Incidence of Neonatal Herpes Simplex Virus Infections in Two Managed Care Organizations: Implications for Surveillance

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Abstract
Objectives: To estimate the incidence of neonatal herpes simplex virus (HSV) infections and to assess the utility of surveillance methods for neonatal herpes in 2 managed care populations. Methods: We identified potential cases using 15 discharge International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9) codes for neonatal HSV and other diseases clinically consistent with this diagnosis. We also searched laboratory databases for positive HSV tests and investigated deaths during the neonatal period. We performed medical chart review using a standardized form. Two pediatric infectious disease specialists reviewed the forms of infants who had a positive HSV test or received a herpes-related diagnosis and made a determination as confirmed, probable, or not a case. Results: Among 270,703 infants born from 1997 to 2002, we identified 737 potential cases and completed medical chart abstraction for 699 (95%). Final review identified 35 confirmed or probable cases of neonatal HSV, and the incidence was 12.9 per 100,000 live births. Only 24 (69%) of the 35 cases were confirmed by laboratory testing. Among the 24 confirmed cases, 22 (92%) received an ICD-9 code of 054.xx or 771.2. Among the 60 infants that received an ICD-9 code of 054.xx or 771.2, only 31 (52%) were confirmed or probable cases of neonatal HSV after final review. Conclusions: About 30% of neonatal HSV cases were not laboratory confirmed. The use of ICD-9 codes of 054.xx and 771.2 was a sensitive but not specific method to identify cases of neonatal herpes.