Saturday, November 17, 2012

Oh those Bartonella!

Bartonella Quintana (from here)

My friend across the pond put me onto a post describing Trench Fever that was a scourge of Allied troops in World War I. This is a topic that certainly has six degrees of interest surrounding it like the expanding ripples in a pond. (it is also something that would take forever to research without the Internet.)

As my friend and the article point out, there are three different lice (louse) infestations of man. There is head lice (the scourge of elementary school), with their little egg shells called nits (as in "nit picking"), pubic lice, ye olde crabs, and body lice which are the vector of Trench Fever. Apparently it wasn't appreciated until after WWI that the louse was the vector. There may have been a million cases of Trench Fever during the War which didn't lead to fatalities but did lead to incapacitation and, eventually, depression.

So, Ripple 1. Depression after combat. Two books that deal with the mental state of soldiers: first is actually a series, The Ghost Road, by Pat Barker. The focus is on shell shock but with the incidence of Trench Fever so high (it is rarely fatal) one wonders how many of the soldiers experiencing shell shock had comorbid depression sequelae to this infection. As a Rickettsia infection it is similar to Rocky Mountain spotted fever and, see below, Cat Scratch Fever. RMSF can have major CNS effects, but its main pathological effect is on blood vessels leading to necrosis of fingers and toes. Presumably this is due to invasion of the blood vessel wall by the organism. The second book that comes to mind is Birdsong by Sebastian Faulks. (I only now find out that it is also a part of a triolgy including The Girl at the Lion d'Or and Charlotte Gray; the first I have read but not the second). Neither Ghost Road or Birdsong explicitly mentions Trench Fever, to my knowledge though there is a sequence in Ghost Road where the soldiers get to take showers and laundry their clothes.

Ripple 2: Bartonella Quintana, transmitted by the louse and the causative organism of Trench Fever, has very interesting biology. How the biology relates to the symptoms it is hard to tell. For one thing the organism inhibits apoptosis of infected cells. Apoptosis, or programmed cell death, is a Holy Grail of cancer research. That is, most cells in the human that can be transformed into cancer cells are cells that reproduce. Bone marrow and the linings of the intestine and the lung are constantly turning over. Cells, maybe stem cells, are also constantly dividing to produce new bone marrow and epithelial cells. In turn, the old, senescent cells must commit hari kari, or apoptosis. This may have something to do with telomeres, repetitive nucleotide sequences that protects the ends of chromosomes. In any case, a cancer cell has apoptosis blocked in a similar manner to a cell infected with Bartonella Quintana. In the latter case, all that happens is that the disease persists and the patient can experience multiple relapses of Trench Fever. Not a very nice prospect but not as serious as cancer.

Ripple 3: Bartonella Hensalae and Quintana again. Bartonella Hensalae is a not uncommon infection best known as Cat Scratch Fever. Cats carry this bacteria but do not become infected. Actually, it is usually kittens less than six months and they are prone to scratch! (I can't really tell you from personal experience because I am not very friendly with cats.) After the scratch, which sometimes becomes locally infected, the bacteria goes to a regional lymph node and can cause gross and painful enlargement. This scares the living devil out of everyone since mimics lymphoma. There is also a meningitis caused by Bartonella Hensalae but is is uncommon.

One further biologic property of B.Hensalae is that it induces angioneogenesis, that is, the growth of new blood vessals. This also occurs with B. Quintana. Ironically, this is also a property of cancer cells. Without angioneogenesis, there would be no growth of tumors since they would run out of their blood supply. Much research is going into this field, led in the past by Judah Folkman (very interesting man, he.) In the case of these two bacteria, it is termed Bacillary Angiomatosis.

I think one could follow the ripples out pretty far. Interestingly, scratching around the Internet looking up these links raises a lot more questions than it answers. While similar in many respects, infections with the three organisms B. Quintana, B. Hensalae and Rickettsia rickettsii are vastly different, even though they each have similar biology (untreated R. rickettsii can easily be fatal). On the other hand, why is it that the simple little head louse while causing infinite consternation in the classroom is basically harmless?

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