Which species of Plasmodium is relapsing?

Plasmodium vivax is recognized as a species of Plasmodium that causes relapsing malaria. The characteristic feature of relapsing malaria is the ability of this species to remain dormant in the liver, leading to potential recurrence of the disease after the initial episode has resolved. This dormant stage is due to the formation of hypnozoites in the liver, which can reactivate later, causing a relapse in the infection.

In contrast, while other species can cause malaria, they do not exhibit this unique relapse phenomenon. For instance, Plasmodium falciparum is the most severe form of malaria and typically does not have a dormant stage. Plasmodium malariae can cause chronic infections but does not relapse in the same way as P. vivax. Likewise, Plasmodium ovale also is capable of relapsing malaria, but P. vivax is more commonly associated with this trait. Thus, Plasmodium vivax is the best answer to represent a relapsing species among those listed.