Early acquisition of herpes simplex virus type 1 antibodies in children--a longitudinal serological study.

BACKGROUND: Herpes simplex virus type 1 (HSV-1) infections are commonly acquired in childhood, asymptomatically or as a symptomatic infection. However, little is known about the time of HSV seroconversion during infancy and early childhood. OBJECTIVE: To investigate the acquisition of IgG-antibodies to HSV in infants and children. STUDY DESIGN: A longitudinal study, using type-specific HSV-1 and herpes simplex virus type 2 (HSV-2) enzyme-linked immunosorbent assays on sera collected from the mother and from their child at the age of 3, 5, 6, 12, 13 and 30 months. RESULTS: The maternal seroprevalences for HSV-1 was 65% and for HSV-2 19%. A gradual loss of maternal antibodies was seen, with few infants having detectable HSV-1 antibodies at the age of 1 year. A more rapid decline was registered for HSV-2 antibodies. A small number of new HSV-1 infections occurred in 3-5-month olds and more than half of the new infections were detected before the age of 13 months. At the age of 30 months, 30% of the children were HSV-1 antibody positive. CONCLUSION: Seroconversion to HSV-1 commonly occurs already during infancy, suggesting that HSV-1 is transmitted primarily from parent to child.