Final answer:
Constrictive pericarditis in the developing world is most commonly caused by rheumatic fever, which is an immune response to infection with Streptococcus pyogenes. This condition leads to a thickened and scarred pericardial sac, impairing heart function. Treatment often involves antibiotics or surgical removal of the pericardium.
Step-by-step explanation:
The most common cause of constrictive pericarditis in the developing world is often related to infectious diseases, with rheumatic fever being a significant contributor. Rheumatic fever is an autoimmune response to infection with the bacterium Streptococcus pyogenes, and while it primarily affects children, it can lead to chronic heart conditions, including constrictive pericarditis, later in life. This condition can also arise from various other infections such as those caused by other bacteria, viruses, fungi, or eukaryotic parasites.
Constrictive pericarditis results when the pericardial sac becomes thickened and scarred, leading to decreased heart function. Treatments may vary based on the underlying cause but could include antibiotics for bacterial causes or more involved interventions such as the removal of the pericardium in severe cases.