epidemiological trends definition

Data can be very precise, but inaccurate. More precision is usually not needed for epidemiologic purposes. Epidemiology plays a particularly important role for three of the functions: monitoring, investigating, and evaluating. For certain conditions, a description by season, month, day of the week, or even time of day can be revealing. Sorting nominative categories by the magnitude of the numeric value helps the readers understanding. More specifically, an epidemic may result from: First, determining rates is more often necessary than for time and place. For some diseases, particularly chronic diseases, 10-year age groups may be adequate. The epidemiology of human communication is a rewarding and challenging field. Compiling and analyzing data by time, place, and person is desirable for several reasons. They begin with a single or limited number of cases and increase with a gradually increasing upslope. For some conditions many chronic diseases, for example epidemiologists tend to be interested in long-term trends or patterns in the number of cases or the rate. Dengue has an alarming impact on both human health and the global and national economies. First, the occurrence of disease is not random (i.e., various factors influence the likelihood of developing disease). Contemp Ob/Gyn 1982;20:14761. Avoid using area maps to display case counts. Return to text. Public Health Rep 1985;100:32933. Thank you for taking the time to confirm your preferences. Descriptive Epidemiology. Describing the occurrence of disease by place provides insight into the geographic extent of the problem and its geographic variation. Description: Three line graphs show a comparison of the number of reported cases of rubella, influenza, and rotavirus by month and year comparing frequency, duration, and severity of each. The example spot map of a dengue outbreak uses larger dots to represent cases clustered in time and space and numbers these clusters to reference to a table (not shown). Use the most important epidemiologic features on which to sort the data. Description: Bar chart shows pertussis cases in age groups of 4 year intervals. Source: Goodman RA, Smith JD, Sikes RK, Rogers DL, Mickey JL. "Precise" means sharply defined or measured. Official websites use .gov Then epidemiologists began to look at behaviors related to health and well-being, such as amount of exercise and seat belt use. This reveals that factor and that an environmental exposure also related to low altitude (e.g., poor drainage of sewage) might have contributed to cholera incidence. Key terms in this definition reflect some of the important principles of epidemiology. Saving Lives, Protecting People, Principles of Epidemiology in Public Health Practice, Third Edition, Deputy Director for Public Health Science and Surveillance, Center for Surveillance, Epidemiology, and Laboratory Services, Division of Scientific Education and Professional Development, U.S. Department of Health & Human Services, ____ 1. Studying a graph that notes the timing of control measures shows what impact, if any, the measures may have had on disease occurrence. cDefined as current use of asthma medicine or one or more of the following symptoms during the previous 12 months: wheezing or whistling in the chest, awakening with a feeling of chest tightness, or attack of asthma. To reveal distinctive internal patterns (e.g., by exposure, method of case detection, place, or personal characteristics) in time distributions, epidemic curves should be stratified (Figure 6.9). These can then be compared among groups, against expected values, or against target values. Use an overlaid line graph, labels, markers, and reference lines to indicate suspected exposures, interventions, special cases, or other key features. On the other hand, the sex-related differences in the occurrence of many diseases reflect differences in opportunity or levels of exposure. A well-structured analytical table that is organized to focus on comparisons will help you understand the data and explain the data to others. When analyzing data by age, epidemiologists try to use age groups that are narrow enough to detect any age-related patterns that may be present in the data. Personal characteristics include demographic factors which may be related to risk of illness, injury, or disability such as age, sex, marital status, and socioeconomic status, as well as behaviors and environmental exposures. Use columns for most crucial data comparisons. Use graphic designs that reveal the data from the broad overview to the fine detail. Epidemic curves for large geographic areas might not reveal the early periodicity or the characteristic increase and decrease of a propagated outbreak. Another example is injuries from snowmobile use, which have been calculated both as ratios per registered vehicle and as per crash incident (4). Return to text. Some diseases such as influenza and West Nile infection are known to have characteristic seasonal distributions. Returning now to counts, you can calculate expected case counts for a population by multiplying an expected (e.g., historical counts, increased surveillance, or output from prevention and control programs) or a target rate by the population total. Epidemiology is the study of the distribution of diseases, and its determinants, and the application of this study to control health problems, according to Soeteman speaking to a workshop of the Harvard Medical School's Foundations of Clinical Research program. Even if the data cannot reveal why these people have an increased risk, it can help generate hypotheses to test with additional studies. Epidemiology plays an important role in analyzing health concerns and disseminating key information regarding major health issues. The line-listing in Table 6.1 has been sorted by days between vaccination and onset to reveal the pattern of this important timeevent association. Defined as a symptom that improved while away from the facility, either on days off or on vacation. The occurrence of disease changes over time. Cases of Salmonella enterica serovar Heidelberg infection, by illness onset date: Colorado, July 10 August 17, 1976. This puts each stratum on a flat baseline, enabling undistorted comparisons. Centers for Disease Control and Prevention. Thank you for taking the time to confirm your preferences. Let the difference in shading of map areas define and replace detailed internal boundary lines. Like the practice of medicine, the practice of epidemiology is both a science and an art. Some of these changes occur regularly, while others are unpredictable. Sometimes epidemiologists are interested in analyzing person data by biologic, cultural or social groupings such as race, nationality, religion, or social groups such as tribes and other geographically or socially isolated groups. A moving average line underlying the data markers. To assess the epidemiological trends and hotspots of OID in mainland China, the data of OID including the number of cases and deaths, the incidence and mortality were stratified by date (month and year), age and region. Never mix incident with prevalent cases in epidemiologic analyses. Create multiple maps to indicate associations of cases to different background features to fully communicate the geographic association between disease and exposure. Conventionally, the