Imminent lung infections capture the world’s attention because of the potential for pandemics. Recent examples include avian influenza and the severe acute respiratory syndrome (SARS). However, even in the absence of new pathogens or pandemics, lung infections have tremendous impact. Lung infections cause more disease than other threats to the public’s health such as cancer, heart attacks, strokes, HIV/AIDS, tuberculosis, or malaria. This persistent and pervasive burden of lung infections receives little attention from the biomedical and public health communities.

Lung infections are especially common and severe among the poor populations.

Some bacteria that cause disease can produce toxic substances that may worsen the disease. Pseudomonas aeruginosa is a bacteria that can produce a variety of toxins and is of special interest for patients with cystic fibrosis and repeated long term lung infections.

Pneumonia is an Infection of the Lung

Pneumonia is an infection in one or both of the lungs. Many small germs, such as bacteria, viruses, and fungi, can cause pneumonia.

The infection causes your lungs’ air sacs, called alveoli to become inflamed. The air sacs may fill up with fluid or pus, causing symptoms such as a cough with phlegm, fever, chills and trouble breathing.

Pneumonia and its symptoms can vary from mild to severe. Many factors affect how serious pneumonia is, such as the type of germ causing the infection and your age and overall health.

Pneumonia tends to be more serious for:

• Infants and young children.
• Older adults . . . people 65 years or older
• People who have other health problems like heart failure, diabetes, or COPD
• People who have weak immune systems as a result of diseases or other factors.

Pneumonia is common in the United States. Treatment for pneumonia depends on its cause, how severe your symptoms are, and your age and overall health. Many people can be treated at home, often with oral antibiotics.

Children usually start to feel better in 1 to 2 days. For adults, it usually takes 2 to 3 days. Anyone whose symptoms get worse should be checked by a doctor.

People who have more severe symptoms or underlying health problems may need treatment in a hospital. It may take 3 weeks or more before they can go back to their normal routines.

Fatigue from pneumonia can last for a month or more.

Bronchiectasis is a Lung Disease that Starts from an Infection in the Lungs

Bronchiectasis is a lung disease that usually results from an infection or other condition that injures the walls of the airways in your lungs. The airways are the tubes that carry air in and out of your lungs.

This injury is the beginning of a cycle in which your airways slowly lose their ability to clear out mucus. The mucus builds up and creates an environment in which bacteria can grow. This leads to repeated serious lung infections. Each infection causes more damage to your airways.

Over time, your airways become stretched out, flabby, and scarred. They can no longer move air in and out.

This can affect how much oxygen reaches your body organs. If your lungs cannot move enough oxygen into your body, bronchiectasis can lead to serious illness, including heart failure.

Bronchiectasis can affect just one section of one of your lungs or many sections of both lungs.

Bronchiectasis usually begins in childhood, but symptoms may not appear until months or even years after you have started having repeated lung infections.

There are two types of bronchiectasis:

1. Congenital bronchiectasis usually affects infants and children. It results from a problem in the development of the lungs in the fetus.
   
   
2. Acquired bronchiectasis occurs in adults and older children. It is more common.
   Bronchiectasis cannot be cured, but with proper care, most people who have it can enjoy a good quality of life.

---

Bronchitis

Bronchitis is a condition in which the bronchial tubes, the tubes that carry air to your lungs, become inflamed.

People who have bronchitis often have a cough that brings up mucus. Mucus is a slimy substance made by the lining of the bronchial tubes. Bronchitis also may cause wheezing (a whistling or squeaky sound when you breathe), chest pain or discomfort, a low fever, and shortness of breath.

There are two main types of bronchitis: acute which is short term and chronic which is ongoing.

Acute Bronchitis

Infections or other factors that irritate the lungs cause acute bronchitis. The same viruses that cause colds and the flu often cause acute bronchitis. These viruses are spread through the air when people cough. They also are spread through physical contact (for example, on hands that have not been washed). Sometimes bacteria cause acute bronchitis.

Acute bronchitis lasts from a few days to 10 days. However, the cough that occurs may last for several weeks after the infection is gone.

Several factors increase the risk for acute bronchitis. Examples include tobacco smoke and also secondhand smoke, air pollution, dust, and fumes. Avoiding these lung irritants as much as possible can help lower your risk for acute bronchitis.

Most cases of acute bronchitis go away within a few days. If you think you have acute bronchitis, see your doctor. He or she will want to rule out other, more serious health conditions that need medical care.

