Relapsing Plasmodium vivax malaria with atypical parasite forms and phagocytosis by peripheral neutrophils

A case of atypical Plasmodium vivax malaria is presented. The clinical follow-up has allowed to characterize three consecutive malaria clinical episodes within one year. At the first attack, 39% of the infected red blood cells were parasitized by gametocytes. Furthermore, rare crisis forms, exceptional "pseudoparthenogenesis" forms, a few equatorial trophozoites, malaria pigment-containing leucocytes and phagocytized parasites were also found in the thin blood smears. At the second malaria episode, morphological aspects were quite similar, but the gametocyte percentage decreased and that of the equatorial trophozoite forms increased. Only at the third attack, was the morphology typical of P. vivax. The Plasmodium species and the absence of mixed infection were unequivocally confirmed using polymerase chain reaction. Atypical strains of P. vivax are relatively frequent. Nevertheless, to our knowledge, neither so high a gametocyte percentage, nor extensive P. vivax peripheral phagocytosis were previously reported.