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Melissa
Kaplan's |
A Tick By Any Other Name...
...can still carry Borrelia and other infective organisms
©2004 Melissa Kaplan
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Despite the fact that the CDC and various public health agencies are proved wrong time and again when it comes to Lyme disease (borreliosis) and other tick-borne infections, tick species pretty much ignore geographic boundaries. More to the point, the organisms that live happily in ticks as part of their lifecycle don't much care if they are living in a tick or in another suitable host, just so long as they can live, feed and breed long enough to get their genes out into the future. Adaptable little beasts that they are, they, too, break the rules, refusing to stay within the boundaries insisted upon by too many researchers and physicians. While many tiny and microscopic arthropod species have definite preferences for the host species on or in which they live, many are able and willing to inhabit more than one species. These more opportunistic organisms thus have a better chance of surviving as a species if their preferred host species should be eliminated from that particular habitat. And so we have "deer ticks" that migrate to and thrive on the blood of mammalian species other than the particular species or subspecies of deer found in any one area. Mice, housecats, dogs, humans - any warm-blooded mammal appears to be a suitable target for a heat-seeking tick driven by his inner parasite. And that explains how people who swear they have never, ever, ever gone hiking or come within shooting distance of a deer can get Lyme disease, or other common tickborne infections (TBI), including Bartonella (cat scratch fever which, contrary to that common name, doesn't just come through scratches from a cat), Ehrlichia, Babesia, and Tick-borne Relapsing Fever, to name a few. To make things a little more interesting, individual members of a species can develop traits that make them different from other members of their species. Sometimes the differences are so great that the changed group can no longer mate successfuly with the unchanged group. Called species, these organisms tend to come about when one group of individuals becomes isolated from other members of its species. This could happen when a new river or a highway, for example, cuts a species territory in two. Or, when islands of forest or grasslands are left isolated when a housing or commercial development is built on previously undeveloped land or land that has long lain fallow. Sometimes, a single species may undergo minor changes. The changes may be enough to discerne with close inspection, but they may still be able to successfully reproduce with one another. These changed individuals, if their change is noticed by scientists, are called subspecies, when the animal in question is larger than a microbe; strain and serotype are used when talking about subspecies of microbes. While subspecies may still be able to mate with other subspecies of the same species, or with full species members, they may be different enough from the full species and other subspecies to elude being detected or properly identified in tests or other population sampling. The real problem arises when species and subspecies are evolving, but science has no clue that they yet exist. Or, science may know that they exist and can identified and name them, not science may not know enough about them to understand how a particular subspecies may respond to the treatments used on the nominate species...or not. Huh? For example, the species of Borrelia commonly found in Europe are different than the species found in Russia, which are different than the Borrelia found in the U.S. Here is a sampling of the presently known 32 species of Borrelia:
* B. miyamoto-like spirochaetes have been detected in Ixodes ricinus in Sweden and I. scapularis in the USA. That's was straight forward enough. Now, to complicate things a bit: In the U.S., thus far, we have the following identified species, each of which may each have one or more strains, either known and as yet unknown. In addition, it is possible that a single nymph or adult tick (or flea, or louse) be carrying more than one species of Borrelia, one or both of which may be passed into whatever animal the arthropod feeds upon.
The regional differences in subspecies may affect more than their appearance and biology: the differences may also affect how successfully they are detected in tests designed to identify, say, the Borrelia species endemic to Connecticut, making it not very effective in finding the California Borrelia. This difference may also affect how susceptible which species or subspecies are to specific antibiotic/antimicrobial protocols, which may help explain why not everyone responds the same way to the same treatment protocols. And, just to make things a wee bit more complicated, especially when it comes to testing and treatment:
and, to show that strains can truly be global: Characterization
of Borrelia burgdorferi strains isolated from Ixodes pacificus
ticks in California. In a survey of 1,714
adult Ixodes pacificus ticks collected in northern California, 24 (1.4%)
were found to be infected with spirochetes that reacted with an anti-Borrelia
burgdorferi polyvalent conjugate in direct immunofluorescence tests.
Eleven isolates of B. burgdorferi from these ticks were characterized
by monoclonal antibody, polyacrylamide gel electrophoresis, and Western
blot (immunoblot) analyses. Ten of the isolates had molecular and antigenic
characteristics similar to those of other U.S. isolates. One strain, cloned
by limiting-dilution techniques, was different from any previously reported
U.S. strain, but similar to reported European strains. The cloned strain,
DN127-Cl9-2, did not react with monoclonal antibodies to Osp A and Osp
B major proteins found in most of the U.S. strains. It exhibited an abundant
protein with an apparent molecular weight of 25,000. J Clin Microbiol.
1987 December; 25 (12): 2296–2301 Full
text of article...
Sources Tick-borne Relapsing Fever Caused by Borrelia hermsii, Montana (CDC) Borrelia lonestari DNA in Adult Amblyomma americanum Ticks, Alabama (CDC) Borrelia Classification (Kenyon) The Spirochaete: Borrelia Strains (EUCLAB) Eubacteria (speciesaccounts.org)
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http://www.anapsid.org/lyme/tickids.html
© 1994-2014 Melissa Kaplan or as otherwise noted by other authors of articles on this site
