Of note, Hu et al. demonstrated that counts of CD4+ T-cells < 68 cells/mm3 combined with CD8+ T-cells < 111 cells/mm3 were independent risk factors for the development of IPA in SFTS patients, and Song et al. demonstrated that CD4+ T-cells < 300 cells/μL and CD8+ T-cells < 400 cells/μL were also independent risk factors for IPA. Here, CD4 is linked to Ito hypomelanosis.