Public Health Surveillance Systems

1. Public Health Surveillance Systems

2. Goals • Adverse events surveillance • Syndromic surveillance • Registries • Laboratory data • Review purpose of surveillance • Describe types of state and local surveillance systems: • Vital records • Disease reporting (morbidity data) • Surveys • Sentinel surveillance • Zoonotic disease surveillance • Provide example of public health actions resulting from surveillance data

3. Purpose of Surveillance • Collecting surveillance data has many purposes • Monitoring disease trends • Detecting outbreaks • Providing information to plan public health interventions • Stimulating research

4. Purpose of Surveillance • Specific uses of surveillance data vary depending on organization or agency • National agencies • Monitoring disease trends over time to inform policy • State and local agencies • Assuring accurate diagnosis and treatment of infected persons • Managing people exposed to disease • Detecting outbreaks • Guiding public health prevention and control programs

5. Types of State and Local Surveillance Systems • Surveillance systems used to monitor disease trends and plan public health programs • Vital statistics, disease reporting, surveys • More specialized systems • Sentinel surveillance, zoonotic disease surveillance, adverse events surveillance, syndromic surveillance, disease registries, laboratory surveillance • Some types more useful for certain diseases than others; each fills a specific need

6. Vital Statistics • Records of births and deaths: a basic but critical cornerstone of public health surveillance • Mortality data over past century show decrease in rate of deaths due to infectious diseases; rate of death from non-infectious causes remain steady • Infant mortality rate (number of deaths among infants per 1,000 births) long used as indicator of overall population health • Birth data used to monitor incidence of preterm birth, risk factor for variety of adverse health outcomes

7. Vital Statistics • In United States, vital statistics available from • National Center for Health Statistics • State vital records offices • CDC WONDER – online system containing data on births, deaths, many diseases from Centers for Disease Control and Prevention (CDC)

8. Disease Reporting (Morbidity Data) • Disease reporting required internationally by World Health Organization through International Health Regulations • Smallpox • Wild-type poliomyelitis • Severe acute respiratory syndrome (SARS) • Human influenza caused by new subtypes • Any public health emergency of international concern • Broad definition used to capture any disease, condition, event that could represent international risk

9. Disease Reporting (Morbidity Data) • In the United States, disease reporting mandated by state law • List of reportable diseases varies by state • States report nationally notifiable diseases to CDC on voluntary basis • List of notifiable diseases updated regularly by Council of State and Territorial Epidemiologists and CDC

10. Surveys • Especially useful for monitoring chronic diseases and health-related behaviors • Youth Risk Behavior Survey (YRBS) asks high school students about substance use, sexual behavior, physical activity, nutrition • Results used to monitor trends in health behaviors, plan public health programs, evaluate public health policies at national and state levels

11. Surveys Percent of high school students who reported smoking in the 30 days prior to the survey, United States, 1997-2007 • YRBS shows decline in youth smoking from 36% in 1997 to 20% in 2007

12. Surveys • Other national surveys conducted by CDC: • Behavioral Risk Factor Surveillance System (BRFSS) • National Health Interview Survey (NHIS) • Pregnancy Risk Assessment Monitoring System (PRAMS) • National Health and Nutrition Examination Survey (NHANES)

13. Sentinel Surveillance • Alternative to population-based surveillance, • Involves collecting data from sample of reporting sites (sentinel sites) • Example: Selected health care providers report number of cases of influenza-like illness to state health department on weekly basis • Allows states to monitor trends using relatively small amount of information

14. Graph indicates peak of influenza activity during 2007- 2008 season in late February and early March (Weeks 7-9) Sentinel Surveillance Percentage of visits for influenza-like illness reported by US sentinel provider network, 2006-2007, 2007-2008

15. Sentinel Surveillance • Sentinel providers also used to gather more specific information • Example: sentinel provider network in British Columbia, Canada, used in a study of vaccine effectiveness during 2005-2006 influenza season

16. Zoonotic Disease Surveillance • Surveillance of zoonotic diseases (diseases found in animals that can be transmitted to humans) often involves system for detecting infected animals • Example: 2001 Florida surveillance for West Nile Virus (WNV): • Web site and telephone hotline to report dead birds, some collected and tested for WNV • Mosquitoes collected and tested for WNV in 10 counties • Blood collected from 3-12 sentinel chickens in each of 212 flocks up to 4 times per month, tested for antibodies to WNV • Veterinarians asked to test horses with neurologic symptoms consistent with WNV • Health care providers reminded of reporting and diagnostic criteria for possible human cases of WNV

17. Zoonotic Disease Surveillance • Surveillance systems allowed public health authorities to determine intensity of WNV by geographic area • Detection of WNV led to public health control measures: • Advising public to protect against mosquito bites • Intensifying mosquito abatement efforts

