Urticaria (itchy rash usually with wheals or welts, often referred to as hives) is common. The lifetime prevalence in the community is 5-20%. Urticaria can be short-lived (less than 6 weeks and called acute urticaria) or persistent (over 6 weeks and called chronic urticaria). The majority of urticaria in the community is not occupational. Urticaria is a sub-type of occupational skin disease and 30% of occupational dermatitis manifests as urticaria.
A large Finnish study found the top occupations with work-related urticaria were bakers, food processors and handlers, dental workers, vet surgeons and assistants, farmers and animal workers, chefs, horticulturalists, lab workers, physicians and nurses, butchers, and hairdressers. These occupations are only the main ones and the list is long and expanding. Many contact triggers, both immune and non-immune, are recorded in the literature.
Occupational urticaria can occur through contact, airborne encounter, physical triggers (e.g. heat, cold, vibration) or as an aggravation of underlying non-occupational chronic urticaria.
The diagnostic work-up involves an imputation of a work-related possibility, attempts to confirm a link, and exclusion of other factors. The temporal relationship between trigger and urticaria is sought, but there is no consensus on the time gap of the purported trigger and symptoms (e.g. one day, one week, one month or even longer).
If a work-related link is considered likely, then the question to decide is causation, aggravation, or both.
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