ﬁt well with our ﬁnding of postnatal HSV CNS infection if allowance is made for exclusion of neonates. HSE classically presents as an acute illness characterised by fever and encephalopathy together with behavioural dis- turbances and/or motor deﬁcits and/or convulsions. No sign is pathognomic, but it is noteworthy that in our children <3 years old, convulsions (generalised or focal) were present in every case. Similarly, two studies of postnatal HSE2 7 report a predominance of convulsions in children aged <3 years as compared to older children who show a wider range of presentations. Neuroradiology of postnatal HSE typically reveals focal haemorrhagic lesions localised to the medial temporal lobes, the insula and the orbital region of the frontal lobes of the brain. However, in our series the parietal lobes were frequently affected, conﬁrming previous ﬁndings that in young children extra-temporal regions of the brain are often involved.2 3 8 HSE outcome is difﬁcult to predict early on and particularly in very young children in whom subtle defects may appear later; it is therefore important that almost all of our cases were followed up at least a year after presentation. Long-term sequelae were reported in many of the children. Adverse out- come was age-related and CT reﬂected this as abnormalities were described in all the younger children but in none aged >11 months. Likewise, high numbers of red cells in the CSF, reﬂecting haemorrhagic necrosis in the CNS, were conﬁned to the younger age group. Of other recent studies of the long-term outcome of HSV CNS infection, that is, at least 6 months after onset,2 9 10 one10 reported that patients 3–35 months old were more likely to be severely disabled than older children. Our series further suggests that those <1 year old were at highest risk. Poor neurological outcome is associated with delayed ini- tiation of aciclovir therapy and/or shorter courses of the drug but, although all children received aciclovir, the confound- ing effects of inadequate treatment could not be addressed as this information was not collected by us nor in the study of Ito et al.10 The inﬂuence of age of onset in relation to severity of long-term outcome requires prospective study taking into account the role of inadequate aciclovir therapy. In conclusion, this survey documents the incidence of HSV-induced serious neurological disease in young children in Britain and emphasises that there are various presenta- tions ranging from frank encephalitis to severe illness with Short report fever and convulsions, and even a milder form lacking lengthy encephalopathy. Disease was commoner in children aged 2–11 months than in older children, and neurological seque- lae and consequent severe disabilities showed the same trend. HSV CNS infection must always be considered in children presenting with convulsions even when apyrexial, without encephalopathy and with normal CT ﬁndings. Acknowledgements The authors thank the British Paediatric Surveillance Unit, supported by the Department of Health, for facilitating the data collection and the reporting clinicians, particularly those who completed the questionnaires. Any views expressed (in publications) are those of the investigator and not necessarily those of the BPSU or DH. The authors are also grateful to the microbiologists and virologists who took the time and trouble to send specimens in support of the survey. Funding The authors thank the Wellcome Trust for funding (project grant 051350/Z to KNW). Analysis of HSV CNS infection was made possible by funds from the Encephalitis Society’s 10th Anniversary Research Prize to KNW. KNW was supported in part by funding from University College London/University College London Hospitals Comprehensive Biomedical Research Centre. Competing interests None. Ethics approval This study was conducted with the approval of the Public Health Laboratory Service Ethics Committee, London, UK. Provenance and peer review Not commissioned; externally peer reviewed. REFERENCES 1. Ward KN, Andrews NJ, Verity CM, et al. Human herpesviruses-6 and -7 each cause signiﬁcant neurological morbidity in Britain and Ireland. Arch Dis Child 2005;90:619–23. 2. Elbers JM, Bitnun A, Richardson SE, et al. A 12-year prospective study of childhood herpes simplex encephalitis: is there a broader spectrum of disease? Pediatrics 2007;119:e399–407. 3. De Tiège X, Rozenberg F, Héron B. The spectrum of herpes simplex encephalitis in children. 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