The Lyndonville Journal:

Symptom Variation: Illness or Host?

David S. Bell, MD, FAAP

Published in Lyndonville News, November 1999

Roughly 70% of the persons I see in the office have a pattern of symptoms that is "typical of" CFS. The remaining 30% have variations where doubt can be raised as to the diagnosis. This variation in symptoms is the main reason that most researchers see CFS as a variety of differing illnesses that produce fatigue as a symptom. Part of this is because of the current accepted definition of CFS, the CDC research criteria.

These research criteria for CFS are just that - research criteria. They were not designed to help the clinician make the day to day diagnosis of CFS in the office. These criteria are intentionally restrictive. The purpose of this restriction is to create a small but homogeneous group of persons with a homogeneous symptom pattern that permits research. Without a good restrictive definition, it is impossible for one researcher to know what another is talking about in the medical literature.

Unfortunately, this creates a big problem. Many clinicians, insurance companies, and governmental disability people will say that if you do not fit the research criteria you cannot have CFS. I do not think this is true. I know of many persons with CFS symptoms who do not fit the research criteria but are disabled. Clinical criteria for the practicing clinician need to be developed, but because of the political complexities, that will have to be delayed for a while.

Is CFS one illness or many? Obviously this question cannot be answered at the present time, and the debate continues. But I feel that the vast majority have a single illness, rather than CFS being a mish-mash of a hundred or so different illnesses. The issue here is the debate of illness versus host. What exactly comes from the cause, and what comes from the host response? To look at this conflict, let us look at chicken pox.

Chicken pox is an everyday, run of the mill, simple illness. Every clinician makes the diagnosis with ease. You see one chicken pox, you have seen a thousand. It is simple and it is one single illness. That is because it is an illness that affects a distant target organ - the skin. A five-year-old comes in with a fever and little blisters that look like a "dew drop on a rose petal". And that is exactly what a perfect chicken pox looks like (I have no idea where the chicken part comes in).

There may be some minor variations. A child may have thirty pox or three hundred. Some pox (or poxes?) may get infected or scabbed over. Big deal, it is still chicken pox, one illness. The host (or person with the illness) does not affect it much. But wait. In some cases the host is critical and the illness can be different. Some people have chicken pox without a rash, or have a pneumonia, or worse yet, have a neurologic complication. Is it still chickenpox? Yes because we are able to culture the virus from the lung or brain and it is the same as the regular chicken pox in the skin.

In CFS we do not have this luxury; the situation is different. Whatever CFS is, it affects a very central mechanism within the body, not an end organ like the skin. And this central mechanism, probably the brain, can manifest the symptoms of an insult very differently. With the brain, the same injury or illness causes a variety of symptoms. (Brain tumors, for example. The symptoms of a one-inch area of brain injury depend entirely upon the location of this injury. In one area, there may be minor if any symptoms. In another it might cause arm weakness, in another area, behavior or emotional symptoms).

Let us suppose for one minute that a single neurotropic virus, one that affects brain tissue causes CFS. If this virus affects only a small part of the brain, the symptoms will be uniform (post-encephalitic Parkinson's). But if it affects more than one area, then a multitude of symptoms may result, with clear variations from person to person (Post polio syndrome). The issue is the competition between agent specificity and how the host responds to it (host versus illness).

The enormous complexity of both genetic and environmental factors makes people different. By itself, this is an interesting discussion, and probably a good thing. But science would be easier if we were all clones. (We would probably get along better as well.) But the complexity of host response, differences in immunity, emotional vulnerability, and environment makes it so that the same injury may cause a variety of responses, particularly if that injury is a central or primitive part of the brain.

In CFS, we can trace the symptoms to this primitive part of the brain where hormones are produced, where sleep and alertness are regulated, where blood pressure and heart rate are controlled, where pain is modified. One person with CFS may have asthenia as the worst symptom. Another pain is the worse symptom. Are these two illnesses or are they the same? The answer is seen not by looking at one or two symptoms, but by examining the entire symptom pattern.

For now, it is reasonable to define CFS broadly without being picky. A clinical, symptom based diagnosis is appropriate, with the understanding that other fatigue causing illnesses have been excluded. The pattern of symptoms rather than the specific worst symptom defines the diagnosis. And this pattern may vary from person to person. I do not see this variation as due to differing illnesses. Rather I see the same illness having differing host responses.

The roots of my bias are easy to spot. In Lyndonville, many persons developed severe fatigue and other symptoms due to something. Because this took place in an isolated rural community, I feel that it must have been a single event. I do not think that fifteen different causes of CFS hit all at the same time. For this reason, the variation of symptom severity and even emphasis must be due to host responses rather than cause. Two children in the same family become ill. One has acute onset, one gradual; one with fatigue as the worst symptom, one with headache. But it is too much of a coincidence that these would be different illnesses within the same family at the same time.

As an aside, the CDC has stated that CFS does not run in families. This is because all may not fit the CDC research criteria. But most clinicians feel that there is a clear familial component. If three family members develop chronic fatigue at the same time, host response is more likely to explain the differences in symptoms than the possibility of separate illnesses. At the time of the CFS "outbreak" in Lyndonville, there were those with viral infections that caused two months of fatigue. Lucky individual. And there were siblings who got full-blown CFS. My hunch is that it is the same initiating event expressing itself differently in separate individuals.

We will know the answer to host versus illness only when an underlying cause is known in a few persons. Then we can see if the others have evidence of the same underlying cause. This was the case with HIV infection. Some persons would have cancer, some bad pneumonias. Only when a specific initiating event was found was it possible to understand the full spectrum of HIV infection.

So now we have to wait. We can create a definition, and start from there. It is my hunch that we will soon define appropriate subgroups of CFS. And it remains to be seen whether these subgroups are artificial or will accurately define different causes of CFS. But until this occurs, persons with CFS should not be denied appropriate diagnosis, treatment, or disability benefits if warranted. The definition of CFS now must be broad. Whether due to host response or initiating cause will be answered eventually with research. I am going to put my money on a few different initiating events causing a specific physiological injury in persons with varying host response. And I keep wondering why I am broke.

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