Case report: An unusual late relapse of Plasmodium vivax malaria.

We observed an unusual case of Plasmodium vivax malaria who presented with an initial relapse four years after the primary infection. This occurred in Cameroon, where the patient, a 56-year-old priest, acquired a mild form of malaria and was treated with only chloroquine. Since he returned to Italy, he had not experienced any malaria-like symptoms, had not visited any other areas endemic for malaria, and had not received a blood transfusion. Blood smear microscopy confirmed the presence of Plasmodium spp. parasites, but unclear morphologic characteristics did not allow discrimination between P. vivax and P. ovale. A nested polymerase chain reaction-based molecular analysis identified P. vivax as the plasmodial species responsible. This case emphasizes the importance of taking into account the possibility of a very late initial relapse of P. vivax malaria and the relevant issues in terms of infection control.