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Summary Article: Respiratory Diseases from Encyclopedia of Global Health

Respiratory illnesses are common clinical manifestations encompassing numerous conditions ranging from the benign common cold to chronically debilitating conditions inclusive of lung cancers and Chronic Obstructive Pulmonary Disease (COPD). With a prevalence rate affecting over 78 percent of the U.S. population, respiratory conditions warrant significant attention in today’s health care system. The World Health Organization attributed over 226,000 deaths in the Americas and almost 4 million deaths worldwide to respiratory conditions. The high prevalence rate not only implicates a potential for an economic burden due to a decrease in a labor work force but also drives up health care costs for admissions as a result of such conditions.

Although many respiratory diseases may entail predisposing factors inclusive of age, genetics, locations, and behavior patterns, certain pulmonary conditions have the potential to inflict disease in virtually any age group. Of the numerous respiratory conditions that exist, the most commonly occurring conditions include: Common Cold, Influenza, Pneumonia, Chronic Obstructive Pulmonary Disease (COPD), Cystic Fibrosis, Tuberculosis and Lung Cancer.

COMMON COLD

Of all respiratory conditions, the most common includes the common cold with an incidence rate of 22 percent percent in the United States. It is often more prevalent in the winter months however, may present at any time of the year. In most cases, the most common causative agent is a rhinovirus although other etiological agents include: coronavirus, echovirus, paramyxovirus and coxsackievirus. Symptoms entail cough, nasal congestion, headache, fatigue, and generalized malaise.

The condition is self-limiting and as a result, treatment is often supportive. Symptoms routinely resolve within 3 to 5 days with the exception of patients with compromised immunity, which may develop into more serious and progressive illnesses such as pneumonia. Usually this progression occurs as a result of bacterial co infection either from within the body or from an external source. As the mode of transmission is highly facilitated through respiratory droplets, preventative measures should include frequent hand washing and avoiding affected disease carriers.

INFLUENZA

Another common illness in the winter months includes influenza, also known as the flu.

In year 2000, the incidence of the flu was approximately one in three people and affecting 97.9 million individuals in the United States. The most common causes of influenza are influenza A and influenza B. Symptoms of the infection are somewhat more severe than those for the common cold. Flu-like symptoms include cough, runny nose, fevers, chills, headaches, muscle weakness and the general feeling of being drained of energy. The infectious agent mainly attacks the upper respiratory tract. In neonates, the elderly, and immunocompromised patients, the agent may also cause pneumonia and even death. However, a full recovery is almost always expected among infected healthy individuals. Treatments for the flu many consist of fluid replacement and rest. However, in extreme cases, anti-viral medications such as amantadine may be indicated.

Respiratory illnesses range from the common cold to lung cancer to Chronic Obstructive Pulmonary Disease (COPD).

With the increased availability of the influenza vaccine, the incidence of cases is decreasing. Among the elderly, vaccination is thought to reduce influenza-related morbidity by 60 percent and influenza-related mortality by 70 to 80 percent. Among healthy adults the vaccine is very effective in terms of reducing influenza morbidity, and vaccination has been shown to have substantial health-related and economic benefits in this age group.

Recently, a new strain of the Influenza A, or avian flu virus, present in birds has become a public concern. Due to its high infectivity and the increased amounts of birds infected, many precautions are being taken to prevent a full-blown outbreak of the illness. Its transmission pattern is facilitated through the secretion of infected organisms and further perpetuated through respiratory droplets from human to human contact.

The symptoms of avian influenza vary greatly. They can be as mild as a sore throat, to normal flu-like symptoms, to severe conditions such as pneumonia, and other severe and life-threatening complications. The symptoms of avian influenza may depend on which virus caused the infection. There is currently no treatment available, but research has been ongoing in hopes of developing possible vaccines since 2005.

PNEUMONIA

Pneumonia is a leading cause of death in the elderly and immunocompromised individuals. Pneumonia is an infection of the lungs that can be due to bacterial or viral organisms, foreign bodies or even chemicals. The manifestation of such an infection is fluid build up in the alveoli, the small air sacs of the lungs, and causing symptoms. Typically, patients present with cough, chest congestion, fever, chills, chest pain and difficulty breathing. However, some patients may have atypical pneumonia or walking pneumonia, that is patients don’t usually have any symptoms and the pneumonia is often an incidental finding. A vaccine is available which is usually taken every five years and is composed of 23 strains of the common pneumonia organisms.

Diagnosis is often made based on clinical signs and symptoms however, sputum culture and chest radiographs are routinely ordered to confirm a diagnosis of pneumonia. Depending on the cause of the pneumonia, the sputum may be different colors. Often times yellowish/brown sputum indicated bacterial infection usually by Streptococcus pneumoniae, a greenish sputum denotes a pseudomonal infection and a whitish/clear could be present in viral illness. On X-ray, the pneumonia gives a “washed-out” appearance in one area of the lung and obliterates the diaphragmatic angles due to fluid buildup.

