Causes of Myocarditis

Despite the fact that researches have identified a large number of causes for myocarditis, in the majority of cases the doctors are unable to find the cause of this disease. The causes also vary depending on the geographical region. For example, viruses are usually the main cause of myocarditis in North America and Europe. However, globally, the most common cause for myocarditis is Chagas’ disease, caused by the protozoan Trypanosoma cruzi.

Infections

• Viral infections, which are the main culprits behind cases of myocarditis in Europe and North America, include adenovirus, coxsackie virus, parvovirus B19, enterovirus, HIV, polio virus, rubella virus, human herpesvirus 6, cytomegalovirus, and possibly hepatitis C.
• Protozoa-caused myocarditis can be cause Trypanosoma cruzi, as mentioned above, and by Toxoplasma gondii – a wide-spread protozoan infection spread by cats.
• Bacterial myocarditis is usually caused by Actinomyces, Borrelia burgdorferi, Brucella, Corynebacterium,Tropheryma whipplei, leptospirosis, Rickettsia, and Vibrio cholerae.
• Fungal myocarditis in only caused by Aspergillus, which is represented by several hundred species of mold.
• Parasitic myocarditis is often caused by ascarids, Paragonimus westermani, Echinococcus granulosus (a disease often spread by dogs), schistosoma, Trichinella spiralis, Taenia solium, Wuchereria bancrofti, and visceral larva migrans.

It should be noted that bacterial myocarditis is quite rare in people who do not have immunodeficiency.

Toxins

The most common toxin that causes myocarditis is of course alcohol. Many people with alcoholism suffer from myocarditis caused by the toxic effects of alcohol. Other toxic substances that cause myocarditis include chemotherapy drugs, antipsychotics, and some designer drugs including mephedrone (a drug that is similar to MDMA and amphetamines).

Immunologic

Myocarditis can sometimes be caused by an allergy, for example to acetazolamide or amitriptyline. Myocarditis is also one of the complications of a heart transplant, when the body’s immune system, recognizes that the heart’s cells are foreign. In other cases, autoantigens (antigens that attack one’s own cells) can be created by the immune system, due to a certain sickness, including systemic lupus erythematosus, scleroderma, systemic vasculitis, sarcoidosis, and Wegener’s granulomatosis. Heavy metals, such as iron and copper, and various toxins, including, snake venom, carbon monoxide, and arsenic toxin, can also trigger an autoimmune reaction.

Physical agents

In some rare cases myocarditis can be trigger by electric shock and radiation. It is still debated how exactly it happens, but many researchers agree that these physical factors can alter the heart’s proteins which triggers a response from the immune system. Antibodies, which are formed as a result, attack not only the altered proteins but also the healthy ones causing an autoimmune myocarditis.