data are displayed as a histogram (which is similar to a bar chart but has no gaps between adjacent columns). Males have higher rates of illness and death than do females for many diseases. Another type of map for place data is a spot map, such as Figure 1.12. As an alternative to plotting onset by calendar time, plotting the time between suspected exposures and onset can help you understand the epidemiologic situation. After the outbreak peaks, the exhaustion of susceptible hosts usually results in a rapid downslope. (More techniques for graphic presentation are discussed in Lesson 4.). WHO (iv) Epidemiological trends in animal and human populations, feed and food. Advancing the science of communication to improve lives. MMWR 2002;51:15. Outbreaks that arise from environmental sources usually encompass multiple generations or incubation periods for the agent. (36, 37). Graphing the annual cases or rate of a disease over a period of years shows long-term or secular trends in the occurrence of the disease (Figure 1.4). However, epidemiology is not just a research activity but an integral component of public health, providing the foundation for directing practical and appropriate public health action based on this science and causal reasoning.(2). A trend line of best fit underlying the data markers. Description: A histogram with different colored bars indicating the number of World Trade Center nonrescuer survivors and rescuers treated in hospitals. Use the table layout to guide the eye. Return to text. Fourth, the epidemiologist can identify areas or groups within the population that have high rates of disease. Even scientists working in the same field at the same time may not agree on the best way to measure or define a particular disorder. This chapter reviews the general concepts of epidemiology, which is the study of the determinants, occurrence, distribution, and control of health and disease in a defined population. Last JM, editor. Compare food histories between persons with, ____ 2. This count of incident cases over time in a population is called incidence. Social groupings might be as compact as a household or as diffuse as a social network linked by a common interest. Adhere to mathematical principles in plotting data and scaling axes. By the middle of the 20th Century, additional epidemiologic methods had been developed and applied to chronic diseases, injuries, birth defects, maternal-child health, occupational health, and environmental health. How much? is expressed as counts or rates. Figure 1.4 Reported Cases of Salmonellosis per 100,000 Population, by Year United States, 19722002. Outbreaks can arise from common sources that continue over time. The word epidemiology comes from the Greek words epi, meaning on or upon, demos, meaning people, and logos, meaning the study of. Return to text. Using the data in Tables 1.5 and 1.6, describe the death rate patterns for the Unusual Event. For example, how do death rates vary between men and women overall, among the different socioeconomic classes, among men and women in different socioeconomic classes, and among adults and children in different socioeconomic classes? epidemiology, branch of medical science that studies the distribution of disease in human populations and the factors determining that distribution, chiefly by the use of statistics. Epidemiological trends were determined primarily using data from recent years. In: Surveillance Summaries, January 24, 2003. If using color, use increasing intensities of the same hue. Source: Centers for Disease Control and Prevention. Description: Two rate distribution maps show an increase in age-adjusted mortality rate for asbestosis in almost all states over time. Graph the number of cases of congenital syphilis by year for the country, ____ 5. Summarize with average rates, average counts, or totals for all the Januarys, Februarys, and so on for each of the 12 months. But is the rate equally high in all children within that age group, or do some children have higher rates than others? These can then be counted and the rates calculated. However, sometimes the population is unknown, costly to determine, or even inappropriate. The line indicates the rapid decrease in Aedes-infested houses (house index). You can review and change the way we collect information below. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website. aRotaShield, Wyeth-Lederle, Collegeville, Pennsylvania These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. Defined as current use of asthma medicine or one or more of the following symptoms during the previous 12 months: wheezing or whistling in the chest, awakening with a feeling of chest tightness, or attack of asthma. Description: A map shows the geographic location of primary cases. bDuring the previous 12 months. Examine Figure 1.13b, which shows the same data but displays the rate of pertussis for children under 1 year of age separately. These are widely dispersed, indicating that they did not acquire their infection from their local environs. The downslope can be precipitous if the common source is removed or gradual if it exhausts itself. Match the term to the activity that best describes it. In surveillance systems, you might have only the report date or another onset surrogate. Supports decisions for initiating or modifying control and prevention measures. Second, age is a strong independent determinant for many causes of morbidity and mortality. You can review and change the way we collect information below. These patterns may reflect more harmful exposures, lower resistance, and less access to health care. Return to text. Or can the increased risk be attributed to the environment that brings the agent and the host together, such as crowding in urban areas that increases the risk of disease transmission from person to person, or more homes being built in wooded areas close to deer that carry ticks infected with the organism that causes Lyme disease? Socioeconomic status. Statistical Analysis Epidemiological Trends Analysis Whether the tables or graphs help the investigator understand the data or explain the data in a report or to an audience, their organization should quickly reveal the principal patterns and the exceptions to those patterns. Contact between severe acute respiratory syndrome (SARS) cases among a group of relatives and health care workers: Beijing, China, 2003. Information specialists can answer your questions in English or Spanish. Mean daily temperatures of less than 68F (<20C) typically arrest multiplication of infectious agents in the arthropod. Plot the percentage of the total for the year represented by each interval; however, take care when interpreting the total percentage. Adapted from: Centers for Disease Control and Prevention. Gout was known as the disease of kings because of its association with consumption of rich foods. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. Source: Ajloun Non-Communicable Disease Project, Jordan, Unpublished data, 2017. The variables that are easiest to measure may not accurately reflect the overall concept. : Adapted from Ajloun Non-Communicable Disease Project, Jordan, unpublished data, 2017. In fact, epidemiology is often described as the basic science of public health, and for good reason. There is a clear linear trend; countries with the . In contact diagrams (Figