OCCUPATIONAL ASTHMA IN A FARMING ENVIRONM ENT

The prevalence of asthma in a farming environment is significant (from 3-7.7% according to various studies). The clinical picture has not be en specified. The responsible agents are multiple and polysensitisatio n frequent. Numerous substances of vegetable origin may be a cause, po llens, moulds, cereals, oil and protein producing plants, fibrous text iles, diverse plants and wood, etc. Amongst substances of animal origi n the most frequent allergens incriminated are: allergens from mammals (horses, cattle, pigs), allergens from chickens and birds, arthropod allergens, insect allergens. Amongst chemical products those which are at risk to the respiratory system include insecticides, herbicides, f ungicides, antibiotics and antiparasites. The diagnosis of the occupat ional character of asthma is sometimes difficult because of other caus es of lung diseases in farm workers. The aetiological diagnosis is ach ieved by the clinical history, cutaneous tests, a level of specific se rum IgE, and bronchial provocation tests which contrary to asthma in t he industrial environment are not fundamental to the diagnosis except where chemical products are suspected. The mechanisms are sometimes in tricate (IgE dependant mechanisms, non-specific liberation of histamin e, activation of complement, intervention of endotoxins and pharmacolo gical mechanisms...). Prevention may be carried out on behalf of the v ictim (for example wearing filtration masks in dusty work) and also ca rry out various methods to reduce the level of exposure to the allerge n.