It has long perplexed me why Borrelia bacteria appear to be so abundant in the blood of other mammals but so sparse in human blood. An Ixodes tick, generally the poppy seed size nymph form has a blood meal, typically from a mouse, becoming infected with Lyme along with an assorted host of other co-infecting germs. Even though the tick takes many such meals - (how much blood can the tick eat)? - it would appear that spirochetes must exist in fairly high numbers in circulating blood in these other mammalian hosts.
In humans the paradigm/narrative states: the spirochetes stick to the extracellular matrix, become intracellular, convert to cyst forms, avoid immune defenses and antibiotics by avoiding blood and body fluids and finds safe harbor within biofilm communities.
"It is a tissue bacteria, not one to be found in the blood."
Now thinking about these statements they do seem wrong. Textbooks have instructed me the bacteria is spread via the blood stream. I conveniently discarded this explanation along other textbook things Lyme. But - Lyme bacteria cannot spread to many disparate tissues including the central nervous system unless carried by circulating blood. Of course I knew this. Right.
We have looked for the bacteria in blood of infected humans by PCR testing, a direct assay for detection of Lyme DNA. This is what has mislead me. The results have been almost always negative. Getting a positive PCR for Lyme has been like hitting the jackpot.
With improved culture techniques Lyme bacteria have now successfully been cultured from human blood consistently.
Culture is the absolute gold standard for proving the presence of the bacteria and chronic Lyme disease (not post Lyme syndrome).
Why the negative PCRs?. PCR technology uses primer pieces of DNA which target sub-regions of the organism's complete genome. These reactions are amplified and read by a machine. The primers target specific regions of DNA known to be conserved within different strains of the organism.
Sample size may be an issue. The PCR machine may be sampling a small amount of DNA taken from a small sample of blood. PCR testing may not be sensitive enough to detect the most minute traces of DNA. There are also various technical glitches which may occur with the technology.
With culture techniques a larger amount of blood/DNA may be tested. Perhaps this is why culturing has been more successful.
Bottom line: new staining and culturing techniques may be shattering another part of the paradigm. Lyme is not just a tissue pathogen in humans but can usually be found in blood if you just know how to look for it.