The only way I suspect transmission was someone spitefully exposing my toothbrush to fecal matter. Would it even be possible to transmit this way? If so, it would have been too small to detect visually or by taste. This Jstor article about experimentally infected tomatoes (pictures attached) seems to say not likely, based on "when contaminated samples were allowed to dry naturally, some cysts survived for 1 hr, but none survived after 2 hr." The toothbrush was sitting there all day long before I used it, and was definitely dry.
However, here is another article which seems to imply that less smooth surfaces, such as lettuce (or toothbrushes) may have a higher likelihood? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4788893/
"lettuce had the highest prevalence of contamination, and this may be ascribed to it is leaves which are capable of harboring parasites in-between and in addition to its uneven surfaces on which parasites are attached more easily than other vegetables with smooth surfaces"
I didn't see any fecal matter on the toothbrush, so if it had been transmitted that way, it would have been too small to detect.
Anyway, some symptoms still remain after treatment.
Treatment was standard Paromomycin/Tindamax, and multiple test results came back negative after treatment. I still have occasional diarrhea, and heart palpitations. A rheumatologist found a link between a vitamin D deficiency, and an immune response.
Basically, taking Vitamin D daily stops the heart palpitations. Also, a daily probiotic stops the diarrhea.
If this amoeba still does exist in small amounts, are there alternative therapies to try? Here is an article, for example, suggesting resveratrol: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4701480/
I also read somewhere else about the potential of chalcone-containing plants.