Treatment of pneumonia is specific to the etiological agent responsible for the infection and often includes antibiotics, symptom management, and prevention of future complications.

CHRONIC OBSTRUCTIVE PULMONARY DISORDER

Chronic Obstructive Pulmonary Disease (COPD) is a generalized term that covers many different obstructive pulmonary conditions and affects over 13.5 million Americans. These include chronic bronchitis, asthma, emphysema, and bronchiectasis. They all, however, work through an obstructive process by restricting expelled airflow out of the lungs, resulting in excessive trapped air within the lungs. Typically COPD patients clinically present with respiratory difficulty, expiratory wheezing, abnormal pulmonary function studies resulting in an increased FEV1/FVC and high residual lung volumes, and a flattened diaphragmatic affect on chest radiography.

Chronic bronchitis is a form of COPD affecting over 12 million Americans. The condition is clinically characterized by productive cough for more than three consecutive months for at least two years. It is most often seen in smokers, but may also be a result of exposure to various environmental toxins such as solvents or coal dusts.

The pathophysiology is most adequately demonstrated by a hypertrophy, or increased size, of the mucus-secreting goblet cells in the bronchioles. Usually patients present with a productive morning cough and experience remarkable respiratory distress. Patients who are smokers are encouraged to quit smoking and mucolytic agents may be prescribed to dissolve excess mucous.

Asthma is another form of COPD and is characterized as bronchial hyper reactivity to certain allergens or triggers that is reversible. It is characterized by bronchoconstriction and wheezing that is often audible. It is one of the most common childhood diseases, however, many times it resolves by adulthood. Approximately 6.4 percent of the people in USA have asthma. Treatment is symptom-based and for patients with a mild form of the disease, a bronchodilator such as albuterol is often prescribed. However, in patients with more persistent symptoms, daily treatment with various medications is tried. These include beta 2 agonists such as salmeterol, mast cell (inflammatory cells responsible for the release of histamine) desensitizing agents such cromolyn sodium, anti-inflammatory agents such as corticosteroids, or antileukotirenes such as zileuton and zafirlukast. These drugs are used to dilate the airways, prevent bronchospasm and decrease the inflammatory response of the body. In patients refractory to those treatments, hospital management with IV steroids, ipratropium and nebulizaer treatments may be indicated.

Emphysema is a COPD condition that is defined by the loss of lung elasticity as a result of the destruction of the alveolar walls. It results in enlargement of the air spaces and collapse of the small airways resulting in the entrapment of air. There are four main types of emphysema. Only the panacinar type is of restrictive pattern, the rest maintain an obstructive patterns. Panacinar emphysemia is a genetic disorder resulting in a deficiency of alpha-1-antitrypsin. Alpha-1-antitypsin is used to produce a molecule known as surfactant, which lines the alveoli and allows the recoil function of the lungs. The other types of emphysema are distal acinar, which is a result of aging; centoacinar, a result of smoking; and bullous, which is due to infection by Staphylococcus aureus or Pseudomonas aerginosa.

The prevalence of emphysema is approximately 2 million Americans. Emphysema is an irreversible degenerative process for which no treatment is currently available. However, patients are encouraged to stop smoking and given symptomatic treatment based on acute exacerbations, similar to the treatments for the other COPD conditions.

Bronchiectasis is a chronic infection of the bronchi, which is most often seen in patients with cystic fibrosis. It is also seen in patients with bronchial obstruction, such as aspiration patients, immunodeficient patients, and patients with poor ciliary motility. Diagnosis may be made on clinical presentation, patient history, and laboratory studies inclusive of white blood cell count and chest radiography.

CYSTIC FIBROSIS

Cystic fibrosis is a systemic manifesting genetic illness affecting virtually every organ. Patients with the disease produce very thick mucous secretions that block the airways resulting in infections and difficulty breathing. Patients generally have a poor prognosis with an average life expectancy of 20 to 30 years. Currently there is no curative treatment available for the disease. However, various daily percussion techniques are used to help clear the secretions from the lungs. Humidifiers and bronchodilators are used to improve airflow and often times prophylactic antibiotics are used to prevent infections. The most common infections seen in these patients are due to Pseudomonas aergenosa. Cystic fibrosis is most common in people of European descent, with a special predisposition to the Ashkenazi Jew population. Approximately 2,500 children are born every year with the disease, with 1 in every 3,300 Caucasian children having the disease.

