Though the definition of chronic fatigue syndrome (CFS) has changed multiple times over the last decade, in a majority of cases, the symptoms should be present for at least six months and its intensity should vary from moderate to severe for half the time. Apart from fatigue, other signs include post-exertional malaise, lack of refreshing sleep, cognitive impairment and orthostatic symptoms.
CFS is not caused or maintained by a single agent. According to several findings, psychological and physiological factors work together to make an individual prone to this condition. The assessment and treatment for CFS must be multidimensional and be customised as per the needs of the patient. Inputs sought from multiple medical specialities can help improve the quality of life of those suffering from CFS.
While CFS mostly affects young to middle-aged adults, some cases in children have also been recognised. Older adults may also suffer from this condition. However, the already existing medical conditions among them preclude the consideration of CFS in the seniors. CFS is twice as common in women than men.
A lot of effort has been made to investigate the possible causes of CFS. Viruses, immune dysfunction, endocrine-metabolic dysfunction and neuropsychiatric factors can cause CFS. Considerable interest has been shown to find out if certain viruses, including Epstein-Barr virus (EBV) and retroviruses, could be responsible for causing CFS. However, no infection agent has been proven to cause CFS, although many patients attribute their symptoms to a viral infection.
In the mid-1980s, EBV was considered to be a possible cause for CFS. This was because of three observations. EBV persists for life and reactivates frequently, thereby providing the virus the biologic potential for chronic illness. Also, patients suffering from CFS were found to have higher concentration of antibodies to EBV capsid and early antigens or to lack antibodies to EBV nuclear antigens (EBNA), and each of these indicates a recent or active infection. Moreover, some patients have clearly attributed the onset of their illness to a mononucleosis-like infection. Other viruses include human herpesvirus type 6 (HHV-6), enteroviruses, Ross river virus, and Borna disease virus.
A syndrome similar to CFS can be seen in patients with Lyme disease and following Q fever. Besides infection, other proposed theories include immunodeficiency, depression, sleep deprivation, endocrine abnormalities and genetic factors.
Signs and symptoms may include fatigue, loss of memory or concentration, sore throat, enlarged lymph nodes in the neck and armpits, unexplained muscle or joint pain, headaches and extreme exhaustion lasting more than 24 hours after physical or mental exercise. Possible complications of CFS include depression, social isolation and lifestyle restrictions.
Rajagopal is consultant, infectious diseases, Aster CMI Hospital, Bengaluru.