In strict medical terms, the name Chronic Fatigue Syndrome (CFS) refers only to a pattern of symptoms (see below). It can't be called a disease because there's no medical test that can link all cases (like the HIV test does in AIDS). But many people believe CFS is one illness because so many cases are so similar.
There are four main categories of symptoms in CFS:
- Fatigue: People with CFS experience profound, overwhelming exhaustion, which gets worse after exertion and can never be fully relieved by sleep.
- Pain: Pain in CFS includes muscle pain, joint pain, headaches, stomachaches, lymph node pain, and sore throats.
- Cognitive Problems and Neurological Problems:
- Cognitive Problems: People with CFS have trouble remembering words, names, and places, find it hard to concentrate, and have trouble thinking straight.
- Neurological problems include dizziness and light-headedness, especially when standing up quickly.
- Sensitivies: People with CFS tend to be sensitive to light, sound, and some chemicals and foods.
Some cases of CFS start gradually, but the majority start suddenly, often triggered by the flu or some other illness. People with CFS may get better after a few years or many years or may not get better at all. No one is sure whether anybody is truly cured or whether their illness has just subsided enough for them to live a more normal life.
Some people are more limited than others. The sickest are housebound, while some people are self-reliant, and some are able to work or attend school. Some people with CFS can push themselves to do extraordinary things but feel much worse afterward.
Diagnosing CFS is very difficult. There is no conclusive test for CFS, so doctors must rely on their experience and intuition. However, some doctors are not familiar with CFS and some refuse to diagnose it. This situation is rapidly changing, with more doctors willing to diagnose it and more diagnoses each year.
Studies estimate that there are between 75 and 420 cases per 100,000 adults in the U.S. This comes to between 200,000 and 1,000,000 adults with CFS. Between 60% and 85% of these people are women. Adolescents and children also get CFS, possibly less often than adults.
There are some illnesses so similar to CFS that it is hard to distinguish between them. People with Fibromyalgia have muscle pain and sleep disturbances. Those with Multiple Chemical Sensitivities (MCS) are sensitive to chemicals and have sleep disturbances. Many veterans with Gulf War Illness (GWI) have symptoms almost identical to CFS.