Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 1: Introduction
Hello, and welcome to module 7, public health surveillance. My name is Krissy Simeonsson and I’m an assistant professor in the Department of Public Health Surveillance Public Health Surveillance Pediatrics and Public Health at the Brody School
Developed through the APTR Initiative to Enhance Prevention and Population HealthDeveloped Education through in collaborationthe APTR Initiative with the to BrodyEnhance School Prevention of Medicine and Populationat East of Medicine. CarolinaHealth UniversityEducation inwith collaboration funding from with the the Centers Brody forSchool Disease of Medicine Control andat East PreventionCarolina University with funding from the Centers for Disease Control and Prevention
Slide 2: Acknowledgements
This education module is made possible through APTRAPTR wishes wishes to to acknowledge acknowledge the the following following individuals individuals that that developeddeveloped this this module: module: the Centers for Disease Control and Prevention, KristinaKristina Simeonsson, Simeonsson, MD, MD, MSPH MSPH Department of Public Health Department of Public Health Brody School of Medicine at East Carolina University Brody School of Medicine at East Carolina University and the Association for Prevention Teaching and
JulieJulie Daugherty, Daugherty, MPH MPH Department of Public Health Department of Public Health Research cooperative agreement. APTR wishes Brody School of Medicine at East Carolina University Brody School of Medicine at East Carolina University to acknowledge the following individuals that This education module is made possible through the Centers for Disease Control and Prevention (CDC) and the AssociationThis education for Prevention module is Teachingmade possible and Research through the(APTR) Centers Cooperative for Disease Agreement, Control and No. Prevention 5U50CD300860. (CDC) and The the module representsAssociation the for opinions Prevention of the Teaching author(s) and and Research does not (APTR) necessarily Cooperative represent Agreement, the views ofNo. the 5U50CD300860. Centers for Disease The module Controlrepresents and Prevention the opinions or of the the Association author(s) and for Preventiondoes not necessarily Teaching and represent Research. the views of the Centers for Disease Control and Prevention or the Association for Prevention Teaching and Research. developed this module.
Slide 3: Presentation Objectives
Through the course of this presentation we will 1.1. DefineDefine surveillance surveillance 2.2. DiscussDiscuss the the uses uses of of surveillance surveillance start with defining surveillance, then we’ll 3.3. ReviewReview notifiable notifiable disease disease surveillance surveillance 4.4. DescribeDescribe surveillance surveillance limitations limitations discuss some of the uses of surveillance, we’ll spend some time reviewing notifiable disease surveillance, and then finally describe some of surveillance’s limitations.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 4: Surveillance – Information for Action
Surveillance is basically information for action. This slide displays the 3 public health core functions, assessment, policy development, and assurance, which you can see on the outside of the circle. The multi-colored pieces in the center represent the 10 Essential Public Health Services.
Source: http://www.health.gov/phfunctions/public.htm Source: http://www.health.gov/phfunctions/public.htm Surveillance activity occurs as part of the assessment pieces; monitoring health, and diagnosing and investigating disease, or health problems. Good surveillance provides data needed to give an accurate assessment of the status of health in a given population. Good surveillance can also provide an early warning of disease problems, so immediate control measures can be put into place. It can also give us information to design and plan public health programs, and also information to plan and conduct research.
Slide 5: Surveillance
We mentioned previously that surveillance is TheThe ongoing ongoing systematic systematic collection, collection, analysis, analysis, and and interpretationinterpretation of of health health data, data, essential essential to to the the information for action, but on this slide a more planning,planning, implementation, implementation, and and evaluation evaluation of of public public healthhealth practice, practice, closely closely integrated integrated with with the the timely timely formal definition of surveillance is displayed. disseminationdissemination to to those those who who need need to to know. know. Surveillance as defined by the Centers for Disease Control and Prevention is the ongoing systematic collection, analysis, and www.cdc.gov www.cdc.gov interpretation of health data, essential to planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination to those who need to know.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 6: Sources of Surveillance Data
NotifiableNotifiablediseasesdiseases Where does surveillance data come from? There VitalVital records records EnvironmentalEnvironmental monitoring monitoring systems systems are many sources of surveillance data available. AnimalAnimal health health data data IndividualsIndividuals This slide is only a partial listing of some of the LaboratoriesLaboratories MedicalMedical records records OverOver the the counter counter medication medication sales sales sources. We are going to review notifiable RegistriesRegistries SurveysSurveys disease surveillance later in the presentation. .. populationpopulation-based-based .. providerprovider-based-based But some other sources of data that you may be familiar with include vital records, such as birth certificates, and death certificates. Environmental monitoring systems, animal health data, information provided from individuals, information from laboratories, medical records at outpatient healthcare facilities, as well as hospitals. Over the counter medication sales can be a source of data. Registries are sources of data, and finally surveys. Some examples of surveys are population-based surveys such as the National Health Interview Survey, and the National Health & Nutrition Examination Survey, or NHANES. And then there are also provider-based surveys. Some examples of these are the National Ambulatory Medical Care Survey, and also the National Hospital Discharge Survey, which looks at ICD-9 codes.
