Environmental determinants of work-related asthma symptoms on table grape farms: indoor domestic mites or outdoor spider mites?

It is well recognised that domestic mites are an important cause of allergy and asthma worldwide. Among the domestic mites, both house-dust mites and storage mites have been implicated in causing allergic symptoms among both farming and non-farming populations, despite farmers showing relatively lower prevalences of sensitisation to most common inhalants. In the occupational context, house-dust mites have been implicated in causing allergic symptoms and asthma among woodworkers, avian mites among poultry workers and storage mites among bakery and grain mill workers. More recently, outdoor mites such as spider mites have emerged as an impor- tant allergen, causing allergic diseases, including asthma, among farming as well as non-farming populations. The farming population is unique in that domestic and outdoor mites may both be important sources of allergens as most workers work and live on the farm, thereby blurring the distinction between occupational and non-occupational factors that contribute towards allergic symptoms and asthma