Farmer’s lung





Farmer’s lung (FL) is a hypersensitivity pneumonitis induced by the inhalation of biologic dusts coming from hay dust or mold spores or any other agricultural products.



Farmer’s lung occurs because repeated exposure to antigens, found in the mold spores of hay, crops, and animal feed, triggers an allergic reaction in a farmer’s immune system.


It is a type III hypersensitivity inflammatory response and can progress to become a chronic condition which is considered potentially dangerous.


The growth of mold spores occurs when hay is not dried properly.


The mold spores accumulate over time and will infect the host upon release from the source.


When in the air, the farmer may inhale the particles and induce an allergic reaction.


Increased volumes of spores are found at the bottom of the hay pile.


This disease is most prevalent in damp climates.


The defense mechanisms of the body manifest as  cold and flu-like symptoms that occur in those who experience either acute or chronic reactions.


In its acute stage: After four to eight hours symptoms such as headache, irritating cough, and shortness of breath upon physical exertion, appear.


Subacute Stage: Symptoms persist without further exposure, and increase in severity. 


Symptoms of subacute FL include: shortness of breath upon exertion, chronic coughing, physical weakness, occasional fever and sweating, decrease in appetite, aches and pains.


Chronic Stage FL: Debilitating effects are long-term. 


Symptoms include: severe shortness of breath, chronic coughing, physical weakness, occasional fever and sweating at night, decrease in appetite, and general aches and pains.


Acute symptoms develop between four and eight hours after exposure to the antigens, mimicking  pneumonia or flu. 


In chronic attacks, shock and dying from the attack may occur.


Mold spores are inhaled and provoke the creation of IgE antibodies that circulate in the bloodstream.


Similar types of immune response are most often initiated by exposure to thermophilic actinomycetes which generate IgG-type antibodies. 


Following a subsequent exposure, IgG antibodies them combine with the inhaled allergen to form immune complexes in the walls of the alveoli in the lungs.



These immune complexes causes fluid, protein, and cells to accumulate in the alveolar wall which slows blood-gas interchange and compromises the function of the lung. 



With subsequent exposures, it takes less and less of the antigens to set off the reaction in the lung.



It is a permanent an irreversible process.



It is essential to prevent further advancement in the disease stage.



Prevention of this respiratory illness can be facilitated through the ventilation of work areas, drying of materials, and the use of a mask when working in confined areas with moldy hay or crops.



Diagnoses is difficult due to its similarity to cold and flu-like symptoms.



Dagnosis of Farmer’s lung under the following conditions:



A clinical history of symptoms such as cough, fever, and labored breathing when exposed to mold in work environment.



The presence of diffuse lung disease in chronic cases.



Presentation of antibodies when exposed to thermophilic Actinomyces.



The severity of the symptoms can vary from one to two weeks, or they can persist  for life. 



Acute FLD treatment options are: rest and reducing the exposure to the antigens through masks and increased airflow in confined spaces where the antigens are present.



Subsequent exposure to the antigens once hypersensitivity occurs, can set off another chronic reaction.



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.




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