Virus
A virus is a small infectious agent that replicates only inside the living cells of other organisms. Several viruses have been associated with the onset of ME/CFS including Epstein-Barr virus (which causes infectious mononucleosis / glandular fever), enteroviruses (the putative cause of many outbreaks of epidemic myalgic encephalomyelitis), and Ross River virus.
A prospective study in Australia found that 11% of people infected with Epstein-Barr virus, Ross River virus or Q fever (a bacterial infection) met the criteria for chronic fatigue syndrome six months later.[1]
Herpesvirus[edit | edit source]
Herpesviruses are a family of DNA viruses with extremely high prevalence rates. Once a human host is infected, the infection is life-long. While generally, immunocompetent hosts are able to keep the virus in a latent state and remain asymptomatic, several of these viruses can cause symptoms if they reactivate. They can also increase the risk of autoimmune disease and cancer.[citation needed]
It is unclear whether herpesviruses associated with Chronic fatigue syndrome play an etiological role or are "bystanders" – opportunistic reactivations under a state of immune dysregulation. In the 1984 Incline village outbreak, Gary Holmes found that patients with what his team hypothesized was chronic Epstein-Barr had elevated antibody titers to Epstein-Barr virus, cytomegalovirus, herpes simplex and measles viruses than age-matched controls.[2] However, the study cohort was defined as patients who had experienced excessive fatigue between January 1 and September 15.
A prospective study of 250 primary care patients revealed a higher prevalence of chronic fatigue syndrome after infectious mononucleosis (glandular fever) when compared to an ordinary upper respiratory tract infection.[3] Anti-early antigen titers to Epstein-Barr virus were elevated in CFS patients and associated with worse symptoms.[4]
Enterovirus[edit | edit source]
Enterovirus is a genus of positive single-stranded RNA viruses. Viruses in the enterovirus genus include coxsackievirus A, coxsackievirus B, echovirus, poliovirus and rhinovirus, though only coxsackievirus B and echovirus have been linked to ME/CFS.[citation needed] Person-to-person transmission of enteroviruses occurs through fecal-oral and oral-oral routes.[5]
Enteroviruses are responsible for a range of acute infections and illnesses. They cause about 10 to 15 million infections and tens of thousands of hospitalizations each year in the United States.[6] But acute enterovirus infections can often be mild (like a common cold) or asymptomatic when contracted.[7][8]
Though normally only capable of acute infections, under certain circumstances enteroviruses can create chronic infections, and ongoing enterovirus infections have been found in ME/CFS and several other chronic illnesses in including dilated cardiomyopathy, and type 1 diabetes. Some researchers posit that such persistent enterovirus infections may be a cause of these diseases.
Effects on cellular respiration[edit | edit source]
Some viral infections may affect mitochondrial function and reduce cellular respiration. A study of poliovirus found that polio infection rapidly decreases (45% decrease) cellular oxygen consumption (and thus energy production through cellular respiration) by inhibiting succinate dehydrogenase (55% decrease in activity) and blocking mitochondrial electron transport at or between complexes I and III.[9]
See also[edit | edit source]
References[edit | edit source]
- ↑ Hickie, Ian; Davenport, Tracey; Wakefield, Denis; Vollmer-Conna, Ute; Cameron, Barbara; Vernon, Suzanne D; Reeves, William C; Lloyd, Andrew (September 16, 2006). "Post-infective and chronic fatigue syndromes precipitated by viral and non-viral pathogens: prospective cohort study". BMJ. 333 (7568): 575. doi:10.1136/bmj.38933.585764.AE. ISSN 0959-8138.
- ↑ Homes, Gary P (May 1, 1987). "A Cluster of Patients With a Chronic Mononucleosis-like Syndrome Is Epstein-Barr Virus the Cause?". Journal of the American Medical Association. 257: 2297–2302.
- ↑ White, P. D.; Thomas, J.M.; Amess, J.; Crawford, D.H.; Grover, S.A.; Kangro, H.O.; Clare, A.W. (December 1998). "Incidence, risk and prognosis of acute and chronic fatigue syndromes and psychiatric disorders after glandular fever". The British Journal of Psychiatry: The Journal of Mental Science. 173: 475–481. ISSN 0007-1250. PMID 9926075.
- ↑ Schmaling, K. B.; Jones, J.F. (January 1996). "MMPI profiles of patients with chronic fatigue syndrome". Journal of Psychosomatic Research. 40 (1): 67–74. ISSN 0022-3999. PMID 8730646.
- ↑ Alsina-Gibert, Mercè. "Dermatologic Manifestations of Enteroviral Infections (Medscape article)". Medscape.
Enteroviruses spread from person to person by either oral-oral or fecal-oral routes.
- ↑ "Non-Polio Enterovirus". CDC Website.
Non-Polio Enterovirus. Non-polio enteroviruses are very common. They cause about 10 to 15 million infections and tens of thousands of hospitalizations each year in the United States. Most people who get infected with these viruses do not get sick or they only have mild illness, like the common cold.
- ↑ Schwartz, Robert A. "Enteroviruses (Medscape article)". Medscape.
More than 90% of infections caused by nonpolio entero viruses are asymptomatic or result only in an undifferentiated febrile illness.
- ↑ Choudhary, Madhu Chhanda. "Echovirus Infection (Medscape article)". Medscape.
More than 90% of echoviral infections are asymptomatic.
- ↑ Koundouris, A (May 2000). "Poliovirus Induces an Early Impairment of Mitochondrial Function by Inhibiting Succinate Dehydrogenase Activity". Biochemical and Biophysical Research Communications. 271: 610–4.
