As is well known, long-term malarial recurrences are a feature of human infections caused by species of Plasmodium. The frequency of recurrence varies. In P. falciparum malaria, long-term recurrence is rare, but not (contrary to popular belief) non-existent. P. malariae [Pm] and P. vivax [Pv] only will be considered below; and with reference to only the bone marrow as a site of parasite occurrence.
It has been known from individual cases of malaria that both Pm and Pv can be present in the bone marrow. Experimental work has in the meantime shown that Pv is, in fact, highly prevalent in bone marrow [see the first reference below]. Both species are "famous" for causing long-term malarial recurrences. As regards homologous long-term recurrences, it has generally been thought in the past that the origin is circulating blood-stage parasites of Pm; but hypnozoites of Pv. The former assumption has been based partly on minimal evidence that hypnozoites apparently do not occur in the life cycle of Pm. This aside, Pm infections are as persistent after blood-stage parasite inoculation as they are following sporozoite-transmitted Pm malaria. Even if hypnozoites do occur in the life cycle of Pm, long-term Pm recurrences in blood-stage-initiated malaria cannot be hypnozoite-mediated. It is biologically impossible, because hypnozoites are directly sporozoite-derived; and there are no sporozoites in post-passage, blood-stage Pm inocula.
TWO QUESTIONS are (this might not be immediately comprehensible, i.e. upon first reading):
(A) Given that the same non-hypnozoite parasite forms which occur in blood-stage-initiated Pv malaria are likely to occur in sporozoite-transmitted Pv malaria as well, can at least some LONG-TERM HOMOLOGOUS Pv malarial recurrences in sporozoite-initiated Pv infections have a NON-HYPNOZOITE parasite origin analogous to the non-hypnozoite parasite origin of long-term recurrences in blood-stage-induced Pm malaria?
(B) Can a non-circulating parasite source of recurrences be bone marrow (for example) in both the Pm and Pv hypnozoite-independent recurrence scenarios outlined here?
See the 2nd to 5th references below for combined elucidatory Pm extrapolative discussion in relation to Pv malarial recurrences.
"Plasmodium asexual growth and sexual development in the haematopoietic niche of the host" https://doi.org/10.1038/s41579-019-0306-2
"Malaria eradication and the hidden parasite reservoir" https://doi.org/10.1016/j.pt.2017.03.002
"Biological concepts in recurrent Plasmodium vivax malaria" https://doi.org/10.1017/S003118201800032X
"Do hypnozoites cause relapse in malaria?" https://doi.org/10.1016/j.pt.2015.02.003
"Dormancy in mammalian malaria" https://doi.org/10.1016/j.pt.2011.10.005