The body's last defense against these tiny invaders is to develop an allergy producing cold or pneumonia-like symptoms. The farmer will develop specific symptoms based upon the intensity of dust and spores to which he has been exposed or the intensity of his body's reaction to the dust and spores. He is also likely to develop an increased sensitivity to mold exposure, having more severe reactions with fewer exposures. In all cases, each exposure aggravates the problem. This is the most noticeable condition which typically begins 4 - 8 hours after exposure.
Most farmers ignore the symptoms because they are so similar to a common summer cold.
These symptoms may be most severe for a 12 to 48 hour period and then remain for as long as two weeks. Acute Farmer's Lung is a short term disease, but the symptoms will recur with each exposure. This is a more serious condition because symptoms will be stronger and remain longer even with no further exposure to moldy dust particles. This is the most serious condition because of its gradual onset and its long-lasting debilitation. At the chronic state, the disease becomes irreversible.