TUBERCULOSIS

Tuberculosis (TB) is a chronic infection caused by the bacteria Mycobacterium tuberculosis and has been noted to cause more deaths than any other infectious disease in the world. Although, the disease is much more common and deadly in developing countries when compared to cases in the developed world. Approximately one-third of the world’s population is infected with the bacteria. However, it affects less than 200,000 Americans. In 2004, the prevalance of active TB disease was 14.6 million people with an incidence of 8.9 million people and mortality of 1.7 million people, mostly in developing countries.

The bacteria invades the hilar nodes of the lungs and also forms a Ghon focus, which is usually located in the lower lobes. The combination of the two is called the ghon complex. The body heals and develops immunity and hypersensitivity, which then results in a positive TB test, a commonly used diagnostic criteria for TB. The tuberculin test, also known as the Mantoux test, is performed by injecting PPD tuberculin on the forearm directly under the skin. The result is read 48 hours later by measuring the amount of induration present. If it is a healthy patient with no known risk factors, the test is considered positive if it measure >15mm across. In patients who are recent arrivals from countries where TB is prevalent, IV drug users, children <4 years old, residents and employees of health care facilities and lab personnel, and people with chronic medical condition, a flare of 10 mm or more is positive. Finally, if it is a patient who is immunocomprosmised, has a previous history of TB exposure, or with a positive chest x-ray consistent with previous TB, an induration of 5 mm or more is positive.

Secondary TB is seen in partially hypersensitized hosts. On chest x-ray, a fibrocaseous cavitary lesion is noted at the apices of the lungs. It may be due to reactivation of previously infected hosts, in which case the previous ghon complex may be seen on x-ray as well. TB may also spread from the lungs and manifest itself extrapulmonarily in the spine, brain and spinal cord, renal or gastrointestinal systems.

All TB patents must go on medical treatment with multi-drug therapy due to increased cases of antibiotic resistance. Such treatment includes combination therapy of Rifampin, Isoniazid, Pyrazinamide, Ethambutol, and Streptomycin. Furthermore, due to TB’s extremely infective transmission pattern, all close contacts must be treated prophylactically. Treatment guidelines for exposed patients include 6 months of isoniazid and vitamin B6 therapy for effective prophylaxis.

LUNG CANCER

Lung cancer is one of the leading causes of death worldwide, accounting for up to 3 million deaths annually. The affliction has a poor prognosis with less than five year life expectency subsequent to a new diagnosis. Although mostly affecting both genders equally, more women die of lung cancer than any other cancer including breast, ovarian, and uterine cancers combined.

Risk factors with the greatest accountability leading to lung cancer include long term exposure to inhaled carcinogens such as tobacco smoke, radon gas, and asbestos. Genetic predisposition, viral agents, and the presence of primary tumor elsewhere in the body are also other commonly known risk factors.

Symptomatic findings leading to a diagnosis of lung cancer may include respiratory distress, coughing up blood, chest pain, abnormal weight loss, fatigue, loss of appetite, difficulty swallowing, fevers, and hoarse voice. Clinical diagnosis of lung cancer is routinely made subsequent to a thorough medical history with particular focus to social habits, family history of cancers, and a past medical history. Patients are routinelly chest radiographed and a lung biopsy is taken to ensure a malignant pathology before treatment options are evaluted. Patients may also undergo pulmonary function studies to evalute respiratory status to ensure that they are eligible for elective surgery.

With the several types of lung cancer that exist, treatment for the condition depends on the specific cell type, extent of spread, and the patient’s health status. Typical treatment options for the condition include chemotherapy, radiation therapy, and surgery. Although, they have been known to be used in combination, treatment options are always customized for individual cases.

    SEE ALSO:
  • Asthma; Bronchitis; Chronic Obstructive Pulmonary Diseases; Emphysema; Pulmonary Fibrosis.

BIBLIOGRAPHY
  • A J Alberg; J M Samet, “Epidemiology of lung cancer,” Chest (January 2003).
  • CDC, “Key Facts About Avian Influenza and Avian Influenza Virus,” www.cdc.gov/flu/avian/gen-info/facts.htm (cited June 2007).
  • NA Hanania, et al., “Treatments for COPD,” Respiratory Medicine (v. 99 Suppl B, 2005).
  • WHO, “Influenza,” www.who.int/mediacentre/factsheets/fs211/en/ (cited June 2007).
  • Wikepedia, “Lung Cancer,” www.wikepedia.com (cited June 2007).
  • Wikepedia, “Pneumonia,” http://en.wikipedia.org/wiki/Pneumonia (cited June 2007).
  • Utkarsh Acharya, BS
    Ohio University College of Osteopathic Medicine
    Amee Mehta, MD
    Independent Scholar
    Copyright © 2008 by SAGE Publications, Inc.

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