What Is Pneumonia? 

Pneumonia is an inflammation of the lungs caused either by a viral or a bacterial infection. Symptoms can include:

• Alterations in the normal body temperature: Fevers. Older people may exhibit a subnormal temperature
• Severe cough, accompanied by chest pain that fluctuates with breathing (pleurisy) and purulent yellow-green discharge
• Shortness of breath
• Sweating and chills
• Headache
• Muscle ache
• Fatigue
It’s particularly important to seek medical attention if you exhibit these symptoms and are over 60 years of age, smoke, drink excessive amounts of alcohol, are undergoing chemotherapy or taking an immunosuppressant medication such as prednisone.

Pneumonia Complications

Occasionally, pneumonia can develop into a more serious disease. If the microorganism causing bacterial pneumonia invades the blood stream, you can develop bacteremia. Even if you’re diagnosed with viral pneumonia, you can develop an abscess in your lung that fills with bacteria and pus, requiring antibiotics and, in some cases, manual drainage. Fluid may build up between the lungs and the membranes called pleura that surround the lungs: This condition is called pleural effusion.

Causes of Pneumonia

Bacterial infection is the most common cause of pneumonia. When the body is weakened by a cold or the flu, bacteria have an easier time penetrating the body’s normal defense mechanism. In the U.S the microorganism most often implicated is Streptococcus pneumoniae. Bacterial pneumonias can be treated with antibiotics.

Up to one-third of pneumonia infections in the U.S however, are caused by viruses such as the flu virus, syncytial virus, rhinovirus, herpes simplex virus and severe acute respiratory syndrome (SARS). In fact, viral pneumonia is the most common type of pneumonia in children under five years of age. While most cases of viral pneumonia in adults are mild, in children they can be quite severe. Viral pneumonias cannot be treated with antibiotics.

Fungal infections have also been implicated in pneumonia. The Coccidioidomycosis virus found throughout the Southwest causes a type of pneumonia called Valley Fever. Individuals with suppressed immune systems are also at risk for pneumonia secondary to Histoplasmosis, Cryptococcus and Pneumocystis jiroveci infections. Fungal pneumonias are treated with anti-fungal medications.

Pneumonia Risk Factors

Anybody can get pneumonia. But the people who are particularly at risk for developing serious complications from the disease are individuals aged 65 and over, and infants and toddlers under two years older. 

Other individuals who have a greater than normal chance of falling ill with pneumonia are smokers, heavy drinkers, people who are malnourished, and people who have been diagnosed with cystic fibrosis, asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, diabetes, heart failure, or sickle cell anemia. Stroke victims who have difficulties clearing their lungs by coughing up secretions also are at risk for developing the disease.

If your immune system is weakened secondary to corticosteroid medication regimens or certain diseases such as HIV, you also have a much greater likelihood of developing pneumonia than the general population.