Hello,

We are a group of veterinarians looking into repeatable findings of unusual structures found in a group of animals with similar unusual complaints of unexplained hematuria, tender subcutaneous nodules, and easy fatiguability. We have repeatably found tiny fibers and tube or shell-shaped calcified structures in tissue samples from these animals. So far, we have been unable to definitively characterize the species that may be producing these objects, but light and electron microscopic studies have led us to consider a novel polychaete or mollusk, or even possibly something really unusual such as an organized myxozoan. One of the most obvious and unusual features of these organisms is that they contain fibers (possibly chaetae?) that can evert plume/fan-like structures from their tips, and sometimes from portions along their lengths. These fibers are quite small- generally only 5-10 microns wide, and potentially 200-400 microns long. Despite their small size, they repeatably contain a very intricate and complex system of pulleys, levers, ratchets, etc.. that we presume are present to evert the fan-like structures- which may be used for respiration/feeding? The fibers are highly refractive, and seem to contain tiny crystalline "gears". Portions of the fibers will stain with crystal violet and/or Safranin O, but in general, the fibers stain poorly with the standard H&E type histology stains. In addition to the fibers, there are often structures seen which resemble trophozoite stages of polychaete or mollusk-like organisms. (photos available in data files related to this project).

Is anyone familiar with organisms that have these features? We would be very grateful for any thoughts about what organism these fibers may be coming from, and/or links to any reference papers or atlas etc... that describes these structures and might help us focus our search for an identify of this possible novel parasitic organism. While we began our search in the veterinary patient population, we have evidence suggesting that this putative organism may be a zoonotic agent to immunosuppressed human patients. So, we are very eager to learn more about the candidate organisms that could produce such fibers, and relay those suggestions to the physicians of human patients who may be hosts of this possible novel pathogen.

Thanks you for your time and expertise!