What are the causes and symptoms of pneumonia?
The list of organisms which can cause pneumonia is very large, and includes nearly every class of infecting organism: viruses, bacteria, bacteria-like organisms, fungi, and parasites (including certain worms). Different organisms are more frequently encountered by different age groups. Further, other characteristics of an individual may place him or her at greater risk for infection by particular types of organisms: • Viruses cause the majority of pneumonias in young children (especially respiratory syncytial virus, parainfluenza and influenza viruses, and adenovirus). • Adults are more frequently infected with bacteria (such as Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus). • Pneumonia in older children and young adults is often caused by the bacteria-like Mycoplasma pneumoniae (the cause of what is often referred to as “walking” pneumonia). • Pneumocystis carinii is an extremely important cause of pneumonia in patients with immune problems (such as pati