Slide 7: Types of Surveillance
Let’s turn now to talk about different types of PassivePassive surveillance, and there are three types I would ActiveActive like to discuss in this presentation. Passive SyndromicSyndromic surveillance, active surveillance, and also syndromic surveillance.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 8: Passive Surveillance
Passive surveillance is the most common form of Laboratories,Laboratories, physicians, physicians, or or others others regularly regularly report report casescases of of disease disease / / death death to to the the local local or or state state health health surveillance and occurs when laboratories, departmentdepartment .. CaseCase reports reports based based on on a a standard standard case case definition definition of of that that physicians, or other healthcare providers particularparticular disease disease .. DeathsDeaths reported reported on on standard standard certificate certificate regularly report cases or disease to the local health department. These reports are based on standard case definitions for a particular disease or condition. Passive surveillance means that the healthcare provider or laboratory initiates the forwarding of the data to the health department.
Slide 9: Active Surveillance
A second form of surveillance is active LocalLocal or or state state health health departments departments initiate initiate the the collectioncollection of of information information from from laboratories, laboratories, surveillance. This occurs when the collection of physicians,physicians, health health care care providers providers or or the the general general population.population. data from the lab, physician, or other healthcare .. AchievesAchieves more more complete complete and and accurate accurate reporting reporting .. MoreMore resource resource intensive intensive for for the the public public health health agency agency provider is initiated by the health department. ▪▪moneymoney ▪▪personnelpersonnel Active surveillance is often used during outbreak ▪▪timetime investigations or research studies. Active surveillance has an advantage over passive surveillance because it achieves more complete and accurate reporting. However, the draw-back is that it’s more resource intensive for the public health agency that is conducting the active surveillance. It costs more, it takes more personnel, and more time to do active surveillance.
Slide 10: Syndromic Surveillance
TheThe ongoing, ongoing, systematic systematic collection, collection, analysis, analysis, A third type of surveillance is syndromic interpretation,interpretation, and and application application of of real real--timetime indicatorsindicatorsforfor disease disease that that allow allow for for detection detection before before surveillance. It is defined as the ongoing, publicpublic health health authorities authorities would would otherwise otherwise identify identify them.them. systematic collection, analysis, interpretation,
CommonCommon surveillance surveillance syndromes syndromes and application of real-time indicators for .. GastrointestinalGastrointestinal .. InfluenzaInfluenza-like-like illness illness disease that allow for detection before public . Rash and Fever . Rash and Fever health authorities would otherwise identify them. Syndromic surveillance data are collected in real time, meaning that the data are automated so that they can be received daily, or even more frequently. The type of data collected is not actual disease, instead we are interested in specific indicators of disease. The definition of syndromic surveillance, you’ve probably noticed is similar in ways to the definition of surveillance in general. It’s on-going and systematic collection, there’s analysis and interpretation of data, however, the time component and type of data collected are different from passive, or even active, surveillance. Some common surveillance syndromes are: gastrointestinal illness,
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
influenza-like illness, or rash and fever syndrome.
