44 Viral Central Nervous System Infections in Canadian Infants <90 Days Old: Encephalitis as a Predictor of Neurodevelopmental Morbidity

Herpes simplex virus (HSV) and enterovirus (EV) are important causes of central nervous system (CNS) infections in young infants. Though long-term morbidity has been linked to HSV, there is still limited data on outcomes of other viral CNS infections in young infants. 1) Conduct a descriptive analysis of viral CNS infections in infants <90 days old, 2) comparatively analyze outcomes of HSV and non-HSV CNS infections in neonates, and 3) determine predictors of neurodevelopmental morbidity and mortality following neonatal viral CNS infections. The Pediatric Investigators Collaborative Network on Infections in Canada’s database (January 2013-December 2014) was used to identify infants <90 days of age with proven viral CNS infection. Infants with seizures and/or abnormal head imaging suggesting parenchymal involvement were presumed to have encephalitis. There were 111 viral CNS infections comprising HSV (N=7; 6%), EV (N=103; 93%), and human parechovirus (N=1; 1%). Thirteen (12%) infants fulfilled criteria for encephalitis; 6 (86%) HSV and 7 (7%) EV. Infants with encephalitis were younger (median age 14 days (6–19 days) versus 25 days (14–33 days); p=0.012), more likely to require ICU admission (p<0.001) and more likely to have disseminated disease (p=0.007). Two (1.8%) infants died and 10 (9%) had neurodevelopmental morbidity. Death or neurodevelopmental morbidity was more likely in those with encephalitis compared to those without (8 (62%) versus 4 (4%); p<0.001)) and in infants with HSV compared to non-HSV (57% vs. 8%; p=0.002), but not any different between HSV and non-HSV encephalitis (p>0.05). Among infants <90 days of age with viral CNS infections, just over 10% have features consistent with encephalitis. These younger infants are also more likely to require ICU support and manifest extra-CNS disease. Although most infants with viral CNS infections have good outcomes, those with encephalitis, regardless of aetiology, should be identified as the ones requiring long-term neurodevelopmental follow-up.