Causes of pleurisy

Pleurisy is inflammation of the pleura. It’s usually caused by another condition, such as an infection, but sometimes no cause can be identified.

The pleura are two thin sheets of tissue that separate the lungs and ribcage. One is attached to the ribcage and the other is attached to the lungs.
Between the pleural sheets is a thin layer of liquid that lubricates the pleura, helping to reduce friction when you breathe in and out.

When there’s inflammation, the surfaces of the two layers can become rough and the fluid 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 responsible.

Viruses known to cause pleurisy include:
the influenza (flu) virus
the Epstein-Barr virus – which causes glandular fever
cytomegalovirus (CMV) – a common virus found in most people, which doesn’t usually cause any noticeable symptoms
parainfluenza – the virus that causes the childhood condition croup

In some cases, pleurisy is caused by bacteria, such as:

streptococcal bacteria – often associated with pneumonia, throat infections and some types of skin infections, such as impetigo and cellulitis

staphylococcal bacteria – often associated with skin infections, food poisoning and, more seriously, blood poisoning (sepsis)

Meticillin-resistant Staphylococcus aureus (MRSA) can cause pleurisy, especially in hospital patients. MRSA is a type of bacteria with a resistance to a number of commonly used antibiotics.

Other possible causes of pleurisy include:

injury – if the ribs are bruised or fractured, the pleura can become inflamed

pulmonary embolism – a blood clot developing inside the lungs

sickle cell anaemia – a blood disorder that usually affects people of African or Caribbean descent

chemotherapy and radiotherapy

HIV or AIDS

lung cancer

mesothelioma – a type of cancer caused by inhaling asbestos

Autoimmune conditions, such as rheumatoid arthritis and lupus, are other possible causes of pleurisy. In these conditions, something goes wrong with the immune system (the body’s natural defence against infection and illness) and it begins to attack healthy tissue.

G Mohan