We used the case definition criteria of the Italian National Plan for Prevention, Surveillance and Response to Arboviruses (2020–2025) [6]: a probable case is defined as an individual exhibiting symptoms consistent with dengue (fever > 39 °C, nausea or vomiting, rash, aches and pains, retro-ocular pain) with a positive serology for IgM antibodies. The gene discussed is CD40LG; the disease is dengue disease.