Infectious causes?
Professor Leonard Jason and colleagues at the Centre for Community Research, DePaul University, Chicago, recently published a paper in the journal Chronic Illness, exploring ME/CFS patients’ perceptions of possible infectious causes for their illness. The objective of this study was to identify self-reported infectious illnesses associated with the onset of the disease. These are possible infections not confirmed by medical tests.
We often hear that ME/CFS is linked to a range of possible infectious agents, principally Epstein-Barr virus (EBV) and Human Herpes Virus (HHV), but most ME/CFS sufferers do not have a confirmed laboratory diagnosis of EBV or HHV. Many patients therefore receive a diagnosis of post-viral fatigue syndrome, ME/CFS or medically unexplained symptoms, and are often left to speculate as to the possible triggers for their illness.
Patient reports
In this study, Prof. Jason and colleagues examined data from multiple sites (9 cohort samples) in several countries, including information on 1,773 individuals diagnosed with either ME, CFS or ME/CFS. This information included qualitative data on infectious triggers, which the researchers coded and classified for analysis.
Nearly two-thirds of patients (60.3%) reported an infectious illness some time before the onset of their ME/CFS. The most frequently reported infectious illness was mononucleosis (triggered by EBV), which accounted for 30% of infections. However, more than one hundred other infectious illnesses were mentioned by patients.
The table below summarises many of the most commonly reported triggers of ME/CFS in this group of patients.
| Mononucleosis | 21.05% |
| Flu/flu-like illness | 19.08% |
| Epstein-Barr virus | 7.20% |
| Cold | 6.17% |
| Sinus infection | 4.58% |
| Pneumonia | 3.37% |
| Varicella zoster virus | 2.53% |
| Bronchitis | 2.53% |
| Borreliosis | 2.34% |
| Gastroenteritis | 2.25% |
| Upper respiratory infection | 2.15% |
| Cytomegalovirus | 2.06% |
| Strep throat | 1.87% |
| Ear infection | 1.40% |
| Respiratory infection | 1.40% |
| Mycoplasma pneumoniae | 1.40% |
| Throat infection | 1.31% |
| Dental infection | 1.31% |
What does this mean?
There are a couple of interesting findings from this study. The first is that patients in different countries differed in their perceptions, with just 24% of the Spanish sample indicating an infectious trigger, compared with 74% of patients from Norway. The researchers were unable to explain the international discrepancy, which may be due differences in measurement methods.
Second, the almost 100 different infections reported range from EBV at the top, to dental infections (gingivitis), bone infection (osteomyelitis), and skin infection (cellulitis) at the bottom of the prevalence pyramid. We might overlook the possible role of lesser reported infections in ME/CFS causation, but common dental infections can trigger more serious illnesses, such as Infective Endocarditis, an infection caused by bacteria that enter the bloodstream and settle in the heart lining or valves.
Therefore, we cannot discount any infections, but should continue to direct research resources towards investigating those most commonly reported, such as Mono, EBV and flu/colds. We must also consider the possibility of overlapping infections, one on top of another – flu with EBV for example.
Finally, we must note that patients in this study may not know what infection triggered their ME/CFS. There is a degree of recall bias at work here, and it is unfair to expect any patient to be able to identify the exact infection that played a role in their ME/CFS presentation. This study really points scientists in a certain direction, and the signposts continue to point to EBV and other viral infections.
This is the reason ME Research UK continues to invest in innovative research that explores the link between EBV exposure and ME/CFS, and the possible role EBV plays in the disease.
