Neonatal herpes simplex virus infections in Canada: results of a 3-year national prospective study.

Objective: The goal was to determine incidence, determinants, and morbidity and mortality rates of neonatal herpes simplex virus infections in Canada.

Methods: From October 1, 2000, to September 30, 2003, reports of neonatal herpes simplex virus infection were solicited actively from all Canadian pediatricians and pediatric subspecialists on a monthly basis.

Results: Fifty-eight cases of neonatal herpes simplex virus were reported (5.9 cases per 100,000 live births). Cesarean section was performed in 24.6% of cases, 28.1% of patients were born prematurely, 28.6% had birth weights of < 2500 g, and 7.5% had Apgar scores of < 7 at 5 minutes of life. Mothers < 20 years of age and those reporting Aboriginal ethnicity were affected disproportionately; 40% of mothers had no history of genital herpes before delivery, and intrapartum genital lesions were present in only 1 of 58 cases. Of cases with known herpes simplex virus type, 62.5% were herpes simplex virus-1. Localized infections accounted for 59.6% of cases, whereas disseminated disease and central nervous system disease were reported for 17.5% and 22.8%, respectively. Localized infections were more likely to be herpes simplex virus-1 and disseminated and central nervous system infections herpes simplex virus-2. Nine of 58 cases were fatal. All cases with known treatment information (n = 55) were treated with intravenously administered acyclovir.

Conclusions: This is the first study to examine the national incidence of neonatal herpes simplex virus in Canada. Many women had no genital herpes simplex virus history before delivery, and the majority of cases were herpes simplex virus-1, which has implications for prenatal screening and vaccine/drug development. Follow-up monitoring of case subjects is being performed annually for 3 years, to be completed in October 2006.