Early recognition of dengue illness in neonates due to perinatal transmission deserves special attention as it can be missed [1]. Onset of fever in the newborn varies from 1 to 11 days after birth with an average of 4 days and lasts 1-5 days. Falsely-negative dengue serology on first two days of life may be due to low viremia at that time [2]. The duration of viremia and febrile phase lasts longer in newborns experiencing primary infection due to more gradual antibody or cellular response.

We recently managed two neonates who were asymptomatic at birth but after one week, they developed signs and symptoms of severe dengue infection; one of them developed severe thrombocytopenia and encephalopathy. Both these neonates were negative for dengue infection by routine screening at birth and were missed. Hence, screening for NS1 antigen at birth in newborns of mothers with dengue illness may not be sufficient. Non-structural antigen (NS1) can become positive even up to 7 days after birth peaking at the 5th day [3]. IgM and IgG antibodies can take 2-3 weeks to be positive. Dengue virus illness hence, can be easily missed in the early newborn period if we do not follow-up closely.