18. Adverse Events Surveillance • Surveillance system focusing on patient safety: Adverse Events Reporting System (AERS), operated by Food and Drug Administration (FDA) • Negative effects experienced by people who received approved drugs, therapeutic agents • Voluntary reports from health care providers (physicians, pharmacists, nurses) and public (patients, lawyers) • Health care providers/patients may report events directly to product manufacturer; manufacturer required to report event to AERS • FDA uses AERS to identify possible safety concerns associated with approved products

19. Adverse Events Surveillance • Vaccine Adverse Events Reporting System (VAERS) also focused on patient safety; operated by CDC with FDA • Like AERS, but for negative effects experienced by people who have received licensed vaccines • Used in 2003 for smallpox vaccines to health care and public health professionals in preparation for bioterrorist attack • >100 adverse events reported after smallpox vaccination, 16 suspect and 5 probable cases of myocarditis or pericarditis • Advisory Committee on Immunization Practices recommended ending vaccination after health care and public health response teams

20. Adverse Events Surveillance • Passive surveillance systems may be limited by underreporting or biased reporting, cannot be used to determine whether a drug or vaccine caused a specific adverse health event • (See FOCUS Volume 5, Issue 5 for definitions of active and passive surveillance) • Used as early warning signals • Possible associations between drugs or vaccines and adverse events examined using well designed epidemiologic study, appropriate action based on results

21. Syndromic Surveillance • Relatively new surveillance method, uses clinical information about disease signs and symptoms, before diagnosis is made • Often use electronic data from hospital emergency rooms

22. Syndromic Surveillance • Example: New York City operates syndromic surveillance system using emergency department chief-complaint data from approximately 44 hospitals • Data monitored electronically for beginning of disease outbreak • In 2002, system detected higher than usual number of diarrheal and vomiting symptoms • Health department notified hospital emergency departments of possible outbreak and collected stool specimens, several tested positive for norovirus

23. Syndromic Surveillance • Example: New York City (continued) • Similar outbreak later that year not detected by the system • Failure to detect attributed to incorrect coding of chief complaint by emergency departments • Illustrates potential benefits of syndromic surveillance, areas where changes needed to increase usefulness of system

24. Registries • Surveillance system used for particular conditions • Often established at state level to collect information about persons diagnosed with condition • Example: cancer registries collect information about type of cancer, anatomic location, stage of disease at diagnosis, treatment, outcomes • Used to improve prevention programs • Example: women in rural areas diagnosed with breast cancer later than women in urban areas; choose to promote mammography screening in rural areas using mobile van

25. Laboratory Data • Public health laboratories routinely conduct tests for viruses, bacteria, other pathogens • In US, labs participate in National Salmonella Surveillance System through electronic reporting of Salmonella isolates • 2006: >40,000 isolates reported • Lab serotyping provides information about cases likely to be linked to common source • Serotypes are useful for detecting local, state, or national outbreaks

26. Laboratory Data • Another lab system: PulseNet by CDC and Association of Public Health Laboratories to monitor foodborne illness outbreaks • Enables labs across US to compare pulsed-field gel electrophoresis (PFGE) patterns of bacteria from ill persons and determine similarity • Allows scientists to determine whether outbreak is occurring, even at geographically distant locations • Can decrease time required to identify outbreaks of foodborne illness and causes

27. Public Health Actions Resulting From Surveillance: Poliomyelitis • Dramatic decrease in paralytic poliomyelitis in US following licensure of inactivated polio vaccine (1955), oral polio vaccine (1961) • Global example: monitoring progress toward eradication of poliomyelitis Number of cases of paralytic poliomyelitis by year, United States, 1967-1997

28. Public Health Actions Resulting From Surveillance: Poliomyelitis • Global example: monitoring progress toward eradication of poliomyelitis (continued) • Using data from countries around world, World Health Organization implemented intensive vaccination programs where decline not as significant

29. Public Health Actions Resulting From Surveillance: HIV/AIDS • Example: surveillance for HIV/AIDS ongoing since detection of disease in the US in 1981 • Data on incidence and prevalence among population subgroups, geographic areas important to guide prevention, control efforts • 2003-2006: estimated number of cases increased among men who have sex with men, remained steady among heterosexuals, decreased among injection drug users • Suggests that prevention programs working more effectively in some groups than others   

30. Mapping rates shows clear pattern of higher risk in southeastern states than in rest of nation Suggests need for more prevention measures in southeast Public Health Actions Resulting From Surveillance: HIV/AIDS Rates of diagnosed HIV/AIDS, by area of residence, United States, 2006

