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0:26
Hello, I'm Ralph Cordell, an epidemiologist here at the Center for Disease Control in Atlanta. I've been asked to present this introduction to public health surveillance as part of our Public Health 101 series. You may find it hard to believe, but I've worked in public health for almost 40 years. I started out as a microbiologist with the Illinois Department of Public Health virus lab, then went on and got my Ph.D. in epidemiology and worked with the Cook County Department of Public Health
0:55
as an epidemiologist in their communicable disease program. I came to CDC in 1992, worked with infectious diseases in out-of-home child care settings. I did some work with health care quality and health care associated infections.
1:14
I taught applied epidemiology at the University of Illinois School of Public Health. I think one of the things I've learned over the years is the importance of surveillance, that public health surveillance is one of the most important aspects of public health system. Surveillance data drives our decisions, directs our actions. Like the proverbial dog in the night, it informs us of potential threats to the health of those we serve. In the next hour, I'll discuss some
1:47
of the basics of surveillance- its role and use in public health. I'll review the legal basis for surveillance, discuss some of the types of surveillance, attributes of surveillance, and the processes involved in conducting surveillance. Finally, we'll apply what we've learned in some cases where surveillance was used to address a public health problem. Throughout this presentation, I'll try to bring examples based on some of my experiences. I'm sure that many of you have had similar experiences
2:17
or soon will, and I would encourage you to try to fit them into the models that we present here. I'm sure that many of you have had similar experiences or soon will and I would encourage you to try to fit them into models that we present here. The day-to-day routine of the local health department can be stressful and sometimes chaotic, and it helps to be able to find some structure and purpose to the activity. At the end of this tape if I've done my job and you stayed awake, you should be
2:46
able to define, or at least explain, what's meant by public health surveillance, at least to the point where you know the key characteristics and how surveillance differs from data collection for research purposes. You should be able to describe the goal of public health surveillance, should be able to describe the uses of public health surveillance systems. This use generally drives the structure of the system, what information is collected,
3:09
who it's collected from, and how and when it's analyzed. We will also discuss the legal basis for public health surveillance in the United States. Now, this may sound boring, but a solid understanding of the legal basis for collecting the information can be helpful when dealing with attorneys at the local level. We'll discuss active and passive public health surveillance and identify sources of data commonly used for public health surveillance. Lastly, we'll describe the process of public health
3:38
surveillance itself. Few things in my career been more gratifying to identify a public health problem through surveillance, to find that some sneaky little bug was infecting my people, making them sick, putting them in the hospital, and even killing some of them. And nobody would have known about it if not for the efforts of those involved in our surveillance system. And then to track it down and snuff it out makes everything worthwhile.
4:02
We'll start with a discussion of the public health approach to problem solving. Public health problems are diverse and can include infectious diseases, chronic diseases, emergencies, injuries, environmental health problems, and other health threats. Regardless of the topic, we take the same approach to public health problems by following four general steps. We start by asking, what is the problem? Or even, is there a problem? In public health, we identify the problem
4:31
by using surveillance systems to monitor health events and behaviors occurring among the population. After we've identified the problem, the next question is, what's the cause of the problem? For example, are there factors that might make certain populations more susceptible to disease, such as something in the environment or certain behaviors that people are practicing to put them at risk? This is where epidemiology comes in. Once we've identified potential risk factors related
5:01
to the problem, we ask what intervention works to address the problem? We generally look at what has worked in the past in addressing the same or similar problems and if a proposed intervention makes sense with our affected population. It may be worthwhile to look at what did not work and why. The last step, we ask, how can we implement the intervention? Given the resources we have and what we know about the affected population, will this work? As we go through this course, you'll
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see different examples of this public health approach at work. This diagram includes some of the core disciplines that represent the foundation for the public health approach. These include public health surveillance, which we use to monitor the public health situation. We will learn more about surveillance during the today's discussions. Epidemiology helps us to understand where diseases originate, how or why they move through populations, and how we can prevent them.
