The flu is a viral infection caused by influenza virus. Besides seasonal flu, there is also the "swine" flu which cause caused worldwide outbreak in 2009-10 (Pandemic). Bird flu ("avian flu") is a severe form of the flu that is caused by a type of flu virus that first infected birds.
Most important strain for humans is H1N1 and H3N2
Pleural effusion is accumulation of fluid around (not inside) the lungs. Most common causes include infections like tuberculosis, pneumonia; heart failure, kidney disease, cancer etc
Treatment depends on your symptoms and the cause. If effusion is small, it may be taken out with needle for tests.
A pneumothorax occurs when air leaks out of the lung and accumulates in pleural space between lung and chest wall. This is one of the causes of collapsed lung. Its severity varies from mild to severe based on amount of air collected. Severe pneumothorax can be life threatening and needs immediate treatment.
Interstitial lung disease a group of lung disorders which causes inflammation and sometimes scarring in the lungs. This leads to difficulty inn oxygenation of blood. Treatment depends on what is the cause and how severe is the disease. If its because of infection, you will be prescribed medicine.
Pulmonary embolism (or "PE") is a blockage the blood vessels that supply blood from hearth to the lungs for oxygenation. Usually it is caused by blood clots in leg veins. Sometimes it can also be caused by air bubble, fat globules or tumour pieces.
Bronchitis is infection and inflammation of bronchi- tubes that carry oxygen in the lungs. Usually bronchitis occurs after a person gets cold or flu and is usually viral infection initially. Antibiotics may not act during this phase. If it gets secondarily infected with bacteria, antibiotics would be required. We will discuss regarding acute bronchitis here. Chronic bronchitis is something that smoker may get.