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Category: Clinical Microbiology
Detection of Blood Parasites, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818814/9781555818814_Chap9.8-1.gif /docserver/preview/fulltext/10.1128/9781555818814/9781555818814_Chap9.8-2.gifAbstract:
During some stages in their life cycle, Plasmodium spp. (malaria), Babesia spp., Trypanosoma spp., Leishmania donovani, and the filariae are detectable in human blood ( 1 , ref9.8.1_2 , ref9.8.1_3 , ref9.8.1_4 – 5 ). Plasmodium and Babesia species are found within the RBCs; trypanosomes and microfilariae, the larval stage of filariae, are found outside the RBCs; and Leishmania amastigotes are occasionally found within monocytes. Trypanosomes and microfilariae, which frequently are present in low numbers, exhibit motility in freshly collected blood films, and this can aid in their detection. However, species identifications of all blood parasites are usually made from either or both of two types of stained blood films: a thin film and a thick film. These films can be made from whole or anticoagulated blood or from the sediment of a variety of procedures designed to concentrate trypanosomes and microfilariae in the blood. Although the films have traditionally been stained with Giemsa stain, many infections are detected and diagnosed by using Wright’s stain or other blood stains, including the rapid stains. Delafield’s hematoxylin is used to enhance the morphological features of microfilariae.
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Method of thick-thin combination blood film preparation. (a) Position of drop of EDTA blood; (b) position of applicator stick in contact with blood and glass slide; (c) rotation of applicator stick; (d) completed thick-thin combination blood film prior to staining. (Illustration by Sharon Belkin; from reference 2 .)
BinaxNOW malaria device for result interpretation. Courtesy of Alere (http://www.alere.com/us/en/product-details/binaxnow-malaria.html).
Advantages of thick and thin blood films
Potential problems using EDTA anticoagulant for the preparation of thin and thick blood films
Parasitemia determined from conventional light microscopy: clinical correlation a
Malaria resistance a
Advantages and disadvantages of buffy coat films