The pleura
The pleura is the double-layered membrane that is located between the lungs and ribcage. One layer is attached to the ribcage and the other is attached to the lungs.
The layers of the pleura are separated by a very thin layer of liquid. The liquid works like lubricating oil by reducing the friction between the layers of the pleura and allowing the lungs to expand and contract without any resistance.
If the pleura is irritated, the surfaces of the two layers can become uneven and the fluid in between them can become sticky. This can cause the layers to rub together, resulting in pain and discomfort.
Infection
An infection is the most common cause of pleurisy.
Any type of infection has the potential to spread to the pleura, but viral infections are usually to blame.
Viruses that are known to trigger pleurisy include:
- the influenza virus - both seasonal flu and swine flu
- the Epstein-Barr virus - which is the virus that causes glandular fever
- cytomegalovirus (CMV) - a common virus that is found in most people and does not usually cause any noticeable symptoms
- parainfluenza - which is the virus that causes the childhood condition called croup
The most common causes of bacterial pleurisy are:
Meticillin-resistant Staphylococcus aureus (MRSA) is a common cause of bacterial pleurisy which can sometimes affect people who are staying in hospital. MRSA is a type of bacteria that has developed a resistance to a number of commonly used antibiotics.
Other causes
Other possible causes of pleurisy include:
Autoimmune conditions, such as rheumatoid arthritis and lupus, are another possible cause of pleurisy. In these conditions, something goes wrong with the immune system and it begins to attack healthy tissue. The immune system is the body’s natural defence against infection and illness.