Slide 11: Ideal Surveillance System
What are the key features of an ideal SimpleSimple TimelyTimely RepresentativeRepresentative surveillance system? We want the system to be FlexibleFlexible SensitiveSensitive simple, which means it’s easy to participate in StrongStrong predictive predictive value value AcceptableAcceptable and the daily operation of it is not too .. publicpublic .. healthhealth care care providers providers cumbersome. It also needs to be timely, data CostCost--effectiveeffective that’s not available when we need it, is not helpful for planning or response. It needs to be representative, which means that a surveillance system needs to collect data that’s representative of the population that we’re following. It needs to be flexible, which means at certain times, such as outbreak situations, you need to be able to ramp it up, but then in times when there are not a lot of cases you need to be able to scale back. It needs to be sensitive and have strong predictive value, which we’ll talk about in the next few slides. It certainly needs to be acceptable. Both the public and healthcare providers need to feel like what they’re doing makes sense, and that it’s not too intrusive. And finally, an ideal surveillance system needs to be cost effective.
Slide 12: Ideal Surveillance System
So in the next few slides we’re going to spend a SimpleSimple TimelyTimely RepresentativeRepresentative little bit more time talking about these two FlexibleFlexible SensitiveSensitive characteristics (Sensitive and Strong Predictive StrongStrong predictive predictive value value AcceptableAcceptable Value) of an ideal surveillance system. .. publicpublic .. healthhealth care care providers providers CostCost effective effective
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 13: Ideal Surveillance System – Sensitivity and Predictive Value
SensitivitySensitivity .. FewFew if if any any missed missed cases cases For an ideal surveillance system to be sensitive, .. IncreaseIncrease by by having having broad broad case case definitions definitions PositivePositive predictive predictive value value we want it to not miss many cases. We want to .. AlmostAlmost all all case case reports reports received received for for illnesses illnesses meet meet the the surveillancesurveillance case case definition definition have few, if any, missed cases of the disease .. IncreaseIncrease by by adopting adopting a a more more restrictive restrictive case case definition definition we’re trying to track. We increase the sensitivity of a surveillance system by having very broad Hopkins, R. 2005 Hopkins, R. 2005 case definitions, which means that we capture cases that may not actually be cases by only have a few characteristics that we’re looking for, for each disease. Clearly, the problem with that is there will be cases counted that might not actually be true cases of disease. But if you really are trying to catch every case out there, and not miss any then we have to have a sensitive surveillance system. The flip side of that is positive predictive value of a surveillance system. All case reports that we are receiving for a disease or illness meet the case definition; we can feel fairly certain that any cases we’re capturing in our system truly represent cases. We can increase the predictive value of a surveillance system by adopting a more restrictive case definition: individuals have to match more characteristics of a disease to be counted as a case. There is a balance, or a trade-off, between sensitivity and predictive value of a surveillance system.
Slide 12: Uses of Public Health Surveillance
Next we’re going to talk a little bit about the uses EstimateEstimate magnitude magnitude of of the the problem problem DetermineDetermine geographic geographic distribution distribution of of illness illness of public health surveillance. Public health PortrayPortray the the natural natural history history of of a a disease disease DetectDetect epidemics epidemics / / define define a a problem problem surveillance can be used to estimate the GenerateGenerate hypotheses, hypotheses, stimulate stimulate research research EvaluateEvaluate control control measures measures magnitude of a health problem; it can help us MonitorMonitor changes changes in in infectious infectious agents agents DetectDetect changes changes in in health health practices practices determine the geographic distribution of an FacilitateFacilitate planning planning illness. It helps to portray the natural history of a http://www.cdc.gov/osels/ph_surveillance/nndss/phs/overview.htm http://www.cdc.gov/osels/ph_surveillance/nndss/phs/overview.htm disease, is it on the rise, is it on the decline? It helps us detect epidemics, or define problems in the community. It can help us generate hypotheses, and stimulate research. It helps us evaluate our control measures. We can monitor changes in infectious agents, for examples whether certain bacteria are becoming more resistant to some of the antibiotics that are in use. Surveillance helps us detect changes in health practices; are more people getting screened in a community, or are less people, and what are the barriers? Finally, surveillance can help us facilitate planning.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 13: Uses of Public Health Surveillance
Let’s follow with a few examples. The first EstimateEstimate magnitude magnitude of of the the problem problem DetermineDetermine geographic geographic distribution distribution of of illness illness example is going to illustrate how surveillance PortrayPortray the the natural natural history history of of a a disease disease DetectDetect epidemics epidemics / / define define a a problem problem helps us estimate the magnitude of a problem, GenerateGenerate hypotheses, hypotheses, stimulate stimulate research research EvaluateEvaluate control control measures measures and also at the same time determine the MonitorMonitor changes changes in in infectious infectious agents agents DetectDetect changes changes in in health health practices practices geographic distribution of illness. FacilitateFacilitate planning planning
Slide 14: Incidence of Chlamydia
This data is looking at the incidence of chlamydia among women in the United States in the year 2009. It gives us incidence by state and shows us right away the magnitude of the problem, in the sense that chlamydia is very common. We have geographic distribution as well, by showing the http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5853a1.htm http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5853a1.htm states that are highlighted or shaded in dark blue clearly have, a higher incidence of chlamydia than other states.
