Herpes simplex virus infections in preterm infants

OBJECTIVE. Neonatal herpes simplex virus infections cause significant neonatal mortality and morbidity, but the course and prognosis in preterm infants is not well documented. We performed a retrospective review of herpes simplex virus infections at out institution within the first 30 days after birth in infants who were born at < 37 weeks to help better define the symptoms and signs of herpes simplex virus infections in preterm infants and to assist in prognosis. METHODS. Hospital databases were reviewed to identify culture- or polymerase chain reaction-proven cases of herpes simplex virus-1 or herpes simplex virus-2 infections that occurred in preterm newborns between 1989 and 2003. Maternal and neonatal histories, clinical features, and laboratory results were reviewed systematically. RESULTS. Ten preterm singletons and a set of twins were infected with herpes simplex virus-2 during the first month after birth. No mother had herpes simplex virus lesions at delivery, but a history of genital herpes simplex or other sexually transmitted infections was prevalent among the mothers. Infants presented with either disseminated disease or encephalitis. All infants with disseminated disease (n = 9) died, whereas the 3 infants with encephalitis survived. All infants in the cohort developed respiratory distress, and consistent with the prominence of respiratory symptoms, viral cultures of the respiratory tract were consistently positive. Ten of 12 infants received acyclovir, but despite treatment within 48 hours of symptoms, infants with disseminated disease deteriorated rapidly and died. Two of 3 infants who received high-dosage (60 mg/kg per day) acyclovir survived. CONCLUSIONS. Herpes simplex virus infections in preterm infants usually present during the first 2 weeks of life with respiratory distress and a high incidence of disseminated disease. Viral respiratory cultures have a high yield for documentation of infection. The morbidity of herpes simplex virus in this population may be attributable to a relatively immature immune system in this population. Additional studies are necessary to delineate the evolution of herpes simplex virus disease in preterm infants and the role of antiviral therapy in mitigating the sequelae of herpes simplex virus infections in this population.