Hematology thin smears perform equally to parasitology thick and thin blood smears for the diagnosis of Plasmodium and Babesia infections in a low prevalence setting.

Malaria and babesiosis are significant parasitic infections, requiring timely diagnosis to avoid severe complications. This study retrospectively compared hematology thin smears (HS) with parasitology thick and thin blood smears (PS), the gold standard for diagnosis, to evaluate HS's performance in detecting Plasmodium and Babesia infections. Of 529 cases with paired HS and PS testing, HS demonstrated 93.3% sensitivity and 99.8% specificity, with 97.7% positive and 99.4% negative predictive values. When only considering new diagnoses, HS and PS were 100% concordant. No significant difference was found in percent parasitemia between HS and PS, highlighting HS as a reliable diagnostic tool in settings where PS or other diagnostic modalities may not be readily available.IMPORTANCEThis study demonstrates that hematology thin smears-often available in laboratories that may not have other means of diagnosing blood parasite infections such as parasitology thick and thin smears, rapid diagnostics tests, or polymerase chain reaction-are an accurate and reliable way to diagnose Plasmodium and Babesia infections in a low prevalence setting.