Study: Prevalence of neonatal HSV versus other infections

October 1, 2008

Study: Should herpes simplex virus be considered in the differential diagnosis of neonatal fever and hypothermia?

Investigators set out to determine how the prevalence of herpes simplex virus (HSV) infection in neonates compares with the prevalence of other viral infections and serious bacterial infections in newborns. They conducted a retrospective investigation in 5,800 neonates evaluated in the emergency department with any chief complaint who were admitted to a children's hospital in Texas during a five-year period. Median age of the infants was 15 days, with median length of hospital stay three days.

Of total neonates, 8.6% had a viral infection (8.4% non-HSV and 0.2% HSV) and 4.6% a serious bacterial infection. Of the 960 neonates who were febrile, 17.2% had viral infections, and 14.2% had serious bacterial infections. Non-HSV viral infection was the most common type of infection. The highest HSV prevalence (0.6%) was in infants in the second week of life. The prevalence of HSV infection, which did not differ with the season, was not statistically different in neonates who were hypothermic, normothermic, and febrile.

A total of 499 viral pathogens were identified in the study population, of which 10 (2.0%) were HSV. The most common pathogens were respiratory syncytial virus (46.7%), rhinovirus (16.0%), and enterovirus (13.4%). Of the 10 neonates with HSV infection, three had disseminated disease, three had central nervous system disease, and four had skin, eye, and mouth HSV disease. Of the 269 neonates with serious bacterial infection, 21 had meningitis, 71 bloodstream infection, and 177 urinary tract infection.

Commentary

Read this article, and the two accompanying editorials by Drs. Sarah Long and David Kimberlin. Together they explain why we worry about this uncommon but serious, treatable disease. They also show how experts, looking at the same data but in different settings and with different experience, can make different clinical decisions. I have gotten more conservative over the years, lowering my threshold for use of acyclovir. This is in part because of increased availability of polymerase chain reaction and HSV culture to help determine when to stop therapy.

Dr. Long defines a conservative approach by describing seven situations for which she recommends initiating acyclovir in a sick neonate. The situations include: When HSV is suspected due to, for example, vesicles, seizures, or elevated liver function tests; when babies present with sepsislike syndrome with or without hypothermia; when infants appear more ill than would be explained by another diagnosis; when a child presents with illness before the 21st day of life; when a neonate presents with mononuclear cell pleocytosis in cerebrospinal fluid during any season or fever of 38° C or higher without another explanation; and when persistent or recurrent erythema, purulence, or crusting at a scalp electrode site is present. I'll keep this list with me on the inpatient ward.

DR. BURKE, section editor for Journal Club, is chairman of the department of pediatrics at Saint Agnes Hospital, Baltimore. He is a contributing editor for Contemporary Pediatrics. He has nothing to disclose in regard to affiliations with, or financial interests in, any organization that may have an interest in any part of this article.