Key points
- Infections can sometimes leave people with symptoms that last for weeks to months or longer, even after appropriate treatment.
- Similar symptoms can follow many different types of infections, but the cause is not generally known.
Causes
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.