5:58
Public health laboratories support public health by performing tests to confirm disease diagnosis. Laboratories also support public health efforts through research and training. They play a key role in surveillance and investigations. As we continue to move from the use of paper documents to electronic health records, public health informatics continues to increase in importance. Informatics deal with methods for collecting, compiling, and preserving health education, and it
6:27
enables us to use electronic data effectively when addressing a public health situation. Prevention effectiveness is closely linked to public health policy. Its studies provide important economic information for decision makers to help them choose the best options available. So essentially, it tells us- is the juice worth the squeeze? Together, these five core sciences can help us protect and promote public health by giving practitioners the answers they need in order to do their jobs.
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Public health is better able to respond to the situation by using contributions from each of these sciences. No one science alone is able to do the job by itself.
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Moving on to the next topic- When many people hear the word surveillance, they often think of James Bond, or Hawaii Five-0, or Big Brother types of spying. I suppose that could apply here, except for tracking disease patterns and health status, not individuals.
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The term surveillance comes from a French word meaning "to watch over." Public health surveillance has been defined as the ongoing systematic collection, analysis, and interpretation of health related data essential to planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination of these data to those responsible for prevention and control. While collecting data for research purposes and collecting data for surveillance may be similar,
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there are some fundamental differences. I found it useful to keep this definition in mind and to periodically apply it to surveillance systems I've been working with. There are some key terms that are especially important to keep in mind. Surveillance is, first of all, systematic. It's useful to think of systematic in terms of standardized. It's asked, just how standardized is your surveillance system? Is everyone using the same methods, the definitions, or have they changed over time?
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It's good to look at what factors might influence the completeness, equality, and timeliness of your data reporting. The next term is ongoing. The ongoing nature of surveillance data collection is one attribute that distinguishes it from research data collections. Data collection for research purposes are tied to the duration of the study, while surveillance is ongoing. Although things like definitions, instruments, and data fields may change over time, the systems generally keep chugging on.
9:06
It also does not mean continuous. Some systems, such as influenza and arbovirus surveillance systems are seasonal, how every year the leaves turn and public health departments start their flu surveillance. In the summer, they conduct arbovirus surveillance. The next term is collection. What, how, and from whom a data collection are all factors that need to be considered. Now, we'll discuss these more later in the presentation. Analysis is one area where surveillance and research
9:40
definitely differ. Data collection for research purposes are generally analyzed at the end of the study, after all the data's been collected. The analysis of surveillance data is generally an ongoing activity. I'll talk more about the rest of these key words, such as interpretation, dissemination, health-related data, and linkage to public health practice later on in this presentation. OK, let's move on to why we do surveillance and what we're trying to accomplish.
10:12
According to the slide, the goal of public health surveillance is to provide information that could be used for action and guidance. We'll look at some examples of surveillance leading to action later in this presentation, but it's important to keep in mind that that action is an important outcome of any surveillance program. You need to understand what you're going to do with the data that you have. OK, let's do a quick knowledge check. Which of the four choices is most correct- A, B, C, or D?
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If you picked C, you're correct. Public health surveillance is the on going systematic collection, analysis, and interpretation of health-related data. I have another knowledge check question. What's the goal the public health surveillance? The correct answer here is B, to provide information to be used for public health action. OK, moving on. We'll talk a bit about the role and uses of public health surveillance. Now that we've defined surveillance,
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let's discuss its role and uses in public health. Here are some specific ways public health services can be used. You may want to think about where some of the surveillance systems you're aware of fit into this scheme. Now this is being recorded in September 2014. Ebola virus infections are rampant and [? stomping ?] through much of West Africa. We have an enterovirus of 64 outbreaks going in a good part of this country. This first bullet represents one of the major activities
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public health officials are using to slow the spread of both diseases. Contact tracing and treatment are important parts of many sexually transmitted disease programs in this country, as is prophylaxis in the forms of antimicrobrials or immunoglobulin for folks exposed to some forms of bacterial meningitis or hepatitis A, respectively. The second and third bullets represent the alarm function of surveillance, although behavior changes may certainly be for the good.
