Did you see the movie about the alien invaders that took over the bodies of their victims? Sound’s pretty silly, doesn’t it?

The alien invaders I’ll be talking about are not about to be credited with a plan to take over the world. Instead, it is simply their way to procreate. Make no mistake though; as much as the idea might scare you, there are aliens out there, waiting to take over your body. Well, at least parts of your body. They are called viruses.

For many years, science has tried to decide what exactly viruses are. First seen as poisons, then as life-forms, then biological chemicals, viruses today are thought of as being in a gray area between living and nonliving. This is because they cannot replicate on their own.

They reproduce only through occupation of a host cell, a truly living cell. Does this mean they are not truly alive? But viruses can obviously affect the behavior of their hosts profoundly. Finally, scientists are beginning to appreciate viruses as fundamental players in the history of life.

It is easy to see why viruses have been difficult to pigeonhole. They seem to vary depending on how you examine them. The word “virus” has its roots in the Latin term for “poison.” In the later years of the 1800’s, researchers realized that certain diseases were caused by particles that seemed to behave like bacteria, but were much smaller.

Because they were clearly biological themselves and could be spread from one victim to another, with obvious biological effects, viruses were then thought to be the simplest of all living, gene-bearing life-forms.

Viruses were ‘demoted’ to inert chemicals when researchers at Rockefeller University crystallized a virus for the first time. They saw that it consisted of a package of complex biochemicals, but lacked essential systems necessary for metabolic functions, which is generally considered the biochemical activity required to be called ‘alive.’

According to the description of what a viral particle is composed of, a virus seems more like a chemistry set than an organism. But when a virus enters a cell, it becomes quite active.

It induces the cell’s own replication machinery to reproduce the intruder’s genetic code, and to manufacture more viral protein. The newly created viral bits assemble and more virus are created, which also may infect other cells.

Are viruses alive? Viruses parasitize essentially all biomolecular aspects of life. They depend on the host cell for the raw materials and energy necessary for synthesis of all aspects of function, and all other biochemical activities that allow the virus to multiply and spread.

One might then conclude that even though these processes come under viral direction, viruses are simply nonliving parasites of living metabolic systems.

A seed might not be considered alive, but it has the potential for life. In this way, viruses resemble seeds more than they do living cells. They have a certain potential for life, but do not attain the more autonomous state of life. A virus fails to reach a certain critical complexity.

Approached from this perspective, viruses, though not fully alive, may be thought of as being more than inert matter. Perhaps they can be thought to verge on life. In fact, recent studies have found that one particular virus had numerous genes thought to exist only in cellular organisms.

The complexity of this virus’ genetic complement has challenged the line that was thought to exist between viruses and true cell-based life forms.

Viruses don’t all cause human disease. A possible surprise to most physicians is that most known viruses are persistent and innocuous, not pathogenic (disease-causing). Some types can take up residence in cells, where they may remain dormant for long periods, or take advantage of the cells’ replication apparatus to reproduce at a slow and steady rate.

Yet, many human diseases are the result of a viral infection. Unfortunately, we have few cures for this class of illness. Symptoms can be relieved, and your local pharmacy has a plethora of these, but ‘antibiotics’ that can directly kill or treat the infection are few.

Many types of disease are the result of a viral infection, including the common cold, the flu, and many others. Some of these are quite severe, while many others lead to a life-long infection, since the body is unable to rid itself of the invading organism. Since the virus is well-hidden, residing inside the host’s cells, it is challenging for the human body to identify and fight off the viral particle. Viruses can affect many areas in the body, including the reproductive, respiratory, and gastrointestinal systems. They can also affect the liver, brain, and skin. Research has revealed that viruses are implicated in many cancers as well.

Disease-causing viral infections are transmitted in numerous ways. Some are picked up via respiration. Examples include the flu and common cold. Others from a particular type of contact, kissing, and others from another type, sexual. One that I am particularly well aware of is from physical contact. Specifically, the common, everyday wart.

This is a skin disease which occurs in adults as well as children. When occurring on the bottom of the foot, the pressures of weight bearing cause this kind of growth to go into the foot, providing poor access for topical medicines. These are resistant little devils, with many treatments available. (Often in medicine, this means none of them is clearly better.)

Beyond the old standard methods of treatment such as acid, or cold, application, a particular favorite is a blistering agent, which causes the outer layers to come loose, a surprisingly comfortable method. Two different anti-cancer drugs have a fairly good success rate in treating plantar warts. (‘Plantar’ is a term referring to the bottom surface of the foot.) Sometimes the involved area of skin can be removed, precisely and accurately, with the use of a device which uses high intensity radio-waves to cut tissue.

Although a good alien invasion movie can give you a good scare, too much information about the microbial world we live in can be frightening as well. Unfortunate or not, viral organisms are part of our planet, in all its diversity. The diseases caused by some viruses can be dangerous, while others are not.

But clearly there is much we do not know about viral organisms, or the diseases they cause. Research continues, but, for now, controlling your exposure is a good philosophy (although some people get carried away with that approach). One thing I would suggest eat wisely and well, to keep your immune system strong.

Editor’s note: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at drcmclean@penmed.com.