31. Conclusion • Many sources of public health surveillance data at local, state, national levels • Knowing where to look for different types of data can save time and resources • Data used for variety of purposes: • Guiding prevention strategies and targeting resources • Detecting disease outbreaks of local, national, international significance • Evaluating control measures

32. Resources • National Vital Statistics System • Data on births, deaths, marriages, divorces, fetal deaths from all 50 states, 2 cities (Washington, DC, and New York City), 5 territories (Puerto Rico, Virgin Islands, Guam, American Samoa, Commonwealth of the Northern Mariana Islands); much of information available online • http://www.cdc.gov/nchs/nvss.htm • CDC WONDER • User-friendly query system providing public health information on births, deaths, cancer incidence, HIV and AIDS, tuberculosis, vaccinations, census data • http://wonder.cdc.gov/ • Nationally Notifiable Infectious Diseases • List of diseases recommended for states to report to CDC • http://www.cdc.gov/ncphi/disss/nndss/phs/infdis.htm

33. References • Birkhead GS, Maylahn CM. State and local public health surveillance. In: Teutsch SM, Churchill RE, eds. Principles and Practice of Public Health Surveillance. 2nd ed. New York, NY: Oxford University Press; 2000:253-286. • Armstrong GL, Conn LA, Pinner RW. Trends in infectious disease mortality in the United States during the 20th century. JAMA. 1999;281(1):61-66. • World Health Organization. International health regulations (2005). 2nd ed. http://www.who.int/csr/ihr/en/. Published 2008. Accessed October 3, 2008. • Centers for Disease Control and Prevention. Summary of notifiable diseases – United States, 2006. Morb Mortal Wkly Rep. 2008;55(53):1-84. • Centers for Disease Control and Prevention. Cigarette use among high school students – United States, 1991-2007. Morb Mortal Wkly Rep. 2008;57(25):689-691.

34. References • FluView. Outpatient illness surveillance. Centers for Disease Control and Prevention Web site. http://www.cdc.gov/flu/weekly/. Updated October 10, 2008. Accessed October 14, 2008. • Skowronski DM, Masaro C, Kwindt TL, et al. Estimating vaccine effectiveness against laboratory-confirmed influenza using a sentinel physician network: results from the 2005-2006 season of dual A and B mismatch in Canada. Vaccine. 2007;25(15):2842-2851. • Blackmore CGM, Stark LM, Jeter WC, Oliveri RL, Brooks RG, Conti LA, Wiersma ST. Surveillance results from the first west nile virus transmission season in Florida, 2001. Am J Trop Med Hyg. 2003;69(2):141-150. • Food and Drug Administration, Center for Drug Evaluation and Research. Adverse Event Reporting System (AERS) Web site. http://www.fda.gov/cder/aers/default.htm. Published August 7, 2002. Updated September 5, 2008. Accessed November 21, 2008.

35. References • Zhou W, Pool V, Iskander JK, et al. Surveillance for safety after immunization: vaccine adverse events reporting system (VAERS) – United States, 1991-2001. MMWR CDC Surveill Summ. 2003;52(SS-1):1-11. • Centers for Disease Control and Prevention. Update: adverse events following civilian smallpox vaccination – United States, 2003. Morb Mortal Wkly Rep. 2004;53(5):106-107. • Centers for Disease Control and Prevention. Advisory Committee on Immunization Practices (ACIP) statement on smallpox preparedness and vaccination. http://www.bt.cdc.gov/agent/smallpox/vaccination/acipjun2003.asp. Published June 18, 2003. Accessed October 23, 2008. • Steiner-Sichel L, Greenko J, Heffernan R, Layton M, Weiss D. Field investigations of emergency department syndromic surveillance signals – New York City. Morb Mortal Wkly Rep. 2004;53(suppl):190-195.

36. References • Centers for Disease Control and Prevention. Salmonella surveillance: annual summary, 2006. http://www.cdc.gov/ncidod/dbmd/phlisdata/salmonella.htm. Published 2008. Accessed October 14, 2008. • Swaminathan B, Barrett TJ, Fields P. Surveillance for human salmonella infections in the United States. J AOAC Int. 2006;89(2):553-559. • Centers for Disease Control and Prevention. What is PulseNet? PulseNet Web site. http://www.cdc.gov/pulsenet/whatis.htm. Published July 24, 2006. Accessed December 3, 2008. • Centers for Disease Control and Prevention. Summary of notifiable diseases, United States, 1997. Morb Mortal Wkly Rep. 1998;46(54):1-87. • Centers for Disease Control and Prevention. HIV/AIDS Surveillance Report, 2006. Vol. 18. http://www.cdc.gov/hiv/topics/surveillance/resources/reports/. Published 2008. Accessed October 14, 2008.