Intralymphocytic schizonts associated with an initial infection of Saurocytozoon tupinambi in Tupinambis teguixin

Abstract

An initial natural infection of Saurocytozoon tupinambi in a juvenile Tupinambis teguixin from Venezuela was studied for 131 days following capture of the host. Intralymphocytic parasites appeared in this sequence: small uninucleate and binucleate stages (days 1–31 and again on day 41); schizonts with 3–102 nuclei (days 8–14 and 29–35); immature gametocytes (days 29–35) and apparently mature gametocytes of Saurocytozoon tupinambi from day 41. Maximum parasitemia of trophozoites and binucleate schizonts occurred on day 4 when 11% of lymphocytes were infected. Maximum parasitemia by larger schizonts occurred on day 8 at 0.13% of lymphocytes, while maximum gametocytemia was found on day 49 with 16.4% of lymphocytes parasitized. Two types of schizonts were observed: intralymphocytic and the same type free of host cells, and fragments of varying size which may have been torn from capillary endothelium. Due to presence of concurrent infection by a small Plasmodium species, identity of intralymphocytic asexual stages with S. tupinambi cannot be established. Presence of asexual and sexual stages in the same type of host cells (lymphocytes and close derivatives), sequential appearance of trophozoites, schizonts and gametocytes over a period of 40 days, and correlated fluctuations in lymphocyte density suggest they are conspecific, and that Saurocytozoon, which has a plasmodiid type of sporogony may prove to further differ from leucocytozoids by presence of an asexual cycle in circulating blood cells.