An unusual adhesion between red-cells and platelets in falciparum malaria

A Thai female patient infected with P. falciparum had 80 per cent P. falciparum infected red cells at ring stage in the peripheral blood smear. The complications included anemia, thrombocytopenia, acute renal failure and pulmonary edema. A marked decrease in platelets number, low hemoglobin, low hematocrit and decreased red blood cell count were detected. More than 70 per cent of total platelets detected in the blood smear were binding to parasitized red blood cells. The number of binding platelets declined with decreasing per cent parasitized red cells. It was also noted that some platelets (10-20%) adhered to nonparasitized red cells. An increased number of large lymphocytes was shown by increased numbers of large unstained cells (LUC) by H* 1 automated analyzer. The peripheral blood smear showed abnormal binding of platelets to the infected red cells more frequently than to non infected red cells and free platelets on the day of high parasitemia. This abnormal phenomena was related to the number of platelets in the circulation. When the parasitized red cells were not detected in the blood smear, the number of platelets in the circulation had returned to normal.