[Diagnosis and therapy of urticaria]

Urticaria and infections

Urticaria is a group of diseases that share a distinct skin reaction pattern. Triggering of urticaria by infections has been discussed for many years but the exact role and pathogenesis of mast cell activation by infectious processes is unclear. In spontaneous acute urticaria there is no doubt for a causal relationship to infections and all chronic urticaria must have started as acute. Whereas in physical or distinct urticaria subtypes the evidence for infections is sparse, remission of annoying spontaneous chronic urticaria has been reported after successful treatment of persistent infections. Current summarizing available studies that evaluated the course of the chronic urticaria after proven Helicobacter eradication demonstrate a statistically significant benefit compared to untreated patients or Helicobacter-negative controls without urticaria (p < 0.001). Since infections can be easily treated some diagnostic procedures should be included in the routine work-up, especially the search for Helicobacter pylori. This review will update the reader regarding the role of infections in different urticaria subtypes.

Urticaria: its history-based diagnosis and etiologically oriented treatment

INTRODUCTION

The term "urticaria" refers to any of a group of distinct skin conditions that are characterized by itchy, wheal-and-flare skin reactions (hives). In spontaneous urticaria, the most common type, the hives seem to arise without provocation.

METHODS

Selective review of the literature, including current guidelines.

RESULTS

Spontaneous urticaria is divided into acute (lasting less than six weeks) and chronic types. The pathognomonic itching, hives, and angioedema arise by the same mechanism--cutaneous mast cell activation and release of histamine and other mediators of inflammation--in both acute and chronic urticaria, but these two disorders have different etiological profiles. The underlying cause of acute urticaria cannot be identified in about half of all cases. Chronic urticaria, which is much rarer, is usually caused by autoreactivity, chronic infection, or intolerance to food additives. If the condition persists after the underlying cause has been treated or eliminated, non-sedating antihistamines are the agents of first choice for symptomatic treatment.

DISCUSSION

Unlike acute urticaria, which is self-limited and should be treated symptomatically, chronic urticaria should be treated by the identification and elimination of underlying causes, which is usually curative.

Giardia lamblia — Ursache von Urtikaria und Pruritus oder zufällige Assoziation?

Three patients with chronic urticaria or pruritus were found to suffer from an asymptomatic intestinal infection caused by the protozoan Giardia lamblia. Treatment with metronidazole per os or tinidazole per os was successful; the pruritic symptoms in one patient improved markedly.Giardia lamblia (Giardia intestinalis) are enteroparasites and produce gastrointestinal symptoms such as acute and chronic diarrhea. Cutaneous manifestations associated with giardiasis occur extremely rarely. Urticaria and itching may be explained as an infection-associated allergy. Hitherto, the following cutaneous signs have been described: urticaria, angioedema, mouth ulcers, pruritus, atopic dermatitis, and anal eczema.We considered that the cutaneous manifestations described here, i. e., urticaria and itching, were secondary to the associated gastrointestinal infection due to Giardia lamblia cysts and trophozoite forms, as they disappeared under specific treatment with metronidazole or tinidazole.

Aktuelle Positionsbestimmung zur Bedeutung von Nahrungsmittelallergien und -unverträglichkeiten bei der Urtikaria

Foods are usually the first suspect as the cause of urticaria. However, a causal relationship is found only in special subtypes of urticaria. IgE-mediated food allergy should be clearly separated from non-allergic hypersensitivity (pseudoallergic reactions). The former may play a role in acute urticaria, particularly in patients with atopic dermatitis. The responsible food proteins vary with age. IgE-mediated sensitization can apply to food-dependent exercise-induced urticaria/anaphylaxis but more often the combination of food intake (irrespective of which type) plus exercise results in symptoms. In chronic urticaria, IgE-mediated sensitization to food is normally irrelevant while pseudoallergic reactions to food additives and perhaps also to biogenic amines may be involved. Another urticaria subtype that may be caused by food is contact urticaria which is mostly found in the context of occupational food handling. Very rarely anisakiasis and nickel may cause food-induced urticaria. Aspirin is able not only to exacerbate and aggravate urticaria but can also enhance food-dependent urticaria.

[Emergencies in allergology]

The clinical presentation of allergological emergencies is heterogeneous. The most important conditions are anaphylaxis (which is frequent) and Stevens-Johnson syndrome or toxic epidermal necrolysis (which are rare). In the acute phase it is most important to recognize the exogenous elicitation of the condition as soon as possible, otherwise severe sequelae, even death of the patient, may occur. Management is based on immediate elimination of possible causative agents and symptomatic therapeutic measures. Furthermore, allergological diagnostics are necessary without delay to identify what has elicited the reaction. This information makes possible long-term treatment in order to avoid further hypersensitivity reactions.

[Urticaria. Classification and diagnosis]

Urticaria belongs to the most frequent dermatologic diseases. Although the pathogenesis of urticaria is not fully understood, systematic studies in recent years have identified the most important triggering factors of the different forms of urticaria. Based on these results, it is recommended to restrict diagnostic procedures in acute urticaria to history and physical examination, while in chronic urticaria, one should exclude drugs, infections, pseudoallergic reactions, and autoimmune processes as causes. For the diagnosis of physical urticaria, standardized provocation test are recommended.