How is pleurisy with effusion caused?

The causes of pleural effusion due to pleurisy are multifactorial. 1. Bacterial or tuberculous infection is a common cause of pleural effusion, such as infections caused by bacteria like *Streptococcus pneumoniae*, *Staphylococcus aureus*, and invasion by *Mycobacterium tuberculosis*. These infections trigger inflammatory reactions in the pleura, leading to increased exudation and accumulation of fluid. 2. Immune-mediated diseases such as systemic lupus erythematosus and rheumatoid arthritis can also cause pleural effusion through inflammatory exudation resulting from immune responses. 3. Drug-induced factors or other unknown causes may also lead to pleural exudation and fluid accumulation. Among these, bacterial and tuberculous infections are relatively common. Treatment of pleural effusion associated with pleurisy requires therapeutic measures tailored to the specific underlying cause.