Chronic Symptoms Following Infections

Infections can sometimes leave people with symptoms that last for weeks to months or longer, even after appropriate treatment. Some of these symptoms are well-recognized and specific to the type of infection, for example, loss of smell and COVID-19. Other symptoms are unexplained and general (e.g., fatigue or difficulty thinking).  Similar symptoms can follow many different types of infections.  These general symptoms include:

• Tiredness or fatigue that interferes with daily life
• “Flu-like” symptoms including, muscle pain, headache, sweating, irritability, and general feelings of sickness
• Symptoms that get worse after physical or mental effort (also known as “post-exertional malaise”)
• Difficulty thinking or concentrating (sometimes referred to as “brain fog”), trouble finding words
• Chronic or recurrent joint pain
• Sleep problems

Some disease agents that have been linked to chronic symptoms

(In alphabetical order)

• Borrelia burgdorferi (bacteria causing Lyme disease)
• Campylobacter
• Chikungunya virus
• Coxiella burnetii (bacteria causing Q fever)
• Dengue virus
• Ebola virus
• Epstein Barr virus
• Enterovirus
• Poliovirus
• SARS-CoV-2 (COVID-19)
• West Nile virus

Some people with chronic symptoms following infections may not know which infection triggered the symptoms, or even recognize that they had an infection before their chronic symptoms began. People with chronic symptoms and unknown preceding infection may be diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome.

Causes of chronic symptoms following infections

It is not fully known why some people experience chronic general symptoms. Infections trigger many different responses in the human body. This makes it difficult for researchers to sort out why some people have chronic symptoms after an infection and others do not. In some cases, an infection may continue to trigger the immune system or “turn on” an autoimmune condition, where the immune system attacks healthy cells by mistake. In other cases, the body’s response to an infection might cause inflammation that may be hard to “turn off.” These immune or related inflammatory responses may cause a person to feel more pain, fatigue, or other symptoms than normal. Other responses include damage to the nervous system, changes to the microbiome (the collection of microbes, or germs, that live on and in the body), and damage to the body’s ability to produce energy from food.

Effects of chronic symptoms following infections

The type, duration, and intensity of chronic, symptoms following an infection can be different from person to person. Symptoms may come and go or vary in severity (how bad the person feels over time). Some patients’ symptoms slowly improve with time. However, it can take weeks and sometimes years to feel well. The longer fatigue or other symptoms last, the more likely they are to lead to other problems, such as physical weakness or difficulty with performing daily activities. Long-term illnesses can also impact relationships and a person’s mental health.

Addressing chronic symptoms with a healthcare provider

It is important to talk to a healthcare provider if you are concerned about any symptoms that last a long time. A healthcare provider will perform a thorough evaluation that might include a physical exam and testing to help them consider or rule-out possible causes of the symptoms. Often test results are normal, and the cause of symptoms remains unexplained. It is important for you and your healthcare providers to understand that normal test results do not mean your symptoms are not real. In some cases, tests to confirm a diagnosis do not exist. It may take a long time to consider or rule out all potential causes of chronic symptoms.

A healthcare provider may also ask questions to understand your health history, including if you had a positive test for an infection, family health history, current symptoms, and how you are able to keep up with daily activities. Speaking with your healthcare provider about the symptoms you are experiencing could help identify new medical conditions. While there are no medicines or methods that work for everyone, your healthcare provider can work with you to try methods that have helped some and could improve your symptoms and quality of life.  Researchers and healthcare providers are still learning about chronic symptoms following infections and how best to manage them and support patients.

Treatment for chronic symptoms following infections

In many cases, there are no specific treatments or cures for chronic symptoms following an infection. There are, however, steps you can take to reduce the impact these symptoms have on your life. Given the overlap in symptoms, management and treatment approaches for people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) can be helpful for people experiencing chronic symptoms.

More information on how to treat chronic symptoms following a specific infection may be available at the above disease agent links.

CDC action to address chronic symptoms following infections

Many infections can result in chronic general symptoms that look similar to ME/CFS.  CDC believes that by looking across the infections known to cause chronic symptoms, we can learn more about how often and why they occur, as well as how to diagnose and treat them. This year, CDC is:

• Funding studies to learn more about how to recognize and treat patients who experience chronic symptoms after an infection
• Meeting with experts to prioritize research activities and improve guidance for clinicians
• Increasing awareness among healthcare providers and the public
• Monitoring the occurrence of chronic symptoms following certain infections
• Working with patient partner organizations to understand the needs and priorities of people with chronic symptoms following infection