A Rapid Concentration and Identification Technique for Human Malaria Infections Using a Mouse Model

Red blood cells infected with malaria parasites experience a change in density making them lighter (less dense). This paper reports a new, rapid diagnostic technique using this change in density in the infected red blood cell. It is not only easy to use, but it is also compatible with the technological conditions found where the malaria problem is most acute - in many developing countries of the world. A small sample of blood drawn from a simple finger stick can be concentrated and examined microscopically for malaria parasites within 10 minutes. The thick film slide preparation, presently used, takes a minimum of six hours just to dry. In this study a few drops of blood from the tail of Balb/c female mice infected with either Plasmodium chabaudi or Plasmodium berghei were drawn into a standard (75x1.2) heparinized capillary micro-hematocrit tube. The tube was sealed at the bottom and centrifuged for 5 minutes at 7,000 revolutions per minute in a hematocrit centrifuge. Packed cell volume is determined concentration point, the hematocrit tube is broken, and the blood cells expressed onto a clean glass side. The concentrated blood cells were then spread into a thin blood film, stained with Hemal stain and read microscopically. Comparison of the thin film with the concentrated thin film (CTF) readings showed that CTF concentrated malaria-infected erythrocytes an average of 6.5 times for P. chabaudi and 8.1 times for P. berghei. This concentration technique could be of value in the rapid diagnosis of human malarial infection. It reduced preparation time, slide reading time, and false negatives. This technique provides advantages over the currently used thick and thin film methods. The CTF technique was used to diagnose one person infected with human malaria, P. vivax. The CTF concentration was 12.5 time greater than the film method