Bauer, Heidi M. MD, MS, MPH
Neonatal herpes can be a devastating disease and is one of the most important complications related to genital infection.1 Further, there is general consensus that accurate, feasible, and ongoing surveillance of neonatal herpes would be extremely valuable. However, before mandated case reporting can be fully endorsed, a number of questions need to be addressed:
* Will the data be valid (i.e., accurately represent the epidemiology)?
* How will the data be used in terms of assessment and program evaluation?
* What are the public resources necessary to ensure robust ongoing surveillance?
* Will the gains in population health justify the effort?
* What are alternative surveillance and/or research methods for achieving the same goals?
Considerations for making neonatal herpes reportable to public health authorities were nicely outlined by Handsfield et al. and included incidence, epidemiologic stability, severity, potential to spread, socioeconomic burden, preventability, potential to drive public health policy, risk perception, other sector interest, and international considerations.2 Neonatal herpes clearly meets many of these criteria. In particular, infection can be life-threatening and survivors may suffer severe neurologic and developmental disabilities that result in significant socioeconomic burdens. Further, the incidence is comparable to other congenital diseases for which case reporting is mandated (e.g., rubella and syphilis). However, these criteria fail to address questions related to data validity, cost-benefit, and alternative surveillance strategies.
National leadership and coordination are critical for developing high-quality sustainable surveillance strategies for neonatal herpes. In 1999, an expert panel convened by the Centers for Disease Control and Prevention recommended that surveillance demonstration projects for neonatal herpes be initiated to explore the efficacy and feasibility of various approaches to surveillance3; however, little progress has been made in the past 10 years. In fact, only 7 papers have been published specifically examining neonatal herpes surveillance in the United States.4–10 Further, although a standardized case definition is essential for generating incidence estimates that are comparable across geographic areas and over time,11 national consensus has yet to be achieved. Regardless, as a result of the Council of State and Territorial Epidemiologists efforts,12 several jurisdictions with neonatal herpes surveillance programs currently use a standard case definition (C. Lohff, personal communication, 2011).
Unlike research, which relies on representative sampling and methods to generalize findings to larger populations, case-based surveillance systems rely on complete reporting to document all cases and calculate accurate population-based incidence using census data as the denominator. Despite public health powers to mandate reporting, evaluating and ensuring compliance with legal mandates is challenging and can be resource-intensive.13 Obtaining accurate counts is particularly important for rare conditions because incomplete reporting could result in underestimates of incidence, artificial fluctuations over time, or inaccurate demographic and clinical correlates, which could ultimately undermine prevention efforts and waste public health resources.
Incidence estimates of neonatal herpes vary from 4 to 31 per 100,000 live births depending on the sources of data. The highest estimate was derived from a prospective cohort study in Washington state from 1982 to 1999.14 Secondary analyses of hospital discharge data using International Classification of Diseases (ICD)-9 terms to identify cases have resulted in moderate estimates ranging from 8.4 to 12.9 per 100,000.4–7,15 Case-based surveillance has produced the lowest estimates: 4 per 100,000 in 9 US states with neonatal herpes as a reportable condition in 2000–20058 and 5.9 per 100,000 in Canada from 2000 to 2003.16 In addition to methodologic differences, the variability in incidence estimates is likely related to differences in case definition, including diagnostic codes included, limits on patient age in days, and requirements for laboratory confirmation; differences in populations studied in terms of geographic locations and clinical settings; and differences in the study timeframe. That said, there is little evidence that rates of either genital herpes infection or neonatal infection have changed markedly in the past 3 decades.6,17
In this issue of Sexually Transmitted Diseases, Handel et al. compare incidence estimates and clinical correlates of neonatal herpes in New York City (NYC) using 2 sources of data: mandated case-based reporting implemented in 2006 and hospital discharge data.18 Mandated case reporting from 2006 to 2010 produced an average annual incidence of 13.3 per 100,000; whereas analysis of hospital discharge data from 1997 to 2008 produced annual rates from 5.6 to 18.3 (median, 11.8) per 100,000. Not only is this the highest neonatal herpes incidence reported from case-based surveillance, it appears to correlate well with hospital discharge data. From 2006 to 2008, 47 cases were identified using hospital discharge data, whereas mandated reporting identified 53 cases, a 13% improvement in sensitivity (Handel et al., Fig. 1). This report may be the first to describe a high quality case-based surveillance system for neonatal herpes in the United States.
In addition to determining overall incidence, the authors were able to document epidemiologic and clinical correlates of neonatal herpes. In 4 1/2 years of case-based surveillance, 76 cases were detected and investigated. Investigations included review of infant and maternal medical records, telephone interviews with providers, and for some cases, interviews with parents. This intensive case investigation allowed for the collection and analysis of extensive demographic and clinical data. The authors provide a detailed and interesting account of this case series in terms of obstetric risks and management, clinical manifestations of infection, dates of symptom onset and diagnosis, diagnostic testing, HSV type, demographic and clinical correlates by HSV type, management, and outcomes. Findings were compared to published literature, which allowed the authors to make inferences regarding potential prevention strategies. The authors conclude that although mandated case-based reporting may be more labor-intensive, it is superior to using existing administrative data because it is timely, provides specific case identification, and allows collection of comprehensive case data.
