- Last Updated: 25 November 2015 25 November 2015
Infectious agents linked to CFS
Dr. Komaroff listed a number of infectious agents and illnesses that have been linked to CFS:
Epstein Barr virus: A minority of CFS patients develop CFS after an initial infection with Epstein Barr virus (This can include people who come down with mononucleosis, who instead of getting well after 3-6 months, become chronically ill with CFS.)
Q-fever: People can develop CFS after coming down with Q-fever. This illness normally occurs in farming communities where the Q-fever bacterium most often lives.
Ross River virus—Ross River virus is an RNA-virus endemic to Australia and South Pacific Islands that causes the mosquito-borne illness Ross Valley fever.
Lyme Disease: Lyme Disease is a bacterial infection (B burgdorferi). Dr. Komaroff stated that Lyme Disease “can lead to CFS.”
Parvovirus can lead to CFS. Dr. Komaroff stated, “We published a paper a month ago, mainly work by Jonathon Kerr, which shows this pretty nicely.”
Enteroviruses are another group of viruses, which he believes have been linked to CFS.
CFS may be linked to Borna disease virus, but this linkage is not at all solid.
Human Herpes Virus-6 (HHV-6): Dr. Komaroff and his associates have spent decades studying this virus and its association with CFS. More on the role of this virus with CFS will be discussed below.
Xenotropic Murine leukemia-related retrovirus (XMRV): In October 2009, the journal Science published an important paper about the possible association of this retrovirus with CFS. More on this possible association will also be discussed below.
The 2006 Australia prospective study (Hickie I., et al.)
This study organized by the U.S. Centers for Disease Control and Prevention (CDC) was conducted in a very small, remote farming community in Australia in which there was only a small group of doctors, one hospital, and one medical laboratory.
“People lived in that community, got their medical care there, you could follow what happened to every single person in that community who got a particular type of infection—and you knew you could follow every single person in the study for several years. There are not many places you could do such a careful study.”
[Editor Note: Many CFS studies are not able to study patients from the time they first became ill, and therefore can only utilize medical and lab records, as well as patients’ and doctors’ memories as to the natural history and pathophysiology of the illness as it developed. This type of study is called a retrospective study. The Australian study was a prospective study, meaning that the patients’ illnesses could be watched and measured from the very beginning; moreover, the patients were known before they became ill, so that further objective conclusions could be drawn.]
This study consisted of 256 patients who had come down with 3 different infectious illnesses. The patients were followed from the date they became ill for one year (in the first report).
The 256 patients had acute laboratory-identified EBV, Q-fever, or Ross River virus infections. 11% of the entire group developed CFS. In fact, 11% of patients in each virus group came down with CFS—the same percentage with each of the very different infectious agents.
CFS was more likely to occur in the people “whose illness was most severe initially, and who were producing these cytokines.” Cytokines are the immune system chemicals which assist the immune system in fighting the infectious agent. Dr. Komaroff stated that these cytokines, in his judgment, are very likely the cause of CFS symptoms.
Depressed patients no more likely to develop CFS than non-depressed patients in the Australian study
A major benefit of the Australian study was that the psychology of the patients could be studied, both before they got sick, and after they became ill with CFS.
The study could not find any psychiatric factors or demographic factors that made people more likely to develop CFS.
Some people who had a history of depression before they became sick did go on to develop CFS. But patients, without prior history of depression, who developed one of these infections, also sometimes went on to develop CFS.
In fact, people without a prior depression developed CFS just as often as patients who had a prior depression. “So no psychiatric link could be found.” The lead researcher, Dr. Ian Hickie, was himself a psychiatrist.
The study was very effective by showing that CFS could follow an infection with a virus, and that those who developed CFS were initially more ill than the other patients. And, that there was no psychiatric link between CFS and pre-existing psychiatric illness.
Enterovirus infection and CFS
Dr. John Chia in Los Angeles has done much of the research on the role of enteroviruses in CFS. Dr. Chia has biopsied the lining of the stomach in patients with CFS—typically patients with a lot of stomach symptoms. He has found enteroviruses in the lining of the stomach much more often in people with CFS than in healthy controls.
Study results—(refer to slide, Enteroviral Infection in CFS: Gastric Antrum Biopsy Positive) demonstrated that 135 of 165 (82%) of CFS patients had enteroviral infection in the lining of the stomach as opposed to 7 of 34 (20%) healthy controls (p<0.001).
Dr. Komaroff noted these study results were “fairly persuasive”, but at this time, it is not yet known whether these enteroviruses had caused the illness.