Samuel L. Groseclose

Evaluation of reporting timeliness of public health surveillance systems for infectious diseases

BackgroundTimeliness is a key performance measure of public health surveillance systems. Timeliness can vary by disease, intended use of the data, and public health system level. Studies were reviewed to describe methods used to evaluate timeliness and the reporting timeliness of National Notifiable Diseases Surveillance System (NNDSS) data was evaluated to determine if this system could support timely notification and state response to multistate outbreaks.MethodsPublished papers that quantitatively measured timeliness of infectious disease surveillance systems operating in the U.S. were reviewed. Median reporting timeliness lags were computed for selected nationally notifiable infectious diseases based on a state-assigned week number and various date types. The percentage of cases reported within the estimated incubation periods for each disease was also computed.ResultsFew studies have published quantitative measures of reporting timeliness; these studies do not evaluate timeliness in a standard manner. When timeliness of NNDSS data was evaluated, the median national reporting delay, based on date of disease onset, ranged from 12 days for meningococcal disease to 40 days for pertussis. Diseases with the longer incubation periods tended to have a higher percentage of cases reported within its incubation period. For acute hepatitis A virus infection, which had the longest incubation period of the diseases studied, more than 60% of cases were reported within one incubation period for each date type reported. For cryptosporidiosis, Escherichia coli O157:H7 infection, meningococcal disease, salmonellosis, and shigellosis, less than 40% of cases were reported within one incubation period for each reported date type.ConclusionPublished evaluations of infectious disease surveillance reporting timeliness are few in number and are not comparable. A more standardized approach for evaluating and describing surveillance system timeliness should be considered; a recommended methodology is presented. Our analysis of NNDSS reporting timeliness indicated that among the conditions evaluated (except for acute hepatitis A infection), the long reporting lag and the variability across states limits the usefulness of NNDSS data and aberration detection analysis of those data for identification of and timely response to multistate outbreaks. Further evaluation of the factors that contribute to NNDSS reporting timeliness is warranted.

The Changing Epidemiology of Syphilis

AFTER DECLINING EVERY YEAR since 1990, and less than 2 years after the launching of the National Plan to Eliminate Syphilis in the United States, rates of primary and secondary syphilis increased slightly in 2001.1 New epidemics involving men who have sex with men (MSM) have since been detected in most major US cities. If we could identify the persons who are most likely to acquire the next syphilis infections and why, we might be able to reach them early and prevent acquisition or reach them soon after they are infected and treat them before they transmit to others. This requires identifying characteristics of persons acquiring infection, how they are meeting partners, and how they are transmitting infection. When this information is known, we can warn the population at risk so they can take precautions to avoid infection or perhaps recognize an infection when they get it. We can also more effectively target screening campaigns and alert health care workers to look for infections among persons at risk. We also want to know how large the current syphilis epidemic will become because it will help with resource allocation decisions. Interventions early in an epidemic may halt transmission that could otherwise eventually become highly magnified. However, effective interventions can be expensive, even early in an epidemic. It is easier to justify extensive interventions for an epidemic that would otherwise grow to millions of cases (e.g., acquired immunodeficiency syndrome [AIDS]) than it is for an epidemic that would ultimately involve a small number of cases (e.g., hantavirus pulmonary syndrome). Finally, we want to know what this epidemic is telling us about other sexually transmitted infections, particularly human immunodeficiency virus (HIV). There has been concern that advances in antiretroviral therapy were leading to disinhibition of the sexual behaviors that were changed due to the AIDS epidemic.2,3 A relaxation of safe-sex practices could lead to resurgence of HIV and AIDS; however, increases in HIV transmission can be very difficult to identify because of the long and variable incubation period. Thus, other indicators have been used to try to identify effectiveness of HIV prevention programs.4 Some studies have suggested there have been increases in unprotected anal sex.3,5,6 Other studies suggest gonorrhea rates have increased among MSM.6,7 Is the current syphilis epidemic another indication that HIV transmission is increasing? We will address these questions by reviewing surveillance data reported to CDC and published epidemiologic research from the United States and elsewhere.

Estimated incidence and prevalence of genital Chlamydia trachomatis infections in the United States, 1996.

