When costs were recalculated in hypothetical scenarios to see if excluding dengue upfront will be cost saving for NDF patients, if the cost of RT-PCR is USD 22.4, in all scenarios considered, (0%, 20% and 50% of Q2 and Q3 patients returning for an IgM test) the total cost per patient was still cheaper (USD 35.73–36.53) than the observed average cost per stay for NDF patients (USD 47.36). This evidence concerns the gene CD40LG and dengue disease.