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The magnitude and scope help identify populations at high risk. It targets specific groups for intervention. Surveillance data has also helped us to identify the spread of emergent infections like West Nile and to monitor increased resistance of antimicrobrials. We also use surveillance data to assess the effectiveness of programs, and control measures, as well as to develop hypothesis and stimulate research. Here are a few headlines from the past. Think about the surveillance uses
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we listed in the previous slide, and apply those to these headlines. How do we know that an epidemic is occurring? How do we know that the percentage of New Yorker smoking is decreasing? Are their obesity rates increasing or holding steady? Public health surveillance provides you answers to questions such as these, as well as many others. OK, this is part of the article on the number of rare E. Coli cases in the US rising last year. Notice that these results came from the National Monitoring
13:26
System for Foodborne Illness. Think about- going back to the previous slide, which surveillance uses can you link to this article? It's a knowledge check. Do we measure trends of a particular disease? Do we use it to estimate the magnitude of the problem? Do we use it to monitor changes in infection and environmental agents? Or do we use it to assess the effectiveness of programs and control measures? You can see that, essentially, it's all of the above. Now we know what surveillance is.
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We learned a little bit about its role and purpose. We'll move on to the legal basis and discuss just what gives health officials the authority, and even the obligation, to collect information about diseases. I remember asking this very question myself the first time I sat in an STD clinic and interviewed people about their sex histories. So it's important to keep this thing in mind and understand just why we're doing this. The 12th article of the Bill of Rights in the US Constitution
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states that the powers not delegated to the United States by the Constitution nor prohibited by it to the states are reserved to the states, respectively, or to the people. This has been interpreted as meaning that the legal authority for public health, including surveillance, resides with the states. However, the federal government is charged with promoting the general welfare of the people. It does have authority over interstate commerce. So putting these together, the CDC
15:00
can respond when a disease situation has interstate implications because of the commerce clause or when it impacts the general welfare of the nation. Otherwise CDC, typically, must be invited by a state to become involved in an investigation or to conduct surveillance within state boundaries. State-based notifiable disease reporting systems, also called reportable disease systems, are mandated by legislators through state law in some states.
15:32
In others, the legislatures gives the State Health Officer the authority to mandate reporting of specific diseases or conditions. These specify not only the list of diseases to report but also who must report, how to report, and when. Most commonly, physicians, laboratories, hospitals, clinics, and in some instances, school nurses and educators are required to report cases to the local health department. The local health department is usually responsible for the case investigations
16:04
and any resulting action. After a local health department receives a report, it verifies that it meets the case definition. They then send a report on to the state health department. Now, the state health department may assist the local health department in following up in investigations and control activities, especially if the problem's crossed jurisdictional lines. OK, another knowledge check. Which of the below serves as a legal basis for public health surveillance?
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The answer to this, of course, is number C, the US constitution.
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The next question- the CDC must be invited by a state before conducting public health surveillance. Is this true or false? This is sort of tricky, but the answer is true. Now we'll move on to a discussion of the various types of surveillance and some of the attributes of surveillance systems. We often divide surveillance into two categories- passive and active, depending on the amount of resources and effort put into it by the agency collecting the information.
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Most routine notifiable disease surveillance is considered passive. In passive surveillance, the physician, laboratory, or other health care provider, i.e. the reporter, takes the initiative in cementing the report by following a list of reportable diseases in that state. The state health department or health agency waits for reports to be submitted by others. This is the most common type of surveillance. It is simple and inexpensive, but it's also limited by the variability of quality
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and completeness of reporting. Active surveillance systems involve regular outreach to potential reporters to stimulate the reporting of specific diseases or injuries. Active systems involve regular outreach to potential reporters or to stimulate the reporting of specific diseases or injuries. Active surveillance is oftentimes used to validate the [? representiveness ?] of passive reporting, can be used to ensure more complete reporting conditions,
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or it can be used in conjunction with specific epidemiologic investigations. Active systems are often used for brief periods for discreet purposes, such as during outbreak investigations, or special time-limited events, or for diseases of special interest, such as SARS. The truth is that there is a gradient here. An even more active system might involve assigning staff to periodically visit reporting sources and review emergency room laboratory or other records for possible cases.
