584 - Epidemiology of Neonatal Herpes Simplex Virus Infection 2008-2023

Publication Number: 584.4905

Tara L. Greenhow, kaiser permanente - san francisco medical center, San Francisco, CA, United States; Zahra Samiezade-Yazd, Kaiser Permanente Division of Research, Pleasanton, CA, United States; Lea Bornstein, Kaiser Permanente - Oakland Medical Center, Oakland, CA, United States; Beverly Young, Kaiser Foundation Hospital - Roseville Women's and Children's Services, Roseville, CA, United States; Tran Nguyen, Kaiser Foundation Hospital - Roseville Women's and Children's Services, Roseville, CA, United States

Background: Rates of neonatal herpes simplex virus (HSV) infections are relatively low, ranging from 1.7 to 13.4 cases per 100,000 live births. Studies reporting the incidence of HSV have been limited by inadequate study size and use of diagnosis codes in the absence of microbiology data.

Objective: In a large integrated health care system in northern California, we reviewed all cases of neonatal HSV and aimed to report incidence rates and trends.

Design/Methods: This was an observational, data-only retrospective study of infants 0-42 days of age born in our health care facilities between October 1, 2008 and September 30, 2023. The primary outcome was HSV disease, which was identified from microbiology records for positive HSV PCR, HSV viral culture, viral culture and/or HSV DFA. We extracted demographic, clinical, and laboratory data from the electronic health record. Manual chart review was conducted to identify clinical symptoms and type of HSV disease. Mucocutaneous disease (SEM), disseminated disease and meningoencephalitis (CNS) were defined using accepted standards. HSV 1 or HSV 2 was identified.

Results: In our 15 year cohort of 593,413 infants there were 59 cases of HSV disease with an incidence rate of 9.9 (95% CI 7.6-12.8) per 100,000 births. Of those, 53% were female and 20% were premature. (Table) Three asymptomatic infants born to mothers with active genital HSV were HSV positive when screened. SEM disease was most common occurring in 31 (53%). The incidence rates of SEM, disseminated and CNS disease were 5.2 (95% CI 3.6-7.4), 2.4 (95% CI 1.3-4.0) and 1.9 (95% CI 0.9-3.3) per 100,000 births, respectively. The trend by type of HSV disease suggests a decrease in SEM disease and an increase in disseminated disease. (Figure 1) HSV-1 disease occurred in 61% and the distribution appeared stable. (Figure 2)
Clinical data available from October 1, 2011 to September 30, 2023 in 51 infants found 4 (8%) were hypothermic, all with persistent hypothermia, and 11 (22%) were febrile. Skin, eye and mouth lesions / vesicles were the most common presentation occurring in 51%. Fever or hypothermia occurred in 2 infants with SEM. Sixteen infants presented ill appearing including 9 with disseminated disease, 7 with CNS disease, and all 5 infants who died.

Conclusion(s): In a birth cohort of almost 600,000 infants, the incidence rate of HSV disease was 10 per 100,000 births and remained stable over the 15 year study period. Ill appearance was common in infants with disseminated and CNS disease and universal in all infants who died. Given the low rates of HSV disease, additional studies are needed to identify at risk infants.

Table
Characteristics of infants with HSV disease 2008-2023

Figure 1
Trends in HSV disease over time

Figure 2
Trends in HSV type over time