Chronic Bronchitis

Chronic bronchitis is an ongoing, serious condition. It occurs when the lining of the bronchial tubes is constantly irritated and inflamed.

Bronchitis is "chronic" if you have a cough with mucus on most days for at least 3 months a year and 2 years in a row (without another apparent cause). Smoking is the main cause of chronic bronchitis.

Viruses or bacteria can easily infect the irritated bronchial tubes. When this happens, the condition worsens and lasts longer. As a result, people who have chronic bronchitis also have periods when symptoms get much worse than usual.

Chronic bronchitis is a serious, long-term medical condition. Early diagnosis and treatment, combined with quitting cigarette smoking and avoiding secondhand cigarette smoke, can help people live better with this condition. The chance of complete recovery is low for people who have severe chronic bronchitis.

---

Pleurisy and Other Disorders of the Pleura

Pleurisy is inflammation of the pleura. The pleura is a large, thin sheet of tissue that wraps around the outside of your lungs and lines the inside of your chest cavity.

Between the layer of the pleura that wraps around your lungs and the layer that lines your chest cavity is a very thin space. This is called the pleural space. Normally it's filled with a small amount of fluid—about 4 teaspoons full. The fluid helps the two layers of the pleura glide smoothly past each other as your lungs breathe air in and out.

Pleurisy occurs when the two layers of the pleura become red and inflamed. Then they rub against each other every time your lungs expand to breathe in air. This can cause sharp pain with breathing.

Many different conditions can cause pleurisy. Viral infection is the most common cause. Other conditions that can cause pleurisy are:

• Bacterial infections like pneumonia and tuberculosis
• Autoimmune disorders like systemic lupus erythematosus and rheumatoid arthritis
• Lung cancer, including lymphoma
• Other lung diseases like sarcoidosis, asbestosis, lymphangioleiomyomatosis, and mesothelioma
• Pulmonary embolism, a blood clot in the blood vessels that go into the lungs
• Inflammatory bowel disease
• Familial Mediterranean fever, an inherited condition that often causes fever and swelling in the abdomen or lung
• Infection from a fungus or parasite
• Heart surgery, especially coronary artery bypass grafting

Other causes of pleurisy include:

• Chest injuries
• Reactions to certain medicines that can cause a condition similar to systemic lupus erythematosus. These medicines include procainamide, hydralazine, and isoniazid.
• In some cases, doctors can't find the cause of the pleurisy.

Infections like pneumonia are the most common cause of swelling, or inflammation, of the pleura and pleurisy.

Other Disorders of the Pleura:

Pleural Effusion

In some cases of pleurisy, excess fluid builds up in the pleural space. This is called a pleural effusion. The buildup of fluid usually forces the two layers of the pleura apart so they don't rub against each other when you breathe. This can relieve your pain.

However, a large amount of extra fluid can push the pleura against your lung until the lung, or a part of it, collapses. This can make it hard for you to breathe.

In some cases of pleural effusion, the extra fluid gets infected and turns into an abscess. This is called an empyema

You can develop a pleural effusion if you don't have pleurisy. For example, pneumonia, heart failure, cancer, or a pulmonary embolism can lead to a pleural effusion.

Pneumothorax

Air or gas also can build up in the pleural space. This is called a pneumothorax. It can result from acute lung injury or a lung disease like emphysema. Lung procedures, like surgery, drainage of fluid with a needle, examination of the lung from the inside with a light and a camera, or mechanical ventilation, also can cause it.

The most common symptom is sudden pain in one side of the lung and shortness of breath. A pneumothorax also can put pressure on the lung and cause it to collapse.

If the pneumothorax is small, it may go away on its own. If it's large, you may need to have a tube placed through your skin and chest wall into the pleural space to remove the air.

Hemothorax

Blood also can collect in the pleural space. This is called hemothorax. The most common cause of hemothorax is injury to the chest from blunt force or chest or heart surgery. Hemothorax also can occur in people with lung or pleural cancer.

Hemothorax can put pressure on the lung and force it to collapse. It also can cause shock, a state in which not enough blood and oxygen reach important organs in the body.

Outlook for Pleurisy

Pleurisy and other disorders of the pleura can be serious, depending on what caused the inflammation in the pleura.

If the condition that caused the pleurisy or other pleural disorders isn't too serious and is diagnosed and treated early, you usually can expect a full recovery.