Diagnostic Value of Neutrophil CD64 in Differentiating Scrub Typhus From Febrile Diseases.

BACKGROUND

Scrub typhus, lacks specific early symptoms, and traditional serological tests have low sensitivity. This study shows that CD64 has superior diagnostic performance compared to CRP and PCT in bacterial infections.

METHODS

This retrospective study analyzed 242 febrile patients admitted to the Jiangsu Province (Suqian) Hospital (January 2023-December 2024), categorized into non-specific fever (n = 186) and scrub typhus (n = 56). The CD64 expression was quantified via flow cytometry (BD FACS Canto II) within 48 h of admission. ROC analysis evaluated diagnostic performance using AUC, sensitivity, specificity, and Youden index. Mann-Whitney U and Chi-square tests compared groups (SPSS v26.0), with significance at p < 0.05.

RESULTS

The scrub typhus group had significantly higher CD64 levels (median: 2.90 [IQR: 1.00-5.20]) than non-specific fever (0.23 [0.10-0.58], p < 0.001). ROC analysis demonstrated CD64's high discriminatory power: AUC = 0.938 (95% CI: 0.882-0.995) for scrub typhus vs. non-specific fever (sensitivity = 91.7%, specificity = 89.8%). Traditional markers like WBC and lymphocyte percentage showed high discrimination against non-specific fever (AUC = 0.973-0.989).

CONCLUSION

This study shows that CD64 is an efficient biomarker for differentiating scrub typhus from febrile diseases, offering crucial evidence for establishing rapid diagnostic pathways and holding value for early triage of febrile patients.