BACKGROUND AND OBJECTIVE Because genital Chlamydia trachomatis infections and their sequelae have a major impact on individuals and the health care system, it is important to periodically update estimates of chlamydia incidence and prevalence in the United States. STUDY DESIGN Chlamydia incidence and prevalence were estimated using: (1) a method based on estimates of population-specific chlamydia prevalence, and (2) a method based on the chlamydia-to-gonorrhea case rate ratio. RESULTS Using the prevalence-based method, point prevalence among persons 15 to 44 years of age was estimated to be 1.6 million chlamydial infections, and annual incidence, 2.4 million cases per year. Using a method based on the ratio of reported gonorrhea to chlamydia, incidence was estimated to be 2.8 million infections per year, and prevalence, 1.9 million. Adjustment for sensitivity of diagnostic tests yielded annual incidence estimates of 2.5 to 3.3 million infections. CONCLUSIONS Using two methods, we estimated the annual incidence of chlamydial infections in the United States among persons 15 to 44 years of age to be approximately 3 million infections. Critical data needed for more precise estimates include: sensitivity of current diagnostics, better data on infections in males, the current extent of underdetection and underreporting, and better data on duration of infection in men and women.

Endemic, Notifiable Bioterrorism-Related Diseases, United States, 1992–1999

Little information is available in the United States regarding the incidence and distribution of diseases caused by critical microbiologic agents with the potential for use in acts of terrorism. We describe disease-specific, demographic, geographic, and seasonal distribution of selected bioterrorism-related conditions (anthrax, botulism, brucellosis, cholera, plague, tularemia, and viral encephalitides) reported to the National Notifiable Diseases Surveillance System in 1992–1999. Tularemia and brucellosis were the most frequently reported diseases. Anthrax, plague, western equine encephalitis, and eastern equine encephalitis were rare. Higher incidence rates for cholera and plague were noted in the western United States and for tularemia in the central United States. Overall, the incidence of conditions caused by these critical agents in the United States is low. Individual case reports should be considered sentinel events. For potential bioterrorism-related conditions that are endemic and have low incidence, the use of nontraditional surveillance methods and complementary data sources may enhance our ability to rapidly detect changes in disease incidence.

An ecological analysis of sociodemographic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties

Identifying county-level sociodemographic and economic factors associated with the incidence of enteric disease may provide new insights concerning the dynamics of community transmission of these diseases as well as opportunities for prevention. We used data from the National Notifiable Diseases Surveillance System, the U.S. Census Bureau, and the Health Resources and Services Administration to conduct an ecological analysis of 26 sociodemographic and economic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties for the period 1993 to 2002. Our study indicates that race, ethnicity, place of residence, age, educational attainment, and poverty may affect the risk of acquiring one of these enteric bacterial diseases. The lack of specificity of information regarding salmonellae and shigellae serotypes may have led to less specific associations between community-level determinants and reported incidence of those diseases. Future ecological analyses should use serotype-specific data on incidence, which may be available from laboratory-based surveillance systems.

Characterization of patients accepting and refusing routine, voluntary HIV antibody testing in public sexually transmitted disease clinics.

BACKGROUND AND OBJECTIVES To determine the proportion of HIV-infected sexually transmitted disease (STD) clinic patients identified during routine, voluntary HIV counseling and testing and to characterize patients accepting and refusing counseling and testing, we linked data from a blinded HIV seroprevalence survey to data from the HIV counseling and testing program. GOAL OF THIS STUDY This study characterizes patients accepting and refusing routine HIV counseling and testing in two public STD clinics. STUDY DESIGN A cross-sectional, blinded HIV seroprevalence survey was conducted of 1,232 STD clinic patients offered HIV counseling and testing. RESULTS HIV seroprevalence was higher among patients who refused voluntary testing (7.8% versus 3.6%, P = 0.001). Patients who refused testing were more likely to report a prior HIV test (45.6% versus 27.2%; P < 0.001). Among patients reporting a prior HIV test, differences were noted between reported prior results, both positive and negative, and blinded results. CONCLUSIONS HIV-infected STD patients may not be detected by routine HIV testing, and self-reported HIV results should be confirmed.

Prevalence of genital chlamydial infection in young women entering a national job training program 1990 -1997.

OBJECTIVES This analysis describes trends in the prevalence of genital chlamydial infection in economically disadvantaged young women entering a national job training program. METHODS We examined chlamydia test data for May 1990 through June 1997 for women aged 16 to 24 years who enrolled in the program. The significance of trends was evaluated with the chi 2 test for trend. RESULTS Prevalence of chlamydial infection declined 32.9%, from 14.9% in 1990 to 10.0% in 1997 (P < .001). Prevalence decreased significantly in all age groups, racial/ethnic groups, and geographic regions. CONCLUSIONS The decrease in prevalence of chlamydial infection suggests that prevention activities have reached disadvantaged women across the United States; however, prevalence of chlamydial infection remains high, and enhanced prevention efforts in disadvantaged communities are urgently needed.

