Turned up to eleven: Fair and Balanced

Monday, March 17, 2003


Killer Pneumonia
Well, this has certainly been a big story, and there is justifiable concern in the health professional and CDC circles (follow that link to find out the latest info on the hunt for the etiological agent, err, I mean the bug that causes this disease). Since I am not a senior epidemiologist or "Hot Zone" type virus hunter, I feel comfortable engaging in some wild speculation.

It's probably a virus

That is my educated guess. The lung is a pretty easy place to investigate for bacterial infections (TB screening uses X-ray's, for example), so it is pretty unlikely that a bacterial pneumonia would be unidentified for this long. Bacteria are also big (on microbiological scales) and visible by easy, specific staining techniques, so they can be seen in a common light microscope. Virus particles, on the other hand, can only be seen under an electron microscope, making the search for them much more difficult. It is possible, although I am not familiar with it, that the agent of the disease is not actually living in the lung. I would need to consult with an MD on that one. My understanding, though, is that pneumonia is a colonization disease, that is, the function of the lung is disrupted by locally present microbes, whose actions cause the lungs to fill with fluid. I am sure that this could be wrong.

(sound of new window opening, google search progressing...)

It is probably a (wierd) bacterium

This medical school lecture note page by Dr. Neal Chamberlain seems to me to give a nice overview of the many and varied etiological agents that cause pneumonia. I was right about the proximate nature of the cause, but I should amend the above to include the distinct possibility of mycoplasma, chlamydia, and rickettsiae as elusive causes of pneumonia. The "typical pneumonia" that Dr. Chamberlain discusses is unlikely to be the current mystery disease, because we would know it by now (they are easy to identify). If I had to pick an odds on favorite from the potential bacterial agents, I would go with Mycoplasma, which is a very interesting bacterial genus, from an evolutionary standpoint. It is an obligate intracellular organism, which means it can't live outside a cell, but it is a bacterium, in that it has the genetic markers of that "urkingdom" of life. It is, in essence, a product of degenerative evolution, in that it has lost a huge number of genes from its common ancestor with other bacteria, and now lives on a "bare minimum" genome. This makes it a very fragile microbe, in one sense, but it is exquisitely capable of living inside eukaryotic cells. Because it has lost most of the trappings of bacterial life, it is also very much less susceptible to antibiotic treatment. In a number of ways, this microbe fits the description, as can be seen in the table on "atypical pneumonia" in the good doctor's lecture. The only difference I can see between Mycoplasma pneumonia and the current mystery malady is its incubation period (the mystery illness is quicker), and perhaps its severity. Both of these characteristics are potentially things that could have arisen by mutations in the microbe.

If I am right about this (certainly a longshot), it is good news, because Mycoplasma is a known quantity. It can be detected in cell culture, and it should be susceptible to some antibiotics. Mycoplasma is a common contaminant of cell culture, so there is a fair amount of info known. Plus, its very small genome has been sequenced and annotated, so combatting a new strain should be tractable. Considering the alternative (some crazy new virus that can't be stopped), I would say Mycoplasma sounds pretty good to me.

Also, just to put people's minds at (some) ease, I have never heard Mycoplasma mentioned as a potential bioweapon, so I seriously doubt that there is any bioterror story here. Of course, Mother Nature has shown herself plenty capable of dealing humanity a pretty substantial blow without any help, thank you very much. I sincerely hope that the good people at CDC, who I have tremendous faith in, figure this one out soon.

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