Dear Editor, we would like to share ideas on the publication “Clinical features of patients with Rocky Mountain spotted fever (RMSF), dengue and chikungunya infection¹.” Mora et al. concluded that “Rash on the palms and soles, edema and absence of pruritus, together with high levels of direct bilirubin and severe thrombocytopenia could be useful indicators to differentiate patients at RMSF advanced stages from those with dengue and chikungunya¹.” We agree that the finding might be useful in clinical practice. However, the diagnostic value of the proposed clinical characteristics has to be further verified. There are several tropical vectors borne disease and common clinical presentations might be seen. For example, a dengue case might present all mentioned clinical characteristics². In addition, concurrent infection is possible and the proposed clinical characteristic might not be useful for diagnosis. For example, coinfection between RMSF and dengue is possible and is difficult for diagnosis and can lead to fatality³.