Farmers Lung 

Farmer Lung

Farmer's lung and thermophilic actinomycetes testing in air samples.

Farmer's lung is a serious respiratory condition and is a type of hypersensitivity pneumonitis. It has also been called air-conditioner lung, humidifier lung, extrinsic allergic alveolitis, mushroom picker's disease, and bird breeder's lung.Farmers are most likely to get it because it's usually caused by breathing in dust from hay, corn, grass for animal feed, grain, tobacco, or some pesticides. This condition was described as early as 1713.   The classic presentation of farmer's lung results from inhalational exposure to thermophilic Actinomyces species and occasionally from exposure to various Aspergillus species.

Thermophilic actinomycetes include a range of bacteria including Saccharopolyspora rectivirgula (formerly Micropolyspora faeni), Thermoactinomyces vulgaris, Thermoactinomyces viridis, and Thermoactinomyces sacchari. These organisms flourish in areas of high humidity and prefer temperatures of 40-60°C. This group of bacteria was originally isolated from decaying compost, hay, and sugar cane. However, more recently, this group of organisms have been found in contaminated ventilation systems.

For people who develop the condition in non-rural areas, it is usually found in home or work place contains high levels of contaminants. Because the particles are so tiny, the normal defenses in your nose and throat miss them, and they go straight to your lungs. Your lungs then try to get rid of the dust, and your symptoms start when your inmune system reacts. Symptoms of acute hypersensitivity pneumonitis may occur 4 - 6 hours after leaving the area. The symptoms of farmer's lung can last from 12 hours to 10 days. Symptoms include: chills, fever, cough, shortness of breath, tight feeling in the chest and tiredness.

For those who are sensitive, repeated exposure to the allergic trigger can lead to more severe symptoms such as chronic cough with phlegm containing pus, shortness of breath, loss of appetite and weight loss. Lung scarring can occur in the later stages of the disease which greatly impacts respiratory health.

The mortality rate from farmer's lung is reportedly 0-20%. Note the following:

Death usually occurs 5 years after diagnosis.

Several factors have been shown to increase mortality rates in farmer's lung, including clinical symptoms occurring more than 1 year before diagnosis, symptomatic recurrence, and pulmonary fibrosis at the time of diagnosis.

Comorbid factors: Although a history of smoking appears to decrease the overall risk for the development of hypersensitivity pneumonitis, a smoking history is the strongest predictor of increased respiratory symptoms once the diagnosis is made. Preexisting bronchial hyper-reactivity with airway obstruction is also a factor.

Biotech Laboratories is NATA accredited to perform the testing of air samples for thermophilic actinomycetes.

References
http://emedicine.medscape.com/article/298811-overview
http://www.medicinenet.com/script/main/art.asp?articlekey=13143