Slide 15: Uses of Public Health Surveillance
The next example is the use of public health EstimateEstimate magnitude magnitude of of the the problem problem DetermineDetermine geographic geographic distribution distribution of of illness illness surveillance to detect epidemics. PortrayPortray the the natural natural history history of of a a disease disease DetectDetect epidemics epidemics / / define define a a problem problem GenerateGenerate hypotheses, hypotheses, stimulate stimulate research research EvaluateEvaluate control control measures measures MonitorMonitor changes changes in in infectious infectious agents agents DetectDetect changes changes in in health health practices practices FacilitateFacilitate planning planning
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
BOTULISM,BOTULISM, Foodborne Foodborne Outbreak Outbreak Slide 16: Botulism ReportedReported cases, cases, by by year, year, United United States, States, 1982 1982-2002-2002 This is data from the CDC from 2002, looking at botulism that was responsible for foodborne outbreaks over a 20-year period, from 1982 to 2002. There are definite peaks in the number of cases of botulism, and there are labels showing which ones were related to foodborne Source: CDC. Summary of notifiable diseases. 2002. Source: CDC. Summary of notifiable diseases. 2002. Data from the annual survey of State Epidemiologist and Directors of State Public Health Laboratories.. Data from the annual survey of State Epidemiologist and Directors of State Public Health Laboratories.. outbreaks.
Slide 17: Uses of Public Health Surveillance
Finally, the last example is how public health EstimateEstimate magnitude magnitude of of the the problem problem DetermineDetermine geographic geographic distribution distribution of of illness illness surveillance can help us evaluate our control PortrayPortray the the natural natural history history of of a a disease disease DetectDetect epidemics epidemics / / define define a a problem problem measures. GenerateGenerate hypotheses, hypotheses, stimulate stimulate research research EvaluateEvaluate control control measures measures MonitorMonitor changes changes in in infectious infectious agents agents DetectDetect changes changes in in health health practices practices FacilitateFacilitate planning planning
Slide 18: Cases of Varicella or Chicken Pox VaricellaVaricella(ChickenPox(ChickenPox).). Number Number of of reported reported cases cases ------Illinois,Illinois, Michigan, Michigan, Texas, Texas, and and West West Virginia*, Virginia*, 1993 1993----20092009 This figure is a line graph that is showing the number of cases of varicella or chicken pox in 4 states from 1993 to 2009. On the y-axis we have the number of cases in thousands of chicken pox. On the x-axis we have the period of time from 1993 to 2009. What you see overall is a steady www.cdc.gov/mmwr/preview/mmwrhtml/mm5853a1.htm www.cdc.gov/mmwr/preview/mmwrhtml/mm5853a1.htm decline in the number of cases of chicken pox, but this data also shows us that licensing of varicella vaccine in the mid-90s was followed by a steady decline in the number of cases of chicken pox. Then in 2006 a second dose of varicella vaccine was recommended, and you can see from 2006 to 2009 there was a decline in the number of cases.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 19: Notifiable Disease Surveillance
We are going to turn now to notifiable disease FoundationFoundation is is state state and and local local application application of of the the reportablereportable disease disease surveillance surveillance system system known known as as reporting. It has been said that no health NationalNational Notifiable Notifiable Disease Disease Surveillance Surveillance System System (NNDSS)(NNDSS) department can effectively prevent or control .. InfectiousInfectious reportable reportable diseases diseases .. NoninfectiousNoninfectious reportable reportable diseases diseases disease without knowledge of when, where, and ▪▪CancerCancer ▪▪ElevatedElevated blood blood lead lead levels levels under what conditions cases are occurring. ▪▪PesticidePesticide-related-related illness illness Public health agencies monitor diseases and conditions of importance by designating them as notifiable. The foundation of notifiable disease surveillance is the state and local application of the National Notifiable Disease Surveillance System. A list of nationally notifiable diseases is available at the Centers for Disease Control and Prevention website. You will find that most of the diseases are infectious in nature, but there are some that are non-infectious, and I’ve listed some of the examples here. Cancer, elevated blood lead levels, and pesticide-related illness are just some examples of conditions that are reportable, but are non-infectious.
