What are Farmer's Lung and Silo Filler's Disease?

Agriculture is a hugely important part of our society and obviously farming cannot exist without farmers. Unfortunately, some respiratory illnesses are happening more often to those who work in agriculture-related industries than the general population due to increased exposure to agricultural dusts and chemicals. Familiarity with lung diseases like farmer’s lung, silo filler’s disease and organic dust toxicity syndrome, and also about simple methods of prevention, can make farming safer for those in agriculture. 

What's Farmer’s Lung?

This disease is caused by inhalation of dust from moldy hay. It is one of the most common forms of lung diseases and hypersensitivity pneumonitis, it affects up to 7 % of the farming population. The microbial agent responsible for this condition is an organism called thermophilic Actinomycetes which is present in hay. When inhaled, it initiates a defensive reaction in the lungs. It is also found in sugar cane and in mushroom compost. Presentation of the disease may vary but generally three different responses are seen – acute, subacute and chronic.

• Acute - flu-like respiratory illness may develop abruptly along with cough and fever within few hours of intense exposure to moldy crops.
• Subacute - symptoms may include cough, shortness of breath, mild fever and progressive decline in activity tolerance over weeks to months.
• Chronic - develops when disease activity lasts beyond several months. Clinically it may show features of breathlessness with exertion and dry cough. Generally this form of the disease is associated with fibrotic changes in lung.

Information about exposure to certain elements is crucial to diagnosing this condition in addition to blood tests for antibodies, lung function studies and lung imaging studies (CT scan of chest). In some cases, a bronchoscopy is necessary. In difficult cases, a lung biopsy might be needed to examine lung tissue.

For treatment, the most crucial step is to avoid further exposure. During an acute attack, a steroid is often given and gradually tapered off as the patient’s condition improves. If needed, oxygen supplementation is provided along with other supportive measures.

Some other things that can help reduce the chances of developing farmer’s lung include:

• Efficient drying of hay and cereals before storage.
• Use of mechanical feeding systems to reduce the release of airborne mold spores.
• Proper ventilation of farm buildings.

What's Silo Filler’s Disease? 

This preventable disorder is associated with inhalation of nitrogen dioxide produced during the fermentation of silage. Nitrogen dioxide is reddish brown, has a pungent odor and is the main agent causing lung injury. The nitrites combine with organic acids in the silage to form nitrous acid. Within the lungs, nitrogen dioxide reacts with water to form nitric acid.

When inhaled in high concentrations, fluid builds up in the lungs and may develop into a cough, breathing difficulty, or low oxygen saturation. Even a moderate level of exposure can cause a person to experience cough, shortness of breath, chest pain and coughing up of blood.

A few simple measures that may help prevent the development of this condition are:

• Avoid entering a silo for the first 2-3 weeks after filling is complete.
• Use blower fan before entering the silo.
• Use a portable monitor to check oxygen and gas levels in the silo.

What's Organic Dust Toxicity Syndrome?

This is also known as silo unloader’s syndrome or mill fever. This condition is associated with inhalation of material contaminated with certain bacteria and fungal spores including silage, seeds, grains and flour, wood chips, etc. Another source of exposure is use of animal confinement techniques (concentrated animal feeding operations or CAFOs). Clinical illness generally begins within hours of exposure and may include cough, fever and malaise. This is generally self-limited, meaning it resolves without treatment, and most will recover completely.

Contact a CHI Health Lung Center to schedule a lung screening or speak with one of our providers if you think you may have any of these lung diseases.