Viral infections are the most common cause of myocarditis and pericarditis. These may include adenovirus, coxsackievirus, herpes virus, influenza (flu) virus, and parvovirus B19. Viruses may infect the heart muscle tissue, causing acute or chronic immune responses from the body.
Bacteria are the most common cause of endocarditis, which occurs when bacteria and blood cells form clumps, typically on the heart valves. In most developed countries Staphylococcus aureus is the most common type of bacteria that causes endocarditis. Bacteria can enter the blood during invasive medical procedures or intravenous drug use. Streptococcus bacteria can also cause endocarditis, but this is more common in less developed countries. Pericarditis caused by bacteria is rare in the United States and other developed countries.
Fungi are rare causes of myocarditis and pericarditis. Most commonly, fungal endocarditis is caused by either Candida or Aspergillus. These infections are more common in immunosuppressed patients, including those who have HIV.
