Racaniello on possible CFS Etiology

Why have investigators failed to identify a virus behind CFS? (It is not due to the lack of appropriate technology; this has improved substantially since the 1980s with the development of polymerase chain reaction and rapid DNA sequencing.)

One explanation for this dilemma is that an infectious agent does not cause CFS.

However, there is plausible evidence for an infectious etiology, including observations that the disease is known to occur in outbreaks. Furthermore, in many cases the onset of symptoms appears to begin with a flu-like illness.

Additionally, CFS is a heterogeneous disease, and may be caused by several different agents or a combination of viruses and non-infectious conditions.

Another possibility is that an infection initiates an immune response that spirals out of control, leading to CFS symptoms. This scenario implies that at least some CFS patients have underlying deficits in immune regulation. If that’s true, it will be very difficult to identify the virus involved because it will likely have been eliminated from patients’ systems by the time CFS symptoms become apparent.

In retrospect, it is clear that the properties of AIDS made it an easy disease to understand. While the path to understanding CFS has been clouded by non-scientific issues, in the end the main reason why we do not understand this disease is because it is extraordinarily complex. But that never stopped a good scientist.