Asthma and alveolitis in workers handling cereal seeds

  • Animal breeder
  • Animal foodstuffs industry
  • Baker
  • Combine harvester driver
  • Docker
  • Miller
  • Seed packer
  • Coffee packer

Alternaria, Aspergillus, Cladosporium, Flours, Granarius, Dust mite, Meal, Microbial toxins, Mite, Mycotoxins, Seed debris, Sitophilus granarius, Tenobrio, Ustilago, Weevil, Wheat.

Incidence: Frequent in subjects having a predisposition to bronchial hyperreactivity, atopic subjects and smokers. Several immunological mechanisms can be involved: IgE and precipitins depending on the allergen.

The production of grain dust, drying in a silo, contamination with insects and bacteria are factors which all contribute to the wide aetiology of this disease. Monitoring of respiratory volumes and flow rates over a long time scale is very important. Smoking may be important.

Other than during grain loading/unloading processes using grain blowers (i.e. when much grain dust is produced), it is usually the drying/mixing process inside grain silos that causes the problem. In the case of millers, the exposure to flour is variable depending upon the precise nature of their work. Similarly, the packers who work in grain silos can become sensitized to wheat dust by an IgE-dependant mechanism and by sacks contaminated by different seed debris. In warehouses, a number of other contaminants are also present: rodent urine, cockroaches and bacteria in addition to the usual allergens which include dust mites. Nordic countries and the USA are more affected than Mediterranean countries.
Rhinitis, breathing difficulties, cough, wheezing and sometimes conjunctivitis are the principal symptoms. Equally, pseudo flu like symptoms may be observed. The wide diversity of symptoms is due to the large number of allergens that may be encountered. The increased prevalence of cough and chronic bronchitis over asthma is clear. There are major inflammatory phenomena.
Diagnostic methods
Skin prick tests: (mite and grains), PT and IDR for moulds.
Immunological dosage: RAST/CAP RAST and precipitins.
Monitoring respiratory parameters at home and in the work place.


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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.