What are the findings of peripheral blood smears in babesiosis?

Updated: Apr 01, 2021
  • Author: Rachel E Strength, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Wright-stained or Giemsa-stained peripheral blood smears reveal intraerythrocytic ring forms with a central pallor. Stained smears from patients with Babesia infection, in addition to having these intraerythrocytic ring forms, may also demonstrate merozoites arranged in a tetrad configuration resembling a Maltese cross. Tetrad forms are pathognomonic of babesiosis. In individuals with asymptomatic infection, smear results may be negative.

Babesia species, tetrad formation. Image courtesy Babesia species, tetrad formation. Image courtesy of Centers for Disease Control and Prevention.

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