What is Infectious/Viral Myositis?

Simply Put

Myositis can occur after suffering a viral, bacterial, fungal, or parasitic infection, and the effects of the disease can range from mild muscle pain (myalgia) to the severest form, rhabdomyolysis in which renal failure can occur. Infectious Myositis mimics the symptoms of Polymyositis, typically impacting proximal muscles; those muscles which are close to the body’s core. These are relatively rare occurrences because muscle tissue is fairly resistant to infectious diseases.

Influenza A and B is the most common cause of viral myositis in the United States and the main symptoms include calf pain and difficulty walking. — Healthline

This is another good reason why you should get the flu vaccine annually.

Some of the familiar, of many, infections which have been connected with causing Myositis are:

  • HIV
  • Influenza, A and B
  • Epstein-Barr
  • Staphylococcus aureus (MRSA)
  • Streptococci
  • Trichinosis
  • Chikungunya Virus
  • Spirochete (Lyme disease)
  • Herpes


Treatment of Infectious, Viral, Bacterial, and Fungal Myositis is often dependent upon the type of infection, virus, bacteria, or fungus and can include steroids, antifungal and antiviral medications, antibiotics, IV fluids, and bed rest.

What is Rhabdomyolysis?

Rhabdomyolysis is caused by a direct or indirect muscle injury. It results from the death of muscle fibers and release of their contents into the bloodstream. This can lead to complications such as kidney failure which occurs when the kidneys cannot remove waste and concentrated urine. Rhabdomyolysis can even cause death, in rare cases. Prompt treatment is key and often brings a good outcome.

A bit more detail about Rhabdomyolysis

Myoglobin, a breakdown product when muscle is damaged, is related to hemoglobin. Both are proteins found in the body. Hemoglobin transports oxygen in the blood and myoglobin stores oxygen in muscles. When myoglobin is released into the bloodstream after a muscle injury, it is filtered out of the body by the kidneys. Myoglobin is toxic to the small tubules of the kidneys, therefore high levels of this protein can damage the kidneys and may result in renal (kidney) failure.

Many things can trigger rhabdomyolysis, including anything that damages muscle.

Simply Put

“Simply Put” is a service of Myositis Support and Understanding, to provide overviews of Myositis-related medical and scientific information in understandable language.

MSU volunteers, who have no medical background, read and analyze often-complicated medical information and present it in more simplified terms so that readers have a starting point for further investigation and consultation with healthcare providers. The information provided is not meant to be medical advice of any type.

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