| Farmer's lung | |
|---|---|
 | |
| Hay shed | |
| Specialty | Respirology |
Farmer's lung is a type ofhypersensitivity pneumonitis (also referred to ashypersensitivity alveolitis orextrinsic allergic alveolitis) which is induced by the inhalation of biologic dusts coming fromhay dust ormold spores, or any otheragricultural products.[1] It results in atype III hypersensitivity inflammatory response and can progress to become a chronic condition which is considered potentially dangerous.[2] It is not to be confused withsilo-filler's disease.
These symptoms develop between four and eight hours after exposure to the antigens. In acute attacks, the symptoms mimic pneumonia or flu. In chronic attacks, there is a possibility of the victim going into shock and dying from the attack.[5]
Permanent lung damage can arise due to one's inability to recognize the cause of symptoms.[5] Farmer's lung occurs because repeated exposure toantigens, found in themoldspores of hay, crops, and animal feed, triggers an allergic reaction within the farmer's immune system.[5] The defense mechanisms of the body present as cold and flu-like symptoms that occur in individuals who experience either acute or chronic reactions.[5]
The mold spores are inhaled and provoke the creation ofIgEantibodies that circulate in the bloodstream, these types ofimmune response are most often initiated by exposure tothermophilicactinomycetes (most commonlySaccharopolyspora rectivirgula), which generateIgG-typeantibodies. Following a subsequent exposure,IgG antibodies combined with the inhaledallergen to formimmune complexes in the walls of thealveoli in thelungs.[6] This causes fluid, protein, and cells to accumulate in the alveolar wall which slows blood-gas interchange and compromises the function of the lung. After multiple exposures, it takes less and less of the antigens to set off the reaction in the lung.[7]
Farmer's lung disease (FLD) is permanent and cannot be reversed, therefore in order to prevent the onset of further stages, farmers should inform their doctor of their occupation and if they havemold in their work environment.[3] Prevention of this respiratory illness can be facilitated through theventilation of work areas, drying of materials, and the use of amask when working in confined areas with moldy hay or crops.[5]
[4]Diagnoses of Farmer's lung is difficult due to its similarity tocold andflu-like symptoms.[8] Doctors diagnose patients with Farmer's lung under the following conditions:
Examination procedures may include:
Depending on the severity of the symptoms, FLD can last from one to two weeks, or it can last for the rest of one's life. Acute FLD has the ability to be treated because hypersensitivity to the antigens has not yet developed. The main treatment options are: rest and reducing the exposure to the antigens through masks and increased airflow in confined spaces where the antigens are present.[5] Any exposure to the antigens once hypersensitivity has occurred can set off another chronic reaction.[5] For chronic FLD, there are no true treatments because the patient has developed hypersensitivity meaning that their condition will last the rest of their life.
The growth ofmoldspores occurs when hay is not dried properly.[10] The growth of thesemoldspores accumulates over time and willinfect thehost upon release from the source.[11] When in the air, the farmer may inhale theparticles and induce anallergic reaction.[11] The hay at risk for increased volumes ofspores is found at the bottom of the pile.[11] The incidence of Farmer's Lung Disease peaks during late winter and early spring, and is mostly seen after theharvest season when symptoms have set in.[12] This disease is most prevalent indamp climates.[12]