BackgroundNeonatal herpes simplex virus infection is a rare but dangerous condition with a high mortality and morbidity unless recognised and treated early. A recent study1 suggests that the UK incidence may have increased since the last national surveillance studies were undertaken 15 and 30 years ago.2,3 There is currently no national guidance on when to initiate treatment for suspected neonatal HSV. Rising numbers of HSV cases may support the wider use of empirical treatment.ObjectivesTo define the: (1) current burden of HSV disease and virus types, in UK and Irish infants less than 90 days, over a two-year period, (2) types of HSV disease ie disseminated, meningoencephalitis or skin/eye/mouth disease, (3) presentations and management, (4) source of transmission, (5) antenatal risk factors.MethodsProspective surveillance of HSV infection in infants < 90 days of age in UK and Ireland commenced in July 2019 through the British Paediatric Surveillance Unit (BPSU). Paediatricians reporting cases were requested to complete a detailed semi-anonymised questionnaire. Case notifications & data from completed questionnaires during the first 18 months, July 2019 - Jan 2021, are reported here.Results137 cases reported to BPSU: 8 were errors, 80 clinicians completed questionnaires, 21 confirmed duplicates, leaving 59 cases for analysis. Estimated incidence is 6.9 cases per 100 000 live births based on 2019 UK & Ireland birth rates. 31 (53%) male, 17 (29%) born <37 weeks. 21 (36%) had disseminated (blood pcr positive), 18 (30%) encephalitis and 20 (34%) skin/eye/mouth (SEM) disease. HSV1: 29 (49%), HSV 2: 25 (42%), unknown:5 (9%). More of those with disseminated and CNS disease had HSV2 infections and more with SEM disease had HSV1. Presenting features of disseminated disease were non specific and only 3/21 (14%) presented with a fever. 10/21 (47.6%) had a CRP of less than 20 at presentation, 11/21 (52.3%) had a transaminitis. Disseminated disease was present in 4/5 (80%) babies born at <28 weeks and 11/39 (28%) >37 weeks gestation.Aciclovir was commenced in 54/59 but in only 23/59 (39.0%) on the day of presentation. Overall mortality was 22% but 57% in those with disseminated disease. Mortality by gestation was 60% <28 weeks, 25% 28–36+6 weeks and 18% >37 weeks.ConclusionsIncidence of neontatal HSV has doubled since the last national surveillance study. Mortality remains high and presenting features of disseminated disease are non-specific. Absence of fever in 86% of cases demonstrates that HSV should not only be considered in the assessment of the febrile infant. Awareness of this disease needs to be raised to enable early recognition and treatment.ReferencesBatra D, Davies P, Manktelow BN, et al. The incidence and presentation of neonatal herpes in a single UK tertiary centre, 2006–2013. Archives of Disease in Childhood 2014;99:916–921.Tookey P, et al. Surveillance of neonatal herpes in the British Isles 2004–2006. Submitted for publication.Tookey P1, Peckham CS. Neonatal herpes simplex virus infection in the British Isles. Paediatr Perinat Epidemiol 1996 Oct;10(4):432–42.