Comparative evaluation of Type 1 latex hypersensitivity in patients with chronic urticaria, rubber factory workers and healthy control subjects GAMZE PISKIN 1 ,AYNUR AKYOL 1 ,HATICE UZAR 1 ,NECLA TULEK 2 ,AYSE BOYVAT 1 AND ERBAK GURGEY 1 1 Department of Dermatology, Faculty of Medicine, Ankara University, Ankara, Turkey, 2 Department of Infectious Diseases, Ankara Hospital, Ankara, Turkey Latex hypersensitivity manifests itself most commonly with contact urticaria. In this study, we investigated the frequency of latex hypersensitivity as a possible aetiological factor in patients with chronic urticaria (CU) and compared latex hypersensitivity of CU patients (n ¼ 50) with that of rubber factory workers (n ¼ 50) and healthy controls (n ¼ 50). Prick test with latex and fruit extracts and determination of latex-specific immunoglobulin E (IgE) were performed. As a risk factor, contact dermatitis due to rubber additives was tested by patch test. Latex hypersensitivity was detected in 14% of CU patients, 12% of rubber factory workers and 12% of healthy controls (P > 005). Positive patch test with rubber additives was detected in 6% of CU and 4% of rubber factory workers. 3 of 7 CU patients had sensitivity to fruits in addition to latex hypersensitivity. In 1 patient with CU, the clinical complaints were found to be related to latex hypersensitivity. These findings suggest that the frequency of latex hypersensitivity in CU patients is no higher than that in healthy individuals. However, CU patients should be carefully asked about latex allergy, as we demonstrated that 1 of the CU patients had undiagnosed symptomatic latex allergy. Keywords: chronic urticaria; fruit; natural rubber latex; occupational; rubber manufacture; Type 1 hypersensitivity. # Blackwell Munksgaard, 2003. Accepted for publication 2 May 2003 Chronic urticaria (CU) is a challenge for derma- tologists, as the aetiology remains unknown in 80% of the cases. In various studies, the incidence of determination of an aetiologic factor in patients with CU was found to be between 10% and 80% (1–3). An explanation for this variation could be the differences in patient populations in different studies. However, this variation in the results of different studies might also suggest that, despite intensive clinical and laboratory investigation, the aetiologic factor can easily be overlooked in patients with CU. Type 1 hypersensitivity to natural rubber latex manifests itself mainly by contact urticaria. There are defined risk groups with higher prevalence of hypersensitivity, e.g. health care workers and patients with frequent mucosal latex exposure due to health problems. However, latex exposure is also common in general population because of the use of rubber-containing products, e.g. condoms, gloves and toys (4). Supporting these findings, there is a report of a CU patient who was, later on, found to be indirectly exposed and sensitized to latex (5). In this study, we aimed to investigate the prevalence of latex Type 1 hypersensitivity in CU patients and to compare this prevalence with that in rubber factory workers and healthy controls. In addition, possible cross-reaction of latex allergy with fruit allergies was assessed. Further, co-occurrence of Type 1 latex hypersensitivity with Type 4 hypersensitivity to rubber additives and with atopy was evaluated. Materials and Methods Patients with CU (n ¼ 50), rubber factory workers (n ¼ 50) and healthy controls (n ¼ 50) participated in the study. CU patients were recruited from the outpatient clinic of dermatology. Healthy blood donors were asked to participate in the study to form the control group. Rubber factory workers from the military rubber factory in Ankara were included as the high-risk group for latex allergy. Contact Dermatitis 2003: 48: 266–271 Copyright # Blackwell Munksgaard 2003 Printed in Denmark. All rights reserved CONTACT DERMATITIS ISSN 0105-1873