Urticaria (or hives) are a kind of skin rash notable for dark red, raised, itchy bumps. Hives are frequently caused by allergic reactions, however there are many non-allergic causes. For example, most cases of hives lasting less than 6 weeks (acute urticaria) are the result of an allergic trigger. Chronic urticaria (hives lasting longer than 6 weeks) are rarely due to an allergy. The majority of patients with chronic hives have an unknown (idiopathic) cause. Perhaps as many as 30-40% of patients with chronic idiopathic urticaria will, in fact, have an autoimmune cause. Acute viral infection is another common cause of acute urticaria (viral exanthem). Less common causes of hives include friction, pressure, temperature extremes, exercise, and sunlight. It may be true that hives are more common in those with fair skin.
Angioedema is a related condition and if you would like to read further on Urticaria, the following link is a good read.
Hives also known as Urticaria
Angioedema
Angioedema
Is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. In short it is the swelling of the throat.
In the past, angioedema was referred to by the term angioneurotic edema, which wrongly implied that the phenomenon was due to neurosis.
Cases where angioedema progresses rapidly should be treated as a medical emergency as airway obstruction and suffocation can occur. Epinephrine may be lifesaving when the cause of angioedema is allergic. In the case of hereditary angioedema, treatment with epinephrine has not been shown to be helpful.
For more indepth knowledge of Angioedema please use the following link.
Sinusitis
Sinusitis is an inflammation of the paranasal sinuses, which may or may not be as a result of infection, from bacterial, fungal, viral, allergic or autoimmune issues. Newer classifications of sinusitis refer to it as rhinosinusitis, taking into account the thought that inflammation of the sinuses cannot occur without some inflammation of the nose as well (rhinitis).
By location
There are several paired paranasal sinuses, including the frontal, ethmoid, maxillary and sphenoid sinuses. The ethmoid sinuses can also be further broken down into anterior and posterior, the division of which is defined as the basal lamella of the middle turbinate. In addition to the acuity of disease, discussed below, sinusitis can be classified by the sinus cavity which it affects:
- Maxillary sinusitis - can cause pain or pressure in the maxillary (cheek) area (e.g., toothache, headache)
- Frontal sinusitis - can cause pain or pressure in the frontal sinus cavity (located behind/above eyes), headache
- Ethmoid sinusitis - can cause pain or pressure pain between/behind eyes, headache
- Sphenoid sinusitis - can cause pain or pressure behind the eyes, but often refers to the vertex of the head
Recent theories of sinusitis indicate that it often occurs as part of a spectrum of diseases that affect the respiratory tract (i.e., the "one airway" theory) and is often linked to asthma. All forms of sinusitis may either result in, or be a part of, a generalized inflammation of the airway so other airway symptoms such as cough may be associated with it.
By duration
Sinusitis can be acute (going on less than four weeks), subacute (4-12 weeks) or chronic (going on for 12 weeks or more). All three types of sinusitis have similar symptoms, and are thus often difficult to distinguish.
Allergic Conjunctivitis
Allergic conjunctivitis is inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Although allergens differ between patients, the most common cause is hay fever. Symptoms consist of redness (mainly due to vasodilation of the peripheral small blood vessels), oedema of the conjunctiva, itching and increased lacrimation (production of tears). If this is combined with rhinitis, the condition is termed allergic rhinoconjunctivitis.
The symptoms are due to release of histamine and other active substances by mast cells, which stimulate dilation of blood vessels, irritate nerve endings and increase secretion of tears.
Treatment of allergic conjunctivitis is by avoiding the allergen (e.g. avoiding grass in bloom during the "hay fever season") and treatment with antihistamines, either topical (in the form of eye drops), or systemic (in the form of tablets). Cromoglicate is sometimes used topically.
Hygeine Hypothesis
Hygiene Hypothesis
According to the hygiene hypothesis, proposed by David P. Strachan, allergic diseases are caused by inappropriate immunological responses to harmless antigens driven by a TH2-mediated immune response. Many bacteria and viruses elicit a TH1-mediated immune response, which down-regulates TH2 responses. The first proposed mechanism of action of the hygiene hypothesis stated that insufficient stimulation of the TH1 arm of the immune system lead to an overactive TH2 arm, which in turn led to allergic disease. In other words, individuals living in too sterile an environment are not exposed to enough pathogens to keep the immune system busy. Since our bodies evolved to deal with a certain level of such pathogens, when it is not exposed to this level the immune system will attack harmless antigens, and thus normally benign microbial objects, like pollen, will trigger an immune response.
The hygiene hypothesis was developed to explain the observation that hay fever and eczema, both allergic diseases, were less common in children from larger families, which were presumably exposed to more infectious agents through their siblings, than in children from families with only one child. The hygiene hypothesis has been extensively investigated by immunologists and epidemiologists and has become an important theoretical framework for the study of allergic disorders. It is used to explain the increase in allergic diseases that has been seen since industrialization, and the higher incidence of allergic diseases in more developed countries. The hygiene hypothesis has now expanded to include exposure to symbiotic bacteria and parasites as important modulators of immune system development, along with infectious agents.
Epidemiological data supports the hygiene hypothesis. Studies have shown that various immunological and autoimmune diseases are much less common in the developing world than the industrialized world and that immigrants to the industrialized world from the developing world increasingly develop immunological disorders in relation to the length of time since arrival in the industrialized world. Longitudinal studies in the third world demonstrate an increase in immunological disorders as a country grows more affluent and, presumably, cleaner. The use of antibiotics in the first year of life has been linked to asthma and other allergic diseases. The use of antibacterial cleaning products has also been associated with higher incidence of asthma, as has birth by Caesarean section rather than vaginal birth.
Happy New Year
Hope the New Year is off to a great start for you all. I hope you had a safe and happy holiday season. May 2009 bring you and your family all the best and I do hope those Allergies have not been a big issue for you all. After finishing my 3rd year of immunotherapy shots, I can truly say that my allergies are improving. I will soon head to another allergenist appointment to see if a 4th year is needed. Perhaps 2009 will be my year! I hope it is yours! Thanks for dropping by!
Happy Holidays
I just want to wish everyone a safe and healthy holiday season. I hope you all have a great Christmas and that the New Year brings much joy into your life and into that of your family. Thank you for stopping by and all the best in this Christmas season!
Merry Christmas everyone