What is Pneumonia ?

The typical signs and symptoms in children under five are fever, cough, and fast or difficult breathing.

Fever is not very specific, as it occurs in many other common illnesses and may be absent in those with severe disease, malnutrition or in the elderly

In addition, a cough is frequently absent in children less than 2 months old. More severe signs and symptoms in children may include blue-tinged skin, unwillingness to drink, convulsions, ongoing vomiting, extremes of temperature, or a decreased level of consciousness

Bacterial and viral cases of pneumonia are usually present with similar symptoms. Some causes are associated with classic, but non-specific, clinical characteristics

Pneumonia caused by Legionella may occur with abdominal pain, diarrhea, or confusion.

Pneumonia is an infection of the lung. The lungs fill
with fluid and make breathing difficult. Pneumonia
disproportionately affects the young, the elderly, and
the immunocompromised. It preys on weakness and
vulnerability.

Pneumonia caused by Streptococcus pneumoniae is associated with rusty colored sputum. Pneumonia caused by Klebsiella may have bloody sputum often described as "currant jelly".

Bloody sputum (known as hemoptysis) may also occur with tuberculosis, Gram-negative pneumonia, lung abscesses and more commonly acute bronchitis.

Pneumonia caused by Mycoplasma pneumoniae may occur in association with swelling of the lymph nodes in the neck, joint pain, or a middle ear infection.

. Pneumonia is the world’s leading cause of death among
children under 5 years of age, accounting for 15% of all
deaths of children under 5 years old. There are 120 million
episodes of pneumonia per year in children under 5, over
10% of which (14 million) progress to severe episodes.
There was an estimated 935,000 deaths from pneumonia in
children under the age of five in 2013.

Viral pneumonia presents more commonly with wheezing than bacterial pneumonia.

3. In the US, pneumonia is less often fatal for children, but
it is still a big problem. Pneumonia is the 1 most common
reason for US children to be hospitalized

Pneumonia was historically divided into "typical" and "atypical" based on the belief that the presentation predicted the underlying cause.

However, evidence has not supported this distinction, therefore it is no longer emphasized.

. For US adults, pneumonia is the most common cause of
hospital admissions other than women giving birth. About 1
million adults in the US are hospitalized with pneumonia every
year, and about 50,000 die from this disease

Pneumonia is due to infections caused primarily by bacteria or viruses and less commonly by fungi and parasites.

Although there are over 100 strains of infectious agents identified, only a few are responsible for the majority of the cases.

While young healthy adults have less risk of pneumonia
than the age extremes, it is always a threat. Half of all
non-immunocompromised adults hospitalized for severe
pneumonia in the US are younger adults (18-57 years of
age). Half the deaths from bacteremic pneumococcal
pneumonia occur in people ages 18-64

Mixed infections with both viruses and bacteria may occur in roughly 45% of infections in children and 15% of infections in adults.

Older people have higher risk of getting pneumonia,
and are more likely to die from it if they do. For US
seniors, hospitalization for pneumonia has a greater risk
of death compared to any of the other top 10 reasons for
hospitalization

A causative agent may not be isolated in approximately half of cases despite careful testing.

The term pneumonia is sometimes more broadly applied to any condition resulting in inflammation of the lungs (caused for example by autoimmune diseases, chemical burns or drug reactions); however, this inflammation is more accurately referred to as pneumonitis.

Pneumonia is the most common cause of sepsis and
septic shock, causing 50% of all episodes.

Factors that predispose to pneumonia include smoking, immunodeficiency, alcoholism, chronic obstructive pulmonary disease, asthma, chronic kidney disease, liver disease, and old age

Pneumonia can develop in patients already in the
hospital for other reasons. Hospital-acquired pneumonia
has a higher mortality rate than any other hospital-acquired
infection.