J18: Pneumonia, organism unspecified

Pneumonia is a group of lung infections caused by various organisms including bacteria, viruses, and fungi which are not specified in particular categorization. They can be contracted from different environmental factors or they can also spread from person to person through droplets in the air when an infected person coughs or sneezes. Common symptoms include chest pain when breathing or coughing, fatigue, fever, chills, and sometimes gastrointestinal symptoms like nausea, vomiting, and diarrhea. The infection causes inflammation in the small air sacs of the lungs called alveoli, which can then fill up with fluid or pus causing difficulty in breathing. The disease progress varies widely from mild to severe, even potentially life-threatening, depending on the individual's overall health, age and the type of organism causing the infection. Pneumonia can affect people of all ages but it is particularly severe in infants, older adults, and people with other health problems.