We observed that more CD8+ T lymphocytes expressed Ki67 in dengue fever cases when compared to controls, either expressed in absolute numbers or percentage of stained cells (median 14 cells/μl, IQR, 7–40 vs. 4 cells/μl, IQR, 3–12, p = 0.002; median 4%, IQR, 2–14 vs. median 1%, IQR, 1–2, p<0.0001). The gene discussed is CD8A; the disease is dengue disease.