Babesia microti infection, Giemsa stained thin smear.
|Intraerythrocytic protozoa measure 1-3 microns. The organisms resemble Plasmodium falciparum; however, Babesia parasites present two distinguishing features. They vary more in shape and in size and they do not produce pigment. The picture at left is a 67-year-old woman, status post-splenectomy, infection probably acquired in Long island (New York).|
|Infection with Babesia. Giemsa stained thin smears. Note the tetrad on the left side of image A, a dividing form pathognomonic for Babesia. Note also the variation in size and shape of the ring stage parasites (compare A and B), and the absence of pigment. A 6-year-old girl, status post splenectomy for hereditary spherocytosis, infection acquired in the U.S.|
Agarose gel (2%) analysis of a PCR diagnostic test for detection of Babesia microti DNA. PCR was performed using a nested protocol with primers BAB1 and BAB4 (first round) and BAB2 and BAB3 (second round).
* Lane S: Molecular base pair standard (50-bp ladder). Black arrows show the size of standard bands.
* Lane 1: First step amplification with primers BAB1 and BAB4 of the nested PCR protocol for detection of B. microti in DNA extracted from whole blood. The specimen, serologically positive for B. microti, was submitted to the CDC by the American Red Cross. The red arrow shows the single-step PCR diagnostic band for B. microti (size: 238 bp).
* Lane2: Nested PCR with primers BAB2 and BAB3 using as template the product of the first step amplification. The blue arrow shows the nested PCR diagnostic band for B. microti (size: 154 bp). Please note the enhanced sensitivity of B. microti DNA detection with the nested reaction.