Lysenko et al.’s hypothetical P. vivax tachysporozoites  multiply in the liver soon after inoculation into the host, whereas their hypothetical bradysporozoites form hypnozoites , which are the origin of relapses. This "tachy" and "brady" terminology is an extension of usage unrelated to malaria .
For a homologous P. vivax malarial recurrence to be a relapse means that firstly, a tachysporozoite(s) will have had to initiate what became a patent infection. But it also means that a sister sporozoite(s) with basically the same genotype must have been, simultaneously, a bradysporozoite(s). This is how hypnozoite-derived recurrent parasites in the bloodstream could in theory come to be genotypically similar to those from an earlier time point .
However, do different sporozoites having the same genotype in fact act inconsistently by functioning as either tachysporozoites or bradysporozoites ? Perhaps they do.
If not, then numerous (more than meets the eye) non-reinfection homologous recurrences of P. vivax malaria will obviously be recrudescences (clonal merozoite origin), not relapses .
Future research involving plasmodial sporozoites  will hopefully contribute to providing the answer to the question posed in the title of this blog.
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2. Markus MB. Terms for coccidian merozoites. Ann. Trop. Med. Parasitol. 1987;81(4):463. https://doi.org/10.1080/00034983.1987.11812147
3. Markus MB. Source of homologous parasites in recurrent Plasmodium vivax malaria. J. Infect. Dis. 2012;206(4):622–623. https://doi.org/10.1093/infdis/jis393
4. Markus MB. Biological concepts in recurrent Plasmodium vivax malaria. Parasitology. 2018;145(13):1765–1771. https://doi.org/10.1017/S003118201800032X
5. Ruberto AA et al. Single-cell RNA sequencing of Plasmodium vivax sporozoites reveals stage- and species-specific transcriptomic signatures. bioRxiv Preprint. 2021 (posted 24 November). https://doi.org/10.1101/2021.11.24.469176