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Another type of surveillance is sentinel surveillance. A few reporting sources are selected to serve as sentinels. These may be clinicians' offices, laboratories, or other components of the health care system. They are asked to collect information and sometimes clinical specimens, such as throat swabs from patients meeting established criteria, or to conduct additional testing and screening, essentially, to go beyond the norm and to periodically report their reports.
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When I first started in public health, I was involved in a sentinel system for arboviruses where we used chickens. Arbovirus has a chicken, mosquito life cycle. We put chickens out in the woods, and every week, we'd go out and collect blood from the chickens to determine whether or not they'd been infected. So we can do this from sources other than just- this can involve more than health records. You can also look for activities in other types of systems.
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Another sentinel system, at one time cotton pledgets were put in sewers and periodically sampled and tested for enterobacteria to look at the presence of various enteric pathogens in communities, as well. The usefulness of syndromic surveillance became apparent after the outbreak of cryptosporidiosis in Milwaukee back in 1992 and the increased awareness of the threat of bioterrorism in 2001. Syndromic surveillances focuses on the signs and symptoms
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of an illness rather than on physician-diagnosed or laboratory-confirmed illnesses. The case definition for syndrome is less specific than that for disease. Therefore, follow up is always necessary to verify if an outbreak is actually occurring. Recent syndromic surveillance is an alarm system for bioterrorism events. An advantage to this method is that reporting does not need to wait for a diagnosis to be made. This can add time and delay the reporting process.
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Because of this time saving aspect of syndromic surveillance, it's been used as a method for early detection to improve situational awareness, especially in the context of bioterrorism. The term syndromic surveillance has also been loosely applied to the surveillance of school and work absenteeism, calls to 911, and the over-the-counter medications where, for example, a sharp increase in sales of antidiarrheal medications in the Milwaukee area served as an early indication of the outbreak
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of cryptosporidiosis.
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There are several key attributes that should be considered when setting up or evaluating a surveillance system. It is as important to understand the attributes of your surveillance system as it is to understand the attributes of your vehicle or your home. You need to understand what it can do, what it can't do. The first five are shown in this slide. By usefulness, we mean, is the system accomplish its objectives to the extent that we want? Data quality examines how reliable
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the data are that we're collecting to our surveillance system. How complete and accurate are the data fields in reports received by the system? Is there something we can do to improve quality? Do our reporting services need training? Can they reasonably provide the information requested from them? The next attribute is timeliness. How quickly are reports received? For some conditions, this is critical to prevent further illness, while in others, it may be less important.
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Flexibility looks at how quickly the system can adapt to changes. Simplicity considers whether this system is easy to operate. I set up the first computerized surveillance system for the Cook County Health Department. The first iteration included fields for almost all of the information we collected during the course of our investigations. Within a week, we were so far behind in data entry, that we scrapped the whole system and started again.
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The new system had only six data fields for each report. This system worked fine and was still in place when I left several years later. So simplicity is an important attribute to consider. The next attribute is stability. By stability, we mean, does a system work well? Does it break down very often? It's important to look at the sources of instability and how you might be able to improve the system. Things like staff turnover in key reporting sources
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can cause problems as much as crashes in the computer system. Sensitivity is another attribute. Sensitivity considers how well the system captures the intended cases. Does it capture only 10% of the cases, or does it capture 80%? If you have a system that only captures 10% but 80% is needed might not be effective enough for the condition or situation that you're looking at. Closer related to sensitivity is predictive value positive. With this we mean, how many of the reported cases
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are true cases that meet the criteria for what we're calling a case? That is, how many reported cases actually meet the case definition? Representativeness looks at how well the reports in the system represent the population under consideration. Does it identify events only among certain groups, or does it accurately capture events across the whole target population? Sexually transmitted disease surveillance systems are notorious for not representing the entire population.
