Herpes Simplex Virus Infection in Infants

Background: National neonatal surveillance for herpes simplex virus (HSV) disease suggests that the incidence of HSV disease may be higher in Queensland (QLD) than in other Australian States. We sought to investigate the incidence via a retrospective 13-year evaluation of statewide laboratory data, autopsy data and linked clinical records of infants with laboratory confirmed infection. Methods: All positive polymerase chain reaction HSV 1 and 2 results were obtained for infants 0-3 months of age from January 1, 2005 to December 31, 2017. Clinical data were obtained from patient records and parent questionnaires were used to evaluate long-term sequelae. Results: One hundred seventy-two infants with HSV positive polymerase chain reaction results: 121 (70.3%) with HSV 1. Of 104 (60.5%) infants with signs of HSV disease, 76 (73.1%) were neonates (≤28 days of age) [incidence 9.6 (95% confidence interval, 7.0-11.5) per 100,000 live births] and 28 (26.9%) were young infants (29-90 days of age) [3.6 (95% confidence interval, 2.4-5.4) per 100,000 live births]. The annual incidence of neonatal HSV disease increased significantly in Queensland over the study period (P < 0.01). Of the 76 neonates with HSV disease, 58 (76.3%) presented with the skin, eye, mouth (SEM) disease, 17 (22.4%) with HSV encephalitis and 11 (14.5%) had disseminated disease. Young infants presented with HSV skin, eye, mouth disease (21, 75.0%) or HSV encephalitis (6, 21.4%). Death occurred in 12/104 (11.5%) infants (all neonates) with 10 attributable to HSV disease. Conclusion: The incidence of neonatal HSV disease in QLD is almost 3 times the national reported incidence. Further research is being undertaken to explore reasons for this change and implications for practice.