Chronic urticaria in latex allergic patients: two case reports

Food allergy: from diagnosis to treatment

Adverse food reactions, an adverse health effect arising from an immune or nonimmune response that occurs reproducibly on the exposure to a given food, can be divided into toxic and hypersensitivity reactions. When an immunologic mechanism has been shown, hypersensitivity food reactions should be referred to as food allergy that may be IgE- or non-IgE-mediated. Food allergy diagnosis is mainly guided by a correct and accurate history and physical examination, thus leading to prick test and elimination diets. The treatment gold standard is still represented by an elimination diet together with antihistamines and corticosteroid usage in order to reduce the gastrointestinal and potentially life-threatening systemic symptoms. Other treatments are currently under investigation with promising results.

Food allergy and food intolerance: diagnosis and treatment

Food allergy is a matter of concern because it affects about 0.5-3.8% of the paediatric population and 0.1-1% of adults, and as well may cause life-threatening reactions. Skin prick testing with food extracts and with fresh foods, the measurement of food-specific IgE, elimination diets and a double-blind, placebo-controlled food challenge are the main diagnostic procedures; many non-validated procedures are available, creating confusion among patients and physicians. The treatment of food allergy is still a matter of debate. Antihistamines, corticosteroids and, if necessary (in case of anaphylaxis), epinephrine, are the drugs of choice for the treatment of symptoms of food allergy. Sodium cromolyn may be used prophylactically even though there are no controlled studies certifying its efficacy. The only etiologic treatment of food allergy is specific desensitization. Sublingual-oral-specific desensitization has been used by our group for the treatment of food-allergic patients with a high percentage of success.

Anaphylactic reactions during cesarean section

Sensitization to latex seems to occur more frequently in women than in men. Obstetric and gynecological surgical procedures have recently been shown to be a common setting for latex anaphylaxis. We analyzed all the cases of anaphylactic reactions during 1240 cesarean sections in 2004; the patients were questioned for risk factors and underwent allergy testing for drugs and latex. Four patients had anaphylaxis under spinal anesthesia and in all cases it was due to latex allergy. Reported symptoms included facial edema, profuse sweating, itching, generalized erythematous rash and hypotension. Only one patient manifested a severe reaction which included bronchospasm, dyspnea, tachypnea and anaphylactic shock, requiring orotracheal intubation and epinephrine. Our data showed a high incidence (1:310) of intraoperative latex anaphylactic reactions in the one-year study period. This may be related to the very specific population (all women) in a very specific setting (obstetrics). To prevent anaphylactic reactions during obstetric surgery it is important to identify potential risk factors to include, for example atopy, adverse reactions to foods and latex items. If latex allergy is confirmed or strongly suspected, patients should be managed in a latex-safe environment. Premedication with antihistamines and steroids might be useful to further reduce the risk. After the delivery, specific desensitization may represent a good therapeutic option.

Latex allergy and skin

PURPOSE OF REVIEW

In this review we address the prevalence and outcome of latex allergy in health care workers (HCWs). Recent findings in natural rubber latex (NRL) allergens and trials of specific immunotherapy (SIT) are also of interest.

RECENT FINDINGS

A study involving skin prick test (SPT) screening in HCWs in Russia and adjacent countries found a prevalence of latex allergy of 1.9%. Questionnaire studies performed in Wales and in the USA identified prevalence rates of about 0.6%. An intervention undertaken at the Mayo Clinic, in which only gloves with low or undetectable allergen levels were allowed, reduced markedly the incidence of NRL allergy. Two studies, one from Finland and another from Ohio, showed that outcomes in latex-allergic HCWs are generally good. A study involving SPT screening showed that 6% of construction workers had latex allergy. A questionnaire study among allergists practicing in the USA showed that 62% performed latex SPT and 6% reported anaphylaxis, which mostly occurred while using a homemade SPT solution. Hev b 2, Hev b 5, Hev b 6.01 and Hev b 13 produced positive SPT reactions in over 60% of latex-allergic individuals. Topical application of NRL in a murine model of protein contact dermatitis caused a striking increase in prohevein-specific (Hev b 6.01) immunoglobulin E levels, together with a T-helper-2 type dermatitis. A placebo-controlled SIT trial with NRL extract alleviated cutaneous symptoms but caused some systemic reactions in latex-allergic patients.

SUMMARY

Low prevalence rates suggest that the peak of the latex allergy epidemic has already passed in HCWs. Hospital-wide interventions requiring use of low-allergen gloves reduce sensitization and changing gloves to nonlatex ones, or even using low-allergen latex gloves, in the affected individuals appears to confer adequate secondary prevention. In the USA there is an urgent need for standardized latex SPT reagent. Hev b 5 and Hev b 6.01 are major in vivo NRL allergens. Findings in mice suggest that NRL proteins eluting from latex gloves may also cause hand eczema in humans. SIT with NRL extract must still be considered an experimental treatment.