Parthenium hysterophorus: Allergy causing plant

Parthenium hysterophorus is also known as carrot weed or Congress grass. It belong to the family of plants whose other members include sunflower and chrysanthemum. Parthenium hysterophorus is neither ornamental nor edible plant. The plant grows to the height of 3 to 5 feet and bears white flowers. The flowering starts in spring season and continues for six to seven months. The plant is found in Argentina, Brazil, Mexico, States of Texas & Minnesota of USA, West Indies, India, Pakistan and Bangladesh. Profuse growth of the plant could be seen in many cities in India. Direct contact with plant causes skin allergy to more than 50% individuals. The skin allergy caused by Parthenium hysterophorus or Congress grass may manifest as generalized eczema affecting hands, face, eyelids, neck and later arms and torso. Allergy is must in summer months but occurs all through the year. Gardeners, farmers and those engaged in outdoor activities are most affected. Young persons of either sex may also become sensitized. Abundant growth of Parthenium hysterophorus in parks, along footpaths, play grounds, roadsides and even in the lawns of houses is the main cause of parthenium dermatitis in many developed and developing countries worldwide. Long-term administration of corticosteroids may sometimes be required for controlling the symptoms of parthenium dermatitis. Affected persons with associated complications and asthma may need hospitalization. Since the cattle do not relish the plant, hence it grows unchecked. The public participation is very essential for the eradication of this environmental menace. Parthenium hysterophorus plants need to be uprooted before the flowering phase and dumped underground or destroyed with chemicals or fire to get rid of this hazardous weed.

Celiac Disease: Gluten-free diet is the treatment

The term allergy means hyper-action of our body's immune system to allergens (mostly proteins or compounds tagged to proteins). Like our skin and respiratory tract, our digestive tract (intestines) can also be hypersensitive to some constituents of food. Celiac disease is a disorder of the digestive system which is caused by intolerance/allergy to a protein called gluten. People with celiac disease can not tolerate gluten. The disease is partially genetic and inherited. Parents, siblings and children of people with celiac disease may also have/be having this disease. Celiac disease damages the inner lining of the small intestine and interferes with the absorption of nutrients from food. The cause of celiac disease is the immunological allergic reaction to gluten present in food that causes inflammation and damages the inner border (microvilli) of small intestine. Figure-1 below shows the ultrastructural changes at the inner lining of small intestine in a patient affected by Celiac disease. A visual comparison with Figure-2 (Normal inner surface of small intestine) would make you understand the pathological change.

Figure-1: Electron micrograph of biopsy from the small intestine of a patient affected by celiac disease showing eroded microvilli.

Figure-2: Electron micrograph showing normal microvilli at the inner surface of small intestine.

Sources of Gluten

Wheat, barley and rye are the main source of gluten. The gliaden component of gluten causes celiac disease. Some adhesives, medicines and vitamin products, which we use daily, may contain gluten.

Diagnostic symptoms of celiac disease

Some of the typical symptoms of celiac disease are failure to gain weight, diarrhoea, irritability, vomiting, abdominal pain and foul stools, early in infant life. The most common period of presentation and detection of celiac disease is between six months and two years of age. Some children may present with excessive appetite, abdominal distension, wasted muscle, finger clubbing and edema.

Preventive treatment of celiac disease

A gluten-free diet is the only treatment of celiac disease. A person aware of having intolerance to gluten should avoid eating foods containing wheat, barley and rye products. Modern drugs may provide symptomatic relief but ultimate treatment is preventive therapy in celiac disease.

Important Tips

1. Parents of the children with celiac disease have great responsibility to make the children comply with the doctor's instructions for gluten-free diet.


2. Recognizing and avoiding new food products containing wheat, barley or rye is a great challenge and people with celiac disease should be very careful since non-compliance of gluten-free diet may cause relapse.


3. People having celiac disease should take food items prepared from rice and corn only along with fruits, juices and milk products.


4. Reading the contents of grocery items is important before eating because many corn and rice products come from the manufacturers of wheat products.


5. Gluten-free but balanced diet is must for normal growth of the children affected by celiac disease.


6. Medicines coated/laced with gluten products should be avoided.

Chemistry of Asthma and Allergy

The allergy and asthma are very serious immunologic disorders. Everyone of us has been blessed with immune system to fight infections and respond to vaccines for acquiring active immunity. Allergens too are immunogenic but elicit hypersensitive response which could cause a local or systemic reaction like asthma. It has been learnt through animal experiments that the animals sensitized (immunized) with egg albumin react very dramatically on subsequent challenge with egg albumin. In my experience the animals have shown the symptoms of generalized anaphylaxis, respiratory distress and 50% of them died probably due to asphyxia as an intense constriction of bronchioles and bronchi was observed due to the contraction of smooth muscles. Similar reactions also occur in human subjects due a variety of conditions/causes. An injection of penicillin or an insect bite may trigger anaphylaxis in sensitive individuals. Only a timely intravenous injection of adrenaline may help in countering the smooth muscle contraction.

Mediators of Anaphylaxis or Allergic Reaction:

It was resolved by Sir Henry Dale that histamine mimics the systemic changes of anaphylaxis. Experimental studies in guinea-pigs had demonstrated that serum from sensitized animals could passively sensitize normal animals of the same species. Sir Henry Dale had demonstrated that the uterus of sensitized guinea-pig released histamine and contracted on exposure to antigen. The cells that release the mediators of anaphylaxis are the mast cells (in tissues) and basophils (in blood). The mast cells in sensitive subjects are coated by hemocytotropic antibodies of IgE class (reagins) and on interaction with the specific allergen or antigen stimulate the mast cell degranulation and release of mediators of anaphylaxis. In addition to histamine, 5-hydroxytryptamine (serotonin) is also released in some species. The contraction of smooth muscles is associated with the explosive degranulation of mast cells. Other mediators released are: slow reacting substance of anaphylaxis (SRS-A; capable of inducing prolonged contraction of certain smooth muscles), platelet activating factor (PAF), heparin and chemotactic factor for both the neutrophils and eosinophils (types of white blood cells).

Anti-anaphylaxis substances produced by Eosinophils:

The mediators of anaphylaxis released by mast cells are countered by certain substances produced by eosinophils like: histamine produced by mast cells is neutralized by histaminase, eosinophil chemotactic factor (ECF-A) is countered by aryl sulfatase and SRS-A is neutralized by phospholipase produced by eosinophils in an effort of the body to control the reaction. Systemic allergic reaction as well as percutaneous anaphylaxis leads to changes in cyclic nucleotide levels. A fall in cyclic AMP (c-AMP) and a rise in cyclic GMP (c-GMP) level, favors degranulation of mast cells, whereas high concentration of c-AMP stabilize the mast cell granules. All the anti-allergic drugs either neutralize histamine or activate c-AMP to stabilize mast cells or bind to b-2 receptors on smooth muscles to counter the smooth muscle contraction.