Sep 5, 2011

Urticaria



Acute urticaria which may last from several hours to several days, often has an allergic nature. In contrast, chronic urticaria, which exists in the weeks and months, very rarely is an allergic reaction. Urticaria often cause food allergens and additives, and drugs (often in the form of pseudoallergy).

Symptoms

Hives can take many forms, but it is always characterized by a rash of blisters, which may merge with each other. The rash can appear on any parts of the body and accompanied by severe itching.

Special forms of urticaria

Angioedema. Process involving a person and is accompanied by swelling of the lips, eyelids ("slit eyes"), mucous membranes and other body parts. Itching is absent, there is a painful burning.

Angioedema is a life-threatening if the process extends to the mucous membranes of the mouth and pharynx. Swollen tongue and back of the throat block the airway and can lead to suffocation.

The causes of urticaria are:

* Food allergens (egg, fish, nuts, fruits);
* Drugs (penicillins, hormonal, sulfonamides);
* Air allergens (pollen, hair, dust);
* Insect bites (bees, wasps);
* Infection (infectious mononucleosis, hepatitis B).

In contrast, allergic urticaria is one that is caused by physical factors: the sun, cold, atmospheric pressure.

Risk of Atopy

Young adults born prematurely with very low birth weight, have almost 60% lower risk of atopy than their peers born at term, in a cord of study conducted in Finland.

"Most studies of long-term consequences of premature birth has negative effects on health" - said Dr. Eero Kajantie (National Institute for Health and Welfare in Helsinki), coauthor of the study.

To study the effect of birthing time on the risk of atopy, the researchers examined 166 adults born before term and weighed 1500 grams or less, and 172 adults born in time from «Helsinki Study of Very Low Birth Weight Adults», ongoing study of preterm birth and adult health.

In the online edition of «Journal of Allergy and Clinical Immunology», the authors identified atopy as a positive reaction to tests for scarification any of six common allergens:
birch, timothy grass, mugwort, cat, dog and dust. Study participants underwent these tests, as well as measuring serum concentrations of IgE, at the age of 18 - 27 years.

The prevalence of atopy was 45.5% in the group of adults with very low weight premature births, compared with 57.9% in the control group. Adjusted odds ratio for atopy to a group of preterm birth was 0.43.

The more premature the birth was, the lower the likelihood of atopy or high levels of specific IgE. Adjusted odds ratio for atopy decreased by 0.82 for each additional week of premature birth.