Application of change point analysis to daily influenza-like illness emergency department visits

Background The utility of healthcare utilization data from US emergency departments (EDs) for rapid monitoring of changes in influenza-like illness (ILI) activity was highlighted during the recent influenza A (H1N1) pandemic. Monitoring has tended to rely on detection algorithms, such as the Early Aberration Reporting System (EARS), which are limited in their ability to detect subtle changes and identify disease trends. Objective To evaluate a complementary approach, change point analysis (CPA), for detecting changes in the incidence of ED visits due to ILI. Methodology and principal findings Data collected through the Distribute project (isdsdistribute.org), which aggregates data on ED visits for ILI from over 50 syndromic surveillance systems operated by state or local public health departments were used. The performance was compared of the cumulative sum (CUSUM) CPA method in combination with EARS and the performance of three CPA methods (CUSUM, structural change model and Bayesian) in detecting change points in daily time-series data from four contiguous US states participating in the Distribute network. Simulation data were generated to assess the impact of autocorrelation inherent in these time-series data on CPA performance. The CUSUM CPA method was robust in detecting change points with respect to autocorrelation in time-series data (coverage rates at 90% when −0.2≤ρ≤0.2 and 80% when −0.5≤ρ≤0.5). During the 2008–9 season, 21 change points were detected and ILI trends increased significantly after 12 of these change points and decreased nine times. In the 2009–10 flu season, we detected 11 change points and ILI trends increased significantly after two of these change points and decreased nine times. Using CPA combined with EARS to analyze automatically daily ED-based ILI data, a significant increase was detected of 3% in ILI on April 27, 2009, followed by multiple anomalies in the ensuing days, suggesting the onset of the H1N1 pandemic in the four contiguous states. Conclusions and significance As a complementary approach to EARS and other aberration detection methods, the CPA method can be used as a tool to detect subtle changes in time-series data more effectively and determine the moving direction (ie, up, down, or stable) in ILI trends between change points. The combined use of EARS and CPA might greatly improve the accuracy of outbreak detection in syndromic surveillance systems.

Traditional Sexually Transmitted Disease Prevention and Control Strategies: Tailoring for African American Communities

African Americans carry the largest disease burden for bacterial sexually transmitted diseases (STDs) in the United States. These infections can have a devastating impact on sexual and reproductive health if they are not diagnosed and treated. Traditionally, public health efforts to prevent and control bacterial STDs have been through surveillance, clinical services, partner management, and behavioral intervention strategies. However, the persistence of disparities in STDs indicates that these strategies are not achieving sufficient impact in African American communities. It may be that factors such as limited access, acceptability, appropriateness, and affordability of services reduce the efficacy of these strategies for African American communities. In this article we describe the STD prevention strategies and highlight the challenges and implications of these strategies in addressing disparities in African American communities.

PHSkb: A knowledgebase to support notifiable disease surveillance

BackgroundNotifiable disease surveillance in the United States is predominantly a passive process that is often limited by poor timeliness and low sensitivity. Interoperable tools are needed that interact more seamlessly with existing clinical and laboratory data to improve notifiable disease surveillance.DescriptionThe Public Health Surveillance Knowledgebase (PHSkb™) is a computer database designed to provide quick, easy access to domain knowledge regarding notifiable diseases and conditions in the United States. The database was developed using Protégé ontology and knowledgebase editing software. Data regarding the notifiable disease domain were collected via a comprehensive review of state health department websites and integrated with other information used to support the National Notifiable Diseases Surveillance System (NNDSS). Domain concepts were harmonized, wherever possible, to existing vocabulary standards. The knowledgebase can be used: 1) as the basis for a controlled vocabulary of reportable conditions needed for data aggregation in public health surveillance systems; 2) to provide queriable domain knowledge for public health surveillance partners; 3) to facilitate more automated case detection and surveillance decision support as a reusable component in an architecture for intelligent clinical, laboratory, and public health surveillance information systems.ConclusionsThe PHSkb provides an extensible, interoperable system architecture component to support notifiable disease surveillance. Further development and testing of this resource is needed.