What is Infectious Myopathy?

Types of Infectious Myopathy: Viral, Bacterial & More

Infectious myopathy is a rare muscle condition that mainly causes inflammation in the skeletal muscles due to infections. These infections can be generally caused by bacteria, fungi, viruses, or parasites. While it’s less common than other muscle diseases, such as dermatomyositis or polymyositis, infectious myositis can become serious if not treated early.

Infectious myositis is directly caused by an invading pathogen. This is distinct from autoimmune myositis, where the immune system mistakenly attacks muscle tissue, though infections can sometimes trigger an autoimmune response. This can happen through the bloodstream, after an injury, or when an infection spreads from nearby areas.

Understanding the cause, detecting symptoms early, and getting proper medical care are essential to managing this condition effectively!

What are the Different Types of Infectious Myopathy?

Infectious myopathy can be caused by different types of germs, including bacteria, parasites, viruses, and fungi. Each type affects the muscles differently depending on the source of infection.

Here are some of the main types:

1. Bacterial Myositis: It is most often caused by Staphylococcus aureus or Streptococcus bacteria. In rare cases, bacteria like E. coli or Pseudomonas may also cause infection.
2. Viral Myositis: This is commonly linked to flu viruses, especially influenza A and B. Other viruses that can cause infectious myopathy include HIV, Coxsackievirus, and Epstein-Barr virus.
3. Parasitic Myositis: It is generally caused by parasites such as Trichinella spiralis (trichinosis) or Toxoplasma gondii. This type is more common in areas with poor hygiene or unsafe food handling.
4. Fungal Myositis: This type is usually seen in people with weak immune systems and is caused by fungi like Candida or Aspergillus.

Each type requires different treatment, so identifying the cause is essential to recovery.

What Causes Infectious Myopathy?

Infectious myopathy can develop in several ways. Here are some of the main causes of this disease:

• Bacterial Infections : It is one of the most common causes of infectious myopathy. Bacteria can enter muscles through wounds or injuries or spread from another infected area and can also occur after surgery or from drug injections.
• Viral Infections : Some viruses inflame muscles directly or trigger the immune system. Flu-related myositis is common in children and usually goes away on its own. Moreover, long-term infections like HIV may cause repeated episodes.
• Parasitic Infections : It is generally caused by eating undercooked meat, especially pork infected with parasites like Trichinella.
• Fungal Infections : This is seen in people with weak immune systems. Common fungi mainly include Candida and Aspergillus, especially in those with HIV or cancer or who are on chemotherapy.

What are the risk factors for infectious myopathy?

Certain health issues and habits can raise your risk of getting infectious myositis, including:

• Muscle injuries or trauma
• Recent surgery or medical procedures
• Poor hygiene or eating contaminated food
• Weak immune system (due to HIV/AIDS, cancer, diabetes, etc.)

What are the symptoms of infectious myositis?

The main symptoms of infectious myositis can vary based on the type of infection causing the condition and the patient’s overall health. Some people may have only mild symptoms, while others may face more serious issues. Here’s what to look out for:

Localised Symptoms (Affecting One Area)

These are the symptoms that generally appear around the infected muscles:

1. Muscle pain, swelling, and tenderness in the affected area
2. Redness or skin that feels warm to the touch
3. Difficulty moving the muscle due to pain

Systemic Symptoms (Affecting the Whole Body)

These symptoms may affect your general health and energy:

1. Fever and chills
2. General sense of being unwell
3. Feeling weak or unusually tired (fatigue)

In Severe Cases

Sometimes, infectious myositis becomes serious and requires quick medical help:

1. Pus-filled pockets (abscesses) in the muscle
2. Necrotising Fasciitis – a fast-spreading, dangerous infection that requires emergency treatment

How is Infectious Myopathy Diagnosed?

Diagnosing infectious myopathy early is important to start the right treatment. Doctors usually use a mix of physical checks, lab tests, and scans. Here’s what the process may include:

• The healthcare provider will check for muscle pain, swelling, and how well you can move the affected area. They may also look for signs of infection, like fever or a fast heartbeat.
• Blood tests may be done to look for high white blood cells, which show infection. Other tests, like CRP or ESR, help check inflammation levels, and high creatine kinase (CK) levels may show muscle damage.
• Blood samples or a small sample from the muscle might be tested under a microscope to find the exact germ causing the infection.
• Imaging tests such as MRI or ultrasound help detect muscle swelling, abscesses, dead tissue, or pockets of pus.

How is Infectious Myopathy Treated?

Treatment of infectious myopathy mainly depends on the cause of the infection and its severity. The primary treatment for bacterial pyomyositis with abscess formation is surgical drainage or aspiration. Doctors usually combine medication with supportive care to help you recover fully, such as:

• In bacterial cases, antibiotics are given—first broad-spectrum types, then adjusted once test results identify the exact germ.
• For viral infections, treatment usually involves rest and symptom relief. Antiviral medicines are only used in certain long-term cases, like HIV.
• If a parasite is the cause, doctors may prescribe antiparasitic medications like mebendazole or albendazole.
• Fungal infections are treated with antifungal drugs such as amphotericin B or fluconazole, especially for patients with weak immune systems.
• Pain relief with NSAIDs or acetaminophen, along with rest and physical therapy, helps ease discomfort and rebuild muscle strength.
• In serious cases, surgery may be required to drain pus or remove dead muscle tissue.

What is the outlook and recovery period for infectious myopathy?

Most people recover well if the infection is detected and treated early. However, waiting too long can lead to permanent muscle damage or even life-threatening issues.

Additionally, the factors that affect recovery include how quickly treatment starts, your overall health, and the type of infection.

Infectious myopathy may be rare, but it can become serious if ignored. Since it can be caused by viruses, bacteria, parasites, or fungi, getting the right diagnosis and treatment early is essential.

If you notice muscle pain, swelling, or a fever that doesn’t go away, don’t wait—consult a doctor right away. Acting fast can help you recover completely and avoid unnecessary complications.

Also Read:

→ How Do You Treat Mitochondrial Myopathy

→ What are the Types of Inflammatory Myopathy

→ What is the Best Treatment for Necrotizing Myopathy

→ Best Treatment for Myopathy

→ What is Congenital Myopathy