which causes the allergy. Some other plants causing Hay fever or Allergic rhinitis are Pines, Dogwood, Red maple, Ambrosia, Rumex and many others.
Symptoms
• Sneezing
• Itchy and watery eyes, eyelid swelling, lower eyelid venous stasis (rings under the eyes known as "allergic shiners")
• Swelling and inflammation of the nasal passages
• Increase in mucus production
• Hives or other rashes in sensitive individuals
• Rhinorrhea (excess nasal secretion)
• Nasal congestion and obstruction
• Conjunctival swelling and erythema,
• Swollen nasal turbinate
• Middle ear effusion
• Asthma
Treatment
• Azelastine in eye drop form and ketotifen are used for conjunctivitis
• Intranasal corticosteroids
• Intramuscular triamcinolone acetonide injection.
2. Ragweed (eye allergy)
Ragweeds are the flowering plants of the genus Ambrosia. It is distributed in the tropical and sub-tropical regions of the world. These are annual and perennial herbs and shrubs. Its plant may grow just a few centimeters tall or maximum four meters in height.
Ragweed pollens are known for causing notorious allergies in humans like asthma, hay fever and its pollen is also known for causing eye allergy. Its pollens are carried to long distances by wind.
Mode of action
Eye allergy is called as Allergic conjunctivitis because it causes the inflammation of conjunctiva, the membrane which lines the inside of eye lids and covers the white part of the eye. If this is combined with rhinitis, the condition is termed Allergic rhinoconjunctivitis. The major allergenic compound found in the pollen has been identified as Amb a 1, a 38 kDa nonglycosylated protein which is composed of two subunits. It also contains other allergenic components, such as profilin and calcium-binding proteins. This allergen when causes the degradation of mast cells it releases the Histamine which binds to H1 receptors on nerve endings and causes the ocular symptoms of itching.
Weeping fig and various other plants contain allergens which cause Allergic conjunctivitis.
Symptoms
• Ocular itching
• Eyelid swelling
• Tearing
• Photophobia
• Watery discharge
• Foreign body sensation (with pain)
• Redness of the eye
• Edema (swelling) of the conjunctiva
Treatment
Cold compress is proven to be an effective relief. When cold compress is not effective mast cells stabilizers are used for example sodium cromoglicate. Other general treatments include injections of antihistamine drugs.
There are various other types of allergies caused by many other plants for example banana has some proteins which resemble the proteins in the sap or latex of various rubber trees so that is why banana can also caused latex- allergy similarly banana has pollens which have resemblance with the pollen proteins of ragweed so banana can also cause asthma and respiratory allergies.
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