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The final attribute is acceptability. How willing are the system users to actively participate in the surveillance efforts and to report their data? In the early days of the epidemic, name reporting of AIDS cases and HIV positivity was a real issue until people became comfortable with the system. Under real world conditions, we may need to balance some of the attributes of surveillance systems in order to accomplish the objectives. For example, sensitivity and predictive value positive
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typically have an inverse association. The more sensitive the system, the lower the predictive value positive. Therefore, one might decide whether you'd rather have a more sensitive system or a higher predictive value positive in order to accomplish your goal. This may vary from system to system. And here we have another knowledge check. The New York State Department of Health contacts the health care providers in District A every Friday to obtain the number of patients examined with influenza.
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What type of surveillance is this? The correct answer is B. Active. What if they were to send a notice to their providers at the start of the flu season reminding them to report? Then what would that system be? What if they were to send staff to a sample of emergency rooms to review records? Would that change the answer as well? A lot of decisions have to be made when you decide to place an illness or injury under public health surveillance. Public health surveillance process.
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A lot of decisions have to be made when you decide to put an illness or injury under public health surveillance, many of these deal with the process itself. And when using data from existing systems, it's good to keep in mind some of these same points to better understand the usefulness of what's going on with your system. We'll discuss each one of these steps in the process. At least five steps in the surveillance process need to be considered when setting up a surveillance system.
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These include data collection, analysis, interpretation, dissemination, and follow-up action. Let's start by looking at data collection. For collecting data, you must decide what the overarching goal of the system is and what the specific objectives might be in order to meet that goal. Possible questions to ask might include- What are we going to monitor? Just what data will be collected? What are our definitions and data fields? Why are we collecting this data?
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Why are we collecting these specific pieces of information? How are we going to use each one? And will the total of the system give us what we need? We also may want to ask, who will collect the data, and how will it be collected? What's the target population? Where do we implement the system? Will it be done in certain communities, type settings? Will the system be active or passive? How will the data be transmitted to the people that are actually performing the analysis? Will this by paper?
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Will it be by mail? Will it be electronically? What are the time factors involved? How are we going to put this system together to give us what we need to know? Surveillance relies on a variety of public data sources to monitor different conditions and situations. You might already be familiar with some of the data sources listed on the slide. Think about some others. These might include administrative data systems, such as billing records; laboratory surveillance, such as PulseNet.
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There may be environmental, vector, or animal surveillance. I talked about the sentinel chickens. We also were involved with mosquito trapping looking for West Nile viruses. Are there other systems as well, like pharmacies? Looking at laws and policies, as well as 911 calls. Moving on to the National Notifiable Disease Surveillances System. This is a collaboration between CDS and the Council of State and Territorial Epidemiologists, or CSTE. Many of the diseases on the state list
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are also nationally notifiable, but the reporting by state is voluntary. Now, each state determines which diseases and conditions are reportable within their jurisdiction. They also decide which ones from the list of national notifiable diseases or conditions they will report for their state. CSTE and CDC collaborate closely in developing this national list. It's revised yearly, and therefore varies somewhat from year to year, as well as from place to place.
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States typically fully cooperate with national disease reporting because CDC publishes the provisional data weekly in Morbidity and Mortality Weekly Report or MMRW, and the final data is published annually in the MMRW annual summary of notifiable diseases. MMRW displays the data in complex tables and maps such as the one displayed on the slide. This allows each state to know how their population's health compares with other states. This is the form from the Georgia Department of Public health.
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This is a Georgia notifiable disease form. What do you notice about this form? Now, I know that there are least four items. Most of these conditions are infectious. These are diseases that are passed from person to person or from animal or insect to people. Also, Georgia has four different reporting frames- immediately, seven days, one month, and six months. You may ask, who is required to report? This is in the top block. It includes physicians, laboratories, and other health care providers.