Slide 20: National Notifiable Disease Surveillance System (NNDSS)
SystemSystem for for passing passing reports reports from from the the local local to to state state healthhealth departments, departments, and and then then on on to to CDC CDC The National Notifiable Disease Surveillance .. RoleRole of of the the Council Council of of State State and and Territorial Territorial Epidemiologists Epidemiologists (CSTE)(CSTE) System is a system for passing reports from local ListList of of disease disease and and laboratory laboratory findings findings of of public public healthhealth interest interest and state public health agencies through to the .. CaseCase definitions definitions for for their their surveillance surveillance DisseminationDissemination of of surveillance surveillance data data CDC. There is a role for the Council and State .. MorbidityMorbidity and and Mortality Mortality Weekly Weekly Report Report (MMWR) (MMWR) .. MMWRMMWR Annual Annual Summary Summary of of Notifiable Notifiable Diseases Diseases and Territorial Epidemiologists (CSTE) who work closely with the CDC in revising the list of nationally notifiable disease every year. The CDC keeps a list of disease and laboratory findings of public health interest, and also with support from the CSTE, maintains case definitions for their surveillance. The CDC also works to disseminate surveillance data back to healthcare providers. They do this through the Morbidity and Mortality Weekly Report (MMWR). They also publish an Annual summary of Notifiable Diseases.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 21: Case Definitions
This is an example of a case definition that you UniformUniform criteria criteria for for reporting reporting cases cases .. Clinical,Clinical, Laboratory, Laboratory, Epidemiologic Epidemiologic can find at the CDC website. This is the 2011 case definition for hepatitis A, which is a nationally notifiable disease. The case definition includes a clinical component, a laboratory component, and an epidemiologic component, http://www.cdc.gov/osels/ph_surveillance/nndss/casedef/hepatiti sacurrent.htmhttp://www.cdc.gov/osels/ph_surveillance/nndss/casedef/hepatiti sacurrent.htm (often used during outbreak investigations).
MMWRMMWR AnnualAnnual SummarySummary ofof Slide 22: MMWR Annual Summary of Notifiable NotifiableNotifiable DiseasesDiseases Diseases
The CDC disseminates surveillance data back to providers. More detailed information is published in the MMWR Annual Summary of Notifiable Diseases. In this publication, data for all reportable or notifiable diseases are
http://www.cdc.gov/mmwr/PDF/wk/mm5754.pdf http://www.cdc.gov/mmwr/PDF/wk/mm5754.pdf published, along with a brief summary of the year’s activity and information on recent case definitions. At the end of the report are summary tables and maps. This is an example of a map showing the rate of newly reported AIDS cases per 100,000 people in the United States in 2002. The information from the CDC is invaluable source for learning about and understanding the broad scope of disease surveillance around the country. It also allows healthcare professionals and public health officials to see what’s going on in their own state, as well as other states around them. Finally, the publication of these reports shows the collaborative nature of surveillance. Without the work of healthcare providers and local health departments these data would not be available.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 23: State Participation in NNDSS
State participation in the National Notifiable ReportingReporting by by states states to to the the CDC CDC is is voluntary voluntary ReportingReporting mandated mandated at at state state level level Disease Surveillance System is voluntary. There is .. statestate legislation legislation or or regulation regulation VariationVariation in in the the lists lists of of reportable reportable diseases diseases exists exists not a legal requirement that states have to betweenbetween states states participate in this system; however, all states choose to participate. Reporting of notifiable disease is mandated at the state level and the list of diseases varies by state. Reportable conditions are determined by laws and regulations of each state and jurisdiction. Some conditions deemed nationally notifiable might not be reportable in certain states or jurisdictions. It’s important as a healthcare provider to know what the list of diseases that are notifiable, are in the states that you’re practicing in.
Slide 24: Example of Physician Report – Hepatitis B
ResidentResident of of long long--termterm care care facility facility hospitalized hospitalized with with acuteacute hepatitis hepatitis B B The next few slides are going to highlight .. PhysicianPhysician reports reports case case to to local local health health department department (LHD) (LHD) ▪▪LHDLHDnursenurse remembers remembers several several other other cases cases of of acute acute examples of healthcare providers who did their hepatitishepatitis B B at at same same facility facility in in past past year year ▪▪UnsuspectedUnsuspected outbreak outbreak of of acute acute hepatitis hepatitis B B was was discovereddiscovered in in the the facility facility part in surveillance and reported a notifiable disease to their local health department. The first is an example of a physician who reported a case of hepatitis B to the local health department. This case of acute hepatitis B was in a resident of a long-term care facility, who was admitted to the hospital with hepatitis B. After the physician made the report for this one case, the health department nurse remembered that there were several other cases of acute hepatitis B that had occurred recently at the same long-term care facility. An investigation was begun, and an unsuspected outbreak was discovered at the long-term care facility.
Slide 25: Example of Physician Report – Hepatitis B
These cases ended up being part of a larger study that looked at the transmission of hepatitis B virus among people undergoing blood glucose monitoring in long-term care facilities
MMWR, March 11, 2005 / 54(09);220-223 MMWR, March 11, 2005 / 54(09);220-223
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 26: Example of Physician Report – Listeriosis
StillbornStillborn infant infant delivered delivered at at hospital hospital diagnosed diagnosed with with listeriosislisteriosis Another example is a health care provider who .. PhysicianPhysician reports reports case case to to LHD LHD ▪▪OutbreakOutbreak of of listeriosis listeriosiswaswas identified identified among among reported a case of listeriosis to their local health HispanicHispanic females females with with 12 12 cases cases identified identified over over 4 4 month month periodperiod 55 stillbirths stillbirths department. This was a pediatrician who 33 premature premature births births 22 infected infected newborns newborns attended a delivery of a stillborn infant. The ▪▪CaseCase-control-control study study identified identified common common source source of of exposure exposure physician reported this case to the local health department and because of this case report and further investigation, the health department discovered an outbreak of listeriosis, identified among Hispanic females with 12 cases identified over four months. There were five stillbirths associated with this outbreak, three premature births and two newborns who were infected with listeriosis. A case control study was performed to discover what the source of the exposure was for all of these cases.
Slide 27: Example of Physician Report – Listeriosis
Investigators found that the source of the outbreak of Listeriosis was associated with homemade Mexican style cheese or queso fresco.
MMWR, July 06, 2001 / 50(26);560-2 MMWR, July 06, 2001 / 50(26);560-2
Slide 28: Example of Physician Report – Listeriosis
This is one of the samples that was tested during this outbreak investigation. Again this outbreak was initially identified because a healthcare provider had reported the disease to the local health department. Used with permission from Robert E. Whitwam Used with permission from Robert E. Whitwam
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 29: Limitations of Surveillance
IncompleteIncomplete data data With all systems and programs there are OverwhelmingOverwhelming volumes volumes of of data data from from a a variety variety of of sourcessources make make management management complex complex limitations. Some of the limitations of UnevenUneven application application of of information information technology technology .. PaperPaper versus versus electronic electronic reporting reporting surveillance systems are listed here. We’re TimelinessTimeliness .. ReportingReporting time time requirement requirement always dealing with incomplete data. There's .. ReportingReporting burden burden CompletenessCompleteness overwhelming volumes of data sometimes .. UnreportedUnreported cases cases .. IncompleteIncomplete reports reports coming in from a variety of sources which makes the organization and management of all that data complicated. With the continuing advancement of information technology, there's uneven application of surveillance. Some jurisdictions still have paper-based reporting, where case reports are completed on paper and mailed in or faxed. There is a transition over to electronic reporting or internet-based reporting. So we're in a period of transition with an uneven application of the information technology; two systems trying to merge together. Timeliness is an issue, how fast can we get the data that we need? Completeness of the data that's being reported is another issue. Sometimes cases aren’t reported at all and sometimes the cases that are reported have data that's missing. Trying to improve all of these areas are challenges that public health agencies face on a daily basis.
CDC’sCDC’s Burden Burden of of Illness Illness Pyramid: Pyramid: Underascertainment Underascertainmentofof Slide 30: Burden of Illness Pyramid FoodborneFoodborne Illness Illness in in Notifiable Notifiable Diseases Diseases Surveillance Surveillance The burden of illness pyramid depicted here is a model for understanding foodborne disease reporting. This illustrates steps that must occur for an episode of illness in the population to be registered in a surveillance database. Starting
Source: Adapted from Centers for Disease Control and Prevention, “FoodNet Surveillance - Burden of Illness from the bottom of the pyramid, the areas in Pyramid.”Source: Adapted http://www.cdc.gov/foodnet/surveillance_pages/burden_pyramid.htm from Centers for Disease Control and Prevention, “FoodNet Surveillance. Accessed - OctoberBurden of 3, Illness2011. Pyramid.” http://www.cdc.gov/foodnet/surveillance_pages/burden_pyramid.htm. Accessed October 3, 2011. yellow, shows that some members of the general population can be exposed to an organism, but not all of them will become ill. The next line of the pyramid represents people who do become ill. In the pink portion of the pyramid, a percentage of people who become ill will seek care, and of those that do seek care, in a proportion of them a specimen will be obtained. Then in the purple portion of the pyramid some of those lab tests will be submitted for the organism of interest and the laboratory will confirm a case. Only a small proportion of those will be reported to the health department, which represents that very small section at the top of the pyramid in green. You can get data on foodborne illnesses in other ways; surveillance is really just the tip of the iceberg in terms of diseases that are reported to the health department. There are surveys that are done at the laboratory level to look at what lab tests are positive. Active surveillance can involve a physician survey targeting that pink portion of the pyramid, where you can actually ask healthcare providers if they've seen a
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certain number of people with a constellation of signs and symptoms. And finally at the bottom of the pyramid you can perform population surveys, were you interview a whole group of people to find out about common exposures and also what group of people became ill even if they didn’t seek care. So the surveillance data, the Notifiable Disease Surveillance really is the top of the pyramid or the tip of iceberg. And that’s the take home point when you're reviewing surveillance data, to realize that the number of cases reported for any specific condition is always going to be an underestimation of the actual number of cases out there.
Slide 31: Limitations of Surveillance – Shigella
This is a similar example of the pyramid. This 100100 persons persons infected infected with with shigella shigella 7676 symptomatic symptomatic was from a 1977 article by Rosenberg, which 2828 consulted consulted a a healthcare healthcare provider provider 99 submitted submitted stool stool cultures cultures talked about cases of shigella. He found in his 77 had had positive positive results results 66 reported reported to to the the local local health health department department study that for every 100 people infected with 55 reported reported nationally nationally to to CDC CDC shigella about 3/4 of them or 76 would be symptomatic. 28 would go to a healthcare Rosenberg et al, 1977 Rosenberg et al, 1977 provider for evaluation, only nine of those 28 would have stool cultures submitted for testing, seven would have positive results, six of the cases of confirmed shigella would be reported to the local health department, and only five would actually be reported to the CDC. So out of 100 people infected with shigella, it's estimated that only five are reported to the CDC.
Slide 32: Reasons for Failure to Report
In a 2002 study by Doyle et. al, the authors 1.1. LackLack of of awareness awareness of of legal legal requirement requirement 2.2. LackLack if if knowledge knowledge of of which which conditions conditions are are reportablereportable looked at some of the reasons why healthcare 3.3. LackLack of of knowledge knowledge of of how how or or to to whom whom to to report report 4.4. AssumptionAssumption that that someone someone else else will will report report the the case case providers fail to report. Oftentimes it's a lack of 5.5. IntentionalIntentional failure failure to to report report to to protect protect patient patient privacyprivacy awareness or knowledge of what conditions 6.6. InsufficientInsufficient reward reward for for reporting reporting 7.7. InsufficientInsufficient penalty penalty for for not not reporting reporting need to be reported. A lot of providers don't know that it's a legal requirement for them to Doyle et al, 2002 Doyle et al, 2002 report. They may not understand the process if they have a disease they need to report: who do they report it to? Oftentimes there's an assumption that someone else will take care of it, it’s someone else's job to report. Occasionally providers don't report on purpose or intentionally because they want to protect patient privacy. Finally it's been found that insufficient reward or insufficient penalty are reasons why providers wouldn’t report.
