Byssinosis

Etiology

Classically, exposure to cotton dust during the spinning and manufacturing process causes byssinosis. However, exposure to jute, flax, and hemp fibers have been implicated in its development. Recent studies identified that endotoxin released from the cell wall of bacteria within textile fibers contributes to byssinosis symptoms. 

People who smoke are at a high risk for acquiring the disorder.[4],[5]

Epidemiology

Data published by the Center for Disease Control (CDC) confirms a significant decline in the number of reported deaths from byssinosis between 1979 to 2010; however, comprehensive epidemiological data are lacking. Based on some older data, the quoted prevalence of byssinosis in the United Kingdom about 4%.

Outside of North America, byssinosis is not rare at all. In countries where cotton industries flourish, such as India, Pakistan, Nepal, Sri Lanka, and Bangladesh, byssinosis is common. In addition to the cotton industry, exposure to jute, hemp, and flex also cause byssinosis. The general population in these countries also smokes heavily which tends to exacerbate the symptoms. Despite modernization and introducing better working environments, byssinosis still is common in many parts of Pakistan, India, Indonesia, Ethiopia, Turkey, and Sudan.[6],[7]

Pathophysiology

Not only is cotton dust implicated in the pathogenesis but also the endotoxin level in the work environment. This endotoxin is a lipopolysaccharide found in the outer membrane of gram-negative bacteria which reside within the cotton dust. Exposure has been implicated as the key mediator of respiratory disease among these workers with studies showing a decline in FEV1 with endotoxin exposure. However, this is not uniform, and there seems to be a variable response - with an even greater decline in FEV1 in those with polymorphisms in the tumor necrosis factor (TNF) gene.[8],[9],[10]

History and Physical

The beginning steps in yarn preparation produce the most dust. Therefore, the closer to the beginning of the process the person is, the higher the level of dust exposure and the greater risk of experiencing a pulmonary reaction or response.

In the initial stages, symptoms manifest as frequent coughing, chest tightness, dyspnea, and at times, wheezing, particularly within a few hours of exposure (or reexposure) to the workplace. Hence, patients usually report symptoms towards the beginning of their work week and thus the term Monday fever. This is in contrast to patients with occupational asthma who experience symptoms towards the end of their work week. Once exposure and lung irritation becomes persistent, patients will no longer have cyclical symptoms and progress to the chronic byssinosis state.

In conjunction with the above symptoms, cough with sputum production may also manifest, which can lead to a misdiagnosis of chronic obstructive pulmonary disease (COPD) or bronchitis.

Evaluation

There are no known diagnostic tests for byssinosis. However, acute exposure to cotton dust can result in a serological increase in leukocyte count. The diagnosis is often difficult because the condition can mimic asthma and many other pneumoconioses. Besides the physical exam, which is nonspecific, a chest x-ray is required to rule out other pathologies. The biggest clue to the disease is that the patient will usually complain that the symptoms get worse when he or she comes to work on Monday (hence the name Monday disease) and gets better when off work.

In a small proportion of the patients, physical examination was notable for the presence of fine basilar rales.[11] X-ray examination demonstrated the presence of hyperlucency, diaphragm flattening, and emphysema.[6] Diffuse, ill-defined haziness, mainly in the lower lung fields was also seen. A chest CT scan is usually done when the diagnosis is uncertain or when one wants to rule out other disorders. The available literature on radiological findings is limited, however, ground-glass opacities distributed largely in a basal fashion with centrilobular nodules, on HRCT, have been reported.[12]

Pulmonary function testing (PFT) can support suspected byssinosis by revealing a decline in forced expiratory volume over 1 second (FEV1) below 80% of their predicted values or a greater than 5% decline in their intrashift FEV1. The normal, physiologic 20 mL to 30mL annual decline in FEV1 seems to be accelerated to a value closer to 50 mL/year in cotton workers.

Treatment / Management

Removing themselves from the work environment seems to be a beneficial approach for these patients. However, the available data on an annual FEV1 decline is conflicting.

After that symptomatic management with short- and long-acting, inhaled beta-agonists and perhaps corticosteroid inhalers may be necessary. Bronchodilators may be required for many months to improve symptoms. A short course of steroids does help those with severe symptoms.

It is vital that the patient stop smoking.[13],[14](B3)

Differential Diagnosis

• Asthma
• Pneumoconiosis
• Asbestosis
• Farmer's lung
• Interstitial lung fibrosis
• Hypersensitivity pneumonitis
• Sarcoidosis
• Silicosis

Prognosis

The majority of people recover uneventfully with treatment, but at the same time, one needs to avoid exposure to cotton. For those individuals who are misdiagnosed or untreated, the chronic exposure to cotton can lead to lung fibrosis and impaired lung function. Most of these individuals will require oxygen and have impaired exercise function. Deaths from chronic exposure are not uncommon in Pakistan and India where textile industries still flourish, without preventive measures for workers.

Complications

• Lung fibrosis
• Oxygen dependency
• Disability
• Reduced exercise tolerance
• Premature death