(ODTS or Grain Fever)

Mary P. Andersen, M.S.
University of Missouri Pulmonary Division

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Organic Dust Toxicity Syndrome (ODTS) is a fairly common illness affecting farmers. ODTS is also called Toxic Organic Dust Syndrome (TODS), grain fever, or pulmonary mycotoxicosis. Its occurrence among farmers is estimated at around 6-8%. However, as many as 30% of swine confinement and grain workers may be affected because of their exposure to high levels of organic dust. ODTS is probably under-reported because symptoms resemble the flu or other mild illnesses. It also has a strong resemblance to an acute episode of the much rarer, but more serious disease known as Farmer's Lung, or hypersensitivity pneumonitis. However, careful medical examination shows these to be very different diseases. ODTS is mild and short-lived, although it may recur. If more than one person is exposed to the same high levels of decayed material, they may suffer ODTS together. Farmer's lung, on the other hand, is an allergic inflammation of the lungs. The rare individual who develops this disease has had prior exposure causing sensitization to mold. This disease may become chronic, disabling and life threatening. Thus, it is important to be able to distinguish these illnesses.

Symptoms of both include cough, fever, chills, fatigue, muscle pain, and loss of appetite 4-8 hours after exposure to spoiled plant materials such as moldy grain, feed, silage or hay. ODTS is also caused by confinement house dust and cotton dust. Farmer's lung, on the other hand, is more broadly known as hypersensitivity pneumonitis. It can affect anyone repeatedly exposed to certain molds, especially thermoactinomycetes or Aspergillus. Mushroom workers and bird breeders are some examples of occupations at risk for hypersensitivity pneumonitis. Air conditioners, humidifiers, and ventilation shafts are examples of places where mold could develop that could affect almost anyone. Floods have also raised concern about mold related illness. The Missouri Department of Health identified 19 cases associated with flooding during 1993 and 1994.

Comparison of ODTS and Farmer's Lung:

                           Farmer's Lung                ODTS
                           -------------                ----
characteristics            allergic                     nonallergic
onset                      4-8 hrs after exposure       4-8 hrs after exposure
resolution                 2-5 days acute phase,        1-10 days, may recur with
                           can become chronic or        repeated exposure but    
                           fatal                        doesn't worsen, never    
exposure to dusts          low to high                  extremely high
chest X-rays               finely nodular densities     usually normal
                           of lower lung fields         
blood gas                  decreased oxygen (pO2)       normal
serum precipitins          positive to thermoac-        usually negative
lung function              mild to severe restric-      usually normal 
lung sounds                crepitations, rales          usually normal
broncho lavage             lymphocytes                  neutrophils
treatment                  corticosteroids, other;      treat symptoms, avoid
                           avoid offending material     offending material

* Caution must be used in interpreting these tests, since many farmers have antibodies to molds implicated in Farmers Lung, even if they do not have the disease.

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