Because key sociodemographic data are typically available for the overall population, case-based surveillance is useful in identifying groups at higher risk on the basis of age and race/ethnicity. However, determining clinical and behavioral risk factors and measuring the effectiveness of clinical prevention strategies is more challenging. Collection of the detailed clinical data described by Handel et al. was undoubtedly resource-intensive, requiring many hours of medical record review and interviewing, as well as special training of field staff. Yet, the lack of appropriate control groups is an inherent limitation of case-based surveillance data. The public costs of mandated case reporting include implementation to ensure awareness and cooperation among providers and laboratories, case investigation, and data management and analysis. Reporting also requires an investment of resources on the part of hospitals, laboratories, and medical professionals. Although neonatal herpes is relatively uncommon, these costs need to be balanced with the expected benefits. Recent progress toward electronic laboratory reporting may have a dramatic effect on reducing costs for both reporting sources and public health departments.
Justifying the resources necessary for a reliable ongoing surveillance system depends on understanding the potential for gains in population health. These gains are driven by (1) the preventability, or theoretical preventable proportion, of disease; (2) the use of surveillance data to drive prevention programs; and (3) the effectiveness of methods to implement prevention programs. Current methods for neonatal herpes prevention include improved diagnostic testing and treatment for primary herpes infection in symptomatic pregnant women, cesarean delivery in women with evidence of genital herpes at term, antiviral agents for women with a history of genital herpes to reduce the risk of a recurrence and shedding at term, and minimizing the use of invasive monitoring devices and delivery instruments in at-risk women.19 While these obstetric interventions are primarily focused on reducing neonatal herpes in infants born to women with pre-existing infection, the risk of transmission is highest among women who acquire genital infection during pregnancy.20,21 Although tools are available for screening pregnant women (and their partners) using serology tests to identify those at risk, offering counseling about avoiding unprotected sexual contact, and treating partners to reduce shedding and transmission, the effectiveness of these tools has not been demonstrated.1,22 Of course, the most promising approach involves development of effective vaccines to reduce the incidence of herpes infection in the population. Surveillance data will be beneficial for establishing a baseline, and also monitoring the population-based impact once effective prevention strategies are identified and implemented.
Handsfield et al. argue that making neonatal herpes a reportable condition may increase awareness, stimulate interest, and drive public health policy and clinical practice such that clinical outcomes may be improved by earlier diagnosis and treatment, prevention research may be better funded, and general STD prevention and control efforts may be more effective.2 In particular, because genital herpes affects a broad segment of the population, including those seemingly at low risk for STD, greater visibility may overcome some of the stigma attached to STDs in general. Although this argument has merit, it is unclear whether mandated case reporting is the most effective means to these ends.
The fact that a substantial proportion of neonatal herpes is caused by HSV-1, which may be transmitted during pregnancy through oral-genital contact or transmitted to the neonate after birth, makes prevention even more challenging. Handel et al. documented a nontrivial (4/76, 5%) proportion of cases associated with ritual Jewish circumcision. Interestingly, the occurrence of neonatal herpes in relation to this religious practice was documented before the establishment of NYC's surveillance.23,24 The NYC health department took public health action in 2005 in the form of an open letter to the Jewish community25 and a provider alert,26 and continues to provide web-based information to the public.27 Ongoing surveillance may prove useful in monitoring the trends in neonatal herpes associated with this practice and assessing the effectiveness of interventions.
Mandating case reporting would not be necessary or justified if alternative sources of high-quality data were available; however, administrative data have been criticized for not being timely, lacking sociodemographic data and clinical details, relying on nonspecific diagnostic codes to identify case, and presenting challenges with data linking and deduplication across providers and databases.6,7 With the development and widespread adoption of electronic medical records, ICD-10 codes with improved specificity for neonatal herpes, and electronic laboratory reporting, many of these deficiencies may be overcome. Clearly, case definitions based on ICD-9 and ICD-10 codes need to be standardized across surveillance projects. Rather than dismissing existing data that do not adequately meet disease surveillance needs and creating parallel duplicative systems for surveillance, it may be possible to work across government agencies to supplement ongoing data collection with disease-specific variables. As several adverse health effects of STDs involve neonatal transmission, closer collaboration with efforts to monitor maternal and infant health may be warranted. With dwindling public health resources, existing data collection infrastructure should be fully exploited.
Unqualified support for mandated case reporting for neonatal herpes is premature for 3 basic reasons. First, unless significant resources are expended, incidence may be grossly underestimated. Second, it is unclear whether neonatal herpes surveillance data will translate to effective prevention programs and disease reduction. Third, additional effort is warranted in using existing medical data, particularly in light of advances in health information technology. Of course, these issues should not diminish the accomplishments of the NYC health department in creating a high-quality surveillance program for neonatal herpes, which may well serve as a model for other health jurisdictions. Ideally, further analysis will be conducted on actual costs of the system and impact of interventions to prevent neonatal herpes.
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