Pneumonia is an acute respiratory infection affecting the lungs. The lung alveoli, which are responsible for gas exchange fill with fluid, making respiration difficult. 1.8 million children around the world die from pneumonia each year making it the leading cause of infant mortality.
Pneumonia can be caused by various pathogens (bacteria, viruses, and fungi). The most common include the Pneumococcus (Streptococcus pneumoniae), bacteria Haemophilus influenzae type b (Hib), the Respiratory Syncytial Virus, and the fungus Pneumocystis jirovec.
Transmission of pneumonia
The pathogens infect the respiratory tract and are transmitted by droplet inhalation produced by an infected person sneezing or coughing. They are also believed to be transmissible through the blood. The weakest people particularly the immunosuppressed (people with HIV or measles) are more sensitive to the disease. Passive smoking in children is also a risk factor for pneumonia.
Symptoms of pneumonia
Depending on the pathogen involved, symptoms may be more ore less severe. Fast or difficult respiration, cough, temperature, shivering, anorexia, or wheezing are usually seen however.
Treatment of pneumonia
Whereas bacterial pneumonias are treated with antibiotics, viral or fungal pneumonias are more difficult to treat. The youngest children are cared for in hospital.
Vaccines are available against the Pneumococcus and Hib. Vaccination against measles and whooping cough is also an effective means of prevention.
Pneumonia may be caused by Pneumocystis jiroveciinfection which is seen here on a lung radiograph. © Samir, Wikimedia, CC by-sa 3.0