What is the difference between thick and thin blood smears in the workup of malaria?

Updated: Apr 26, 2019
  • Author: Thomas E Herchline, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Three thick and thin smears 12-24 hours apart should be obtained. The highest yield of peripheral parasites occurs during or soon after a fever spike; however, smears should not be delayed while awaiting fever spikes.

Thick smears are 20 times more sensitive than thin smears, but speciation may be more difficult. The parasitemia can be calculated based on the number of infected RBCs. This is a quantitative test.

Thin smears

Thin smears are less sensitive than thick smears, but they allow identification of the different species. This should be considered a qualitative test.


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