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What is pneumonia? Key things to know

Image: MGN Online

Image: MGN Online

(CNN) — After Democratic presidential candidate Hillary Clinton fell ill during a 9/11 commemoration ceremony on Sunday, Clinton’s physician revealed that she was diagnosed with pneumonia on Friday and is being treated with antibiotics.

CNN Chief Medical Correspondent Dr. Sanjay Gupta said that although pneumonia is treatable, “it’s a serious diagnosis still, and is something that should not be taken lightly.”

Here are the key things to know about the infection.

What is pneumonia?

Pneumonia is a respiratory infection that affects the lungs, resulting in inflammation of the alveoli — the air sacs that make up the bulk of the lungs and help us breathe. Infection causes them to fill with fluid or mucus, limiting the amount of oxygen entering the sacs and making it painful to breathe.

There are many types of pneumonia, caused by different forms of infection, and the effects on the body range from mild to severe. Children are vulnerable, with pneumonia being the single biggest cause of infectious death in children worldwide, according to the World Health Organization.

What causes it?

Pneumonia is most commonly caused by bacteria or viruses, but it can also be caused by fungi.

In the United States, the Centers for Disease Control and Prevention say common causes of viral pneumonia are “influenza and respiratory syncytial virus (RSV), and a common cause of bacterial pneumonia is Streptococcus pneumoniae (pneumococcus).”

Another common bacterial cause of pneumonia is infection with bacteria Haemophilus influenzae type b (Hib), which also causes meningitis. Vaccines are available against the bacterial forms of infection, as well as influenza, and can help protect individuals from infections that could lead to pneumonia.

What are the symptoms?

According to the American Lung Association there are several telltale signs of pneumonia:

Cough, which might be accompanied by greenish, yellow or bloody mucus
Fever, ranging from mild to high
Shaking chills
Shortness of breath, which might only occur when you climbs stairs

Less common pneumonia symptoms include:

Sharp or stabbing chest pain that gets worse when you breathe deeply or cough
Headache
Excessive sweating and clammy skin
Loss of appetite, low energy and fatigue
Confusion, especially in older people

Other less common symptoms can include nausea, vomiting, wheezing and joint and muscle pain, according to the UK’s National Health Service.

Is it contagious?

Pneumonia can be spread in multiple ways. The viruses and bacteria are typically contracted by people breathing them into their lungs, then spread through airborne droplets when people sneeze or cough. It can also spread through blood, according to the WHO.

Atypical pneumonia can be caused by several types of bacteria, including Legionella pneumophila, mycoplasma pneumoniae and Chlamydophila pneumoniae, and can be passed from person to person.

Aspiration pneumonia infections can occur if you inhale food, drink, vomit or harmful substances, such as smoke or chemicals, into your lungs.

Pneumonia can spread in hospital or other health care environments.

Who is most at risk?

Older adults, children and people with chronic disease are at risk. A weakened immune system, particularly in children (often the result of malnutrition, undernourishment or other pre-existing illnesses), can increase the risk of infection.

Can it be fatal?

In the United States, about 50,000 people die from pneumonia every year, according to the CDC, although many deaths could be prevented with vaccines or treatment.

Globally, pneumonia makes up 15% of all deaths among children under 5 years of age, with more than 920,000 deaths reported in 2015, according to WHO.

But adult and child deaths from pneumonia vary greatly by country. In the United States, there were 101 deaths from pneumonia for every million deaths between 2001 to 2010 and 214 deaths per million in the UK, according to the British Lung Foundation. In the same time period in South Africa, there were 1,168 pneumonia deaths per million.

How is it treated?

Treatment depends on the type of infection and its severity. Mild infections can be treated at home with plenty of fluids, rest and by controlling fevers with medication, according to the American Lung Association.

Bacterial infections can be treated with a range of antibiotics, including azithromycin, amoxicillin and erythromycin. For viral infections, antivirals are sometimes prescribed. Clinton’s physician announced that she is currently on antibiotics, meaning she must have a bacterial form of infection.

Can it be prevented?

There are several vaccines that can be helpful in preventing diseases that cause pneumonia, including whooping cough, influenza, measles and pneumococcal disease. Improving respiratory health by quitting smoking will help lungs stave off infection.

Other ways lessen the risk of contracting the disease? Washing your hands after you use the bathroom, change a baby’s diaper or blow your nose, and before and after handling or preparing food, along with generally maintaining good hygiene.