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The fourth and final item you might have noticed is that the form states that any cluster of illnesses is to be reported. The Georgia State Health Department then determines if that cluster is unusual. Health departments want to know about disease clusters. For example, before 1999, West Nile virus had not occurred in the US. Therefore in 1998, West Nile virus was not on Georgia's list. Health departments have been able to capture new or reemerging infectious diseases
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when clusters were reported. This was the case with West Nile virus. From an international perspective, the World Health Organization, or WHO, is the UN agency that coordinates international health activities, helps governments improve health services. International reportable conditions include smallpox, polio-- wild type polio infections-- human influenza caused by new subtypes, and severe acute respiratory syndrome, or SARS. OK. We have another knowledge check.
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State-based notifiable reporting requirements are set at the national level and are then reported at the international level. Is this true or false? The answer is false. OK, let's move on to the data analysis step. Some of the things you may want to ask here are who will analyze data, what methodology will they use? In some cases a simple graphic presentation may be adequate, while others may require more complex stratified analysis with calculation determination of confidence intervals.
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Last, how often will the data be analyzed? This can be done daily or be looked at weekly, monthly, or some other time frame. This is important. This is determined in part by the use of your surveillance system. If you're looking for outbreaks and emergencies it doesn't do any good to analyze your data once a month. Let's look at some examples. OK, this graph demonstrates an example of data analysis by week for the West Nile virus infection in New York State and New York City in 1999.
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This is when it was first introduced into the United States. This is the type of presentation that's useful for looking at these types of outbreaks. For other outbreaks you might want to adjust the y-axis to days or hours and the groups might represent classrooms or flares of [INAUDIBLE] or even person related variables. This graph shows us both the when and the where. Take a minute to look at it. What does it show you? First of all, we can see that the hospitalizations peaked
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on August 22 to 28. Keep in mind this is hospitalizations and not date of onset. The numbers held steady for the next two weeks and then began to decline in New York City, but they remained steady in New York state, as indicated by the striped blocks. However, the majority of cases overall occurred in New York City, as indicated by the solid blocks. This map is an example of laboratory confirmed West Nile cases among humans for August and September of 1999. Each red dot represents a human case.
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Where patterns can you see in this chart? Cases are scattered throughout the area, although there appears to be a cluster in the north Queens area, as indicated by the arrow. This suggests that there was a serial survey done in that area that may account for the cluster. Now, I don't know that's the case, but again, it's important to understand your surveillance system. And my ignorance and innocence can serve as this example of why it's
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important to understand what's going with your surveillance, how you collect your data, and what's behind it. Here's an example of data analysis by person. This table displays the demographics for persons hospitalized for West Nile virus and the population rates of infection over a selected period of time. What patterns do you notice in these rates? OK, well first of all, you see that the greatest number of cases appears to be in older folks, people 70 to 79 and those over 80.
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Now, in this case it might suggest that mosquitoes find it easier to bite slow moving seniors, but that's not necessarily the situation here. West Nile virus infections tend to be more severe in older people than in younger folks, and since we're looking at hospitalized data it's likely that this is reflecting sort of this increased severity in the older age group. If we look at gender, we'll find that the rates here in men and women are similar, although they appear to be
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a little bit higher in men. Now, this may, again, be just part of the reporting system or it may indicate that men are at higher risk. They may have more outdoor activities, be more exposed to mosquitoes than women. Moving onto the next slide here, interpreting data. This is closely linked with data analysis. By identifying the person, place, and time, you can determine how and why the health event occurred. Suppose that your analysis is identifies an apparent increase
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in reported cases in a disease under surveillance.
