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 HYPERSENSITIVITY PNEUMONITIS

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HYPERSENSITIVITY PNEUMONITIS

Hypersensitivity pneumonitis is a disease characterized by the inflammation of the alveoli within the lung as a result of an allergic reaction to certain dust particles.

  • Hypersensitivity pneumonitis occurs only in a small number of people after they breathe in certain substances encountered in the environment
  • To develop the condition, repeated and prolonged exposure is necessary (usually over several months to a number of years)
  • If left untreated or not properly controlled, the inflammation can become severe and can cause scarring of the lungs, resulting in severely impaired lung functions
  • Lung scarring is usually non-reversible
  • Detecting the condition in the early stage is very important to prevent permanent lung damage
  • The condition is also referred to as extrinsic allergic alveoli

CAUSES

Hypersensitivity pneumonitis occurs when the immune system reacts strongly to certain inhaled substances. Differences in the immune system may explain why some people react after breathing in certain substances, while others who breathe those same substances do not.

Common environmental sources of particles that cause hypersensitivity pneumonitis include:

  • Animal furs
  • Bird droppings and feathers
  • Contaminated foods such as cheese, barley, sugarcane
  • Contaminated metal working fluid
  • Mold that grows on hay, straw, animal feed, or grain
  • Fungus that grows in air conditioners, humidifiers, and heating systems
  • Bacteria in water vapor from hot tubs

People at an increased risk of developing the condition are:

  • Farmers
  • Vegetable or dairy cattle workers
  • Birds and poultry handlers
  • Grain and flour processing and loaders
  • Veterinary workers and animal handlers
  • Lumber milling, wood stripping, and paper and wallboard manufacturers

Another risk factor is a long exposure to certain chemicals produced in plastic manufacturing, painting, and the electronics industry.

 

SYMPTOMS

Hypersensitivity pneumonitis can show three different types of responses: acute, sub-acute, and chronic response.

An acute attack is brief and severe and begins by heavy exposure to the trigger. Symptoms may develop after 4-6 hours of exposure and may resolve within days upon cessation of exposure to the trigger. Symptoms may include:

  • A dry cough
  • Fever
  • Chills
  • Tiredness
  • Shortness of breath
  • Tightness in the chest
  • Sweating

The sub-acute response occurs in people with low-level exposure to dust over time. Symptoms tend to get worse over time and may include:

  • Cough
  • Chronic bronchitis
  • Shortness of breath
  • Anorexia or weight loss

Chronic response develops after persistent acute attacks and recurrent sub-acute responses. Symptoms may include:

  • Increasing cough
  • Anorexia or weight loss
  • Chronic Bronchitis
  • Shortness of breath
  • Fatigue
  • Lung fibrosis
  • Clubbing of fingers or toes

This type of hypersensitivity can lead to permanent lung scarring

DIAGNOSIS AND TREATMENT

To make a diagnosis, the doctor will review your medical history and see if you have any exposure history to triggers.

Diagnostic tests and procedures may include:

  • Blood tests
  • CT scan
  • Lung biopsies
  • Lung function tests
  • Chest X-rays
  • Bronchoalveolar lavage (BAL)
  • Inhalation challenge test
TREATMENT

The best treatment option is to avoid triggers, as chronic exposure may result in permanent damage. To do this:

  • Remove triggers if possible
  • Replace workplace or other products with alternatives that do not contain triggers
  • Stay away from known source of triggers

 

Corticosteroids or other immunosuppressive medications can also be prescribed to treat the condition

 

Other supportive therapies include:

  • Oxygen therapy
  • Bronchodilators to open the airways
  • Opioids to control shortness of breathe or chronic cough that is resistant to other treatments

In severe cases, lung transplants may be ordered.