Aetiologies – Viral

Fig 1: Transmission electron micrograph of adenovirus
Fig 2: Transmission electron micrograph of parainfluenza virus

Viruses are considered to be the most frequent cause of myocarditis in the developed world. The enteroviruses (Cocksackie A and B) are most commonly encountered and show a seasonal pattern of presentation with peaks in the spring and autumn.

Viruses can be detected by confirming a rising antibody titre or viral culture during the acute phase of the illness or by the presence of the viral genome in endomyocardial biopsy samples. It is likely that as advances in the detection of viruses from blood and tissue samples are made, more patients with a viral aetiology will be identified. Most authorities agree that since myocarditis often develops some days or weeks after acute infection, an immunologically mediated reaction occurs rather than direct attack on the cardiac muscle by the causative organism.

Immunocompromised individuals have a higher incidence of myocarditis and are more likely to be affected by cytomegalovirus.

Examples

• Cocksackie
• Adenovirus
• Influenza
• Parainfluenza
• Mumps
• Rubella
• Varicella zoster
• Epstein Barr
• Polio
• Rabies
• Cytomegalovirus
• Herpes
• Human immunodeficiency virus
• Hepatitis A,B,C and D