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Slide 33: Limitations of Syndromic Surveillance
I wanted to mention limitations of syndromic CostlyCostly surveillance as well. We’ve mentiond that StaffStaff expertise expertise required required syndromic surveillance certainly has advantages FormalFormal evaluations evaluations of of syndromic syndromic surveillance surveillance systemssystems are are incomplete incomplete over passive surveillance because it's real time data, it’s automated, it's coming in quickly. But syndromic surveillance systems are costly and they require resources to bring together all of the different syndromic data from hospitals, ambulance transport, poison control centers, and even school absenteeism as part of the syndromic surveillance system. They require significant staff expertise and dedicated time. We talked early on about an ideal surveillance system would be simple, but certainly syndromic surveillance requires staff expertise. Finally formal evaluations of existing syndromic surveillance systems are incomplete, so the data still out on how well these work in terms of how cost effective they are. It’s important to keep in mind that syndromic surveillance systems are not meant to replace regular surveillance systems but rather to enhance the data that we are already getting from a passive surveillance system.
Slide 34: Limitations of Syndromic Surveillance
Other limitations of syndromic surveillance are InadequateInadequate specificity specificity = = false false alarms alarms .. SoftwareSoftware recognizes recognizes key key words words false alarms and failure to detect outbreaks. .. UsesUses resources resources in in investigation investigation
InadequateInadequate sensitivity sensitivity = = failure failure to to detect detect outbreaks outbreaks False alarms can occur because of non-specific oror bioterrorism bioterrorism events events .. OutbreakOutbreak is is too too small small case definitions. Syndromic surveillance systems .. PopulationPopulation disperses disperses after after exposure, exposure, cluster cluster not not evident evident are run off software that recognizes keywords as part of the syndrome’s case definition (e.g. fever and rash). This results in many more cases being picked up that aren’t representative; these are considered false alarms. There can also be inadequate sensitivity meaning syndromic surveillance is not detecting all outbreaks or bioterrorism events. This can occur if the outbreak is too small to raise a red flag that the number of cases has gone beyond a set threshold. Also, if this syndromic surveillance data are coming from a number of different healthcare facilities across a state or region, an outbreak can be missed. If a group of people is exposed in one location but disperses after the event, the cluster may not be evident via syndromic surveillance.
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Slide 35: Summary
In summary, surveillance data has many practical SurveillanceSurveillance data data has has many many practical practical uses uses NotifiableNotifiable disease disease surveillance surveillance is is fundamental fundamental to to uses and is the crux of the public health core preventionprevention and and control control efforts efforts ListList of of notifiable notifiable diseases diseases varies varies by by state state function assessment. Notifiable disease SignificantSignificant improvements improvements are are being being made made in in advancingadvancing surveillance surveillance and and reporting reporting surveillance is fundamental to prevention and control efforts in public health. Regardless of where you practice the list of notifiable diseases is going to vary by state. Finally we've talked about limitations in surveillance, but significant improvements are being made in advancing surveillance and reporting, so stay tuned and make sure you understand your role in this vital public health function.
Center for Public Health Continuing Education University at Albany School of Public Health
Department of Community & Family Medicine Duke University School of Medicine
Mike Barry, CAE Denise Koo, MD, MPH Lorrie Basnight, MD Suzanne Lazorick, MD, MPH Nancy Bennett, MD, MS Rika Maeshiro, MD, MPH Ruth Gaare Bernheim, JD, MPH Dan Mareck, MD Amber Berrian, MPH Steve McCurdy, MD, MPH James Cawley, MPH, PA-C Susan M. Meyer, PhD Jack Dillenberg, DDS, MPH Sallie Rixey, MD, MEd Kristine Gebbie, RN, DrPH Nawraz Shawir, MBBS Asim Jani, MD, MPH, FACP
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Module 7: Outbreak Investigation & Disease Control – Public Health Surveillance TRANSCRIPT
Sharon Hull, MD, MPH President
Allison L. Lewis Executive Director
O. Kent Nordvig, MEd Project Representative
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