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You may want to ask, what can account for that apparent increase? Some reasons might be that there is an increase in access to health care. There may have been a change in reporting procedures or surveillance systems. There may be a changing case definition. It may be that more laboratories have [? begun ?] to test for the presence. It may be that there is more awareness of the condition than there was before. Oftentimes, we see after there's been an outbreak of a particular condition
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that we'll get increased reporting of this for a considerable period of time afterwards simply because providers are more aware of it and it's higher on the index of suspicion. OK, going on to a knowledge check here. In data interpretation, by identifying the blank, blank, and blank you can more easily determine how and why a health event occurred. What's the answer to this one? The answer is the old epi triad person, place, and time. That's number C. Another step in the [? process here ?]
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is data dissemination. Data dissemination basically tell how we're going to distribute our information to those who have a need to know. These can be done through health agency newsletters, bulletins, or alerts, you may have annual surveillance summaries or reports, they can be disseminated through medical epidemiologic journal articles, or there may be periodic press releases and now we have social media could also be used as a way to get information out to people.
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Some of the people that we may want to get information out to include public health practitioners, clinicians or other health care providers, those involved in making policies and other decision makers, community organizations, or the general public. A knowledge check. Which is the below is not a good source of data used for public health surveillance? And the answer in most cases would, of course, be C, newspaper articles. Now, one may be able to use newspaper reports if you were
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looking at police logs or something like that for a surveillance system, but for most public health purposes newspaper information would not be a good source of information. The last step to surveillance is a link to action. This is the final and required step to any sort of surveillance process, because without action the data serves no real purpose. OK, this graph shows the numbers of pertussis or whooping cough cases in the United States from 1922 through 2000.
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Looking at the big graph on the bottom here, what do you see? Well, you see here that it looks like data that you had a high number of cases up until the 1950s and it started to drop off as vaccines came into use. And then it plateaued out in the 1980s. But if you look, there appears to be something going on here from about 1980 to 2000 and this is shown in the small graph here in the upper right. You can see there were periods that the number of cases started to pick back up.
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We looked at this and found that a number of these cases involved adults or children who were exposed through adults. This served as the basis for a change in our recommendations regarding pertussis immunizations. Now we've expanded this to include adults. We now say that adults should receive a booster vaccination in order to protect them, keep them from spreading disease to young children. OK, last knowledge check here. Which of the below is not a part of the public health
41:08
surveillance process? A, B, C, or D. And the answer is B, data storage. Finally, let's take a look at some of the steps in surveillance-based action. Public health surveillance-based action includes these five steps-- describing the burden or the potential for disease; monitoring trends or patterns in disease; looking at risk factors and agents; detecting sudden changes in disease occurrence and distribution; providing data for programs, policies,
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and priorities; and evaluating prevention and control efforts. In the words of Bill Fahy, former CDC director, and a person who played a substantial role in the global smallpox eradication process, "The reason for collecting, analyzing, and disseminating information on a disease is to control that disease. Collection and analysis should not be allowed to consume resources if action does not follow." Hopefully during this session you've learned to define public health surveillance;
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you're able to describe the goal of public health surveillance; understand the uses of public health surveillance systems; recognize the legal basis for surveillance in the United States; compare active and passive public health surveillance; have some idea as to what's behind sentinel and syndromic surveillance; identify sources of data commonly used for public health surveillance; and describe the public health surveillance process. Here's a list of resources.
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I encourage you all to take a look at these. I encourage you to learn more about surveillance. There is a set of resources and readings at the end. Check these out and keep these things in mind as you work with surveillance systems in the future. Those of you who've been around, use your experience and knowledge of both science and the cultural nature of your communities to understand and improve your surveillance systems. Informatics and electronic data systems
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will revolutionize the field, but we still need to understand the system and not turn surveillance into a black box type process. Thank you very much.
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To receive continuing education units, CEU credit, for today's webinar, please complete the weapon our evaluation on CDC Train by logging in and looking under My Learning. If you or one of your colleagues were not able to fully attend or attend today's webinar, an archived version of this webinar will be available on CDC Train in approximately two weeks. For further information, please visit www.dcd.gov/labtraining. Again, thank you for participating in today's webinar.
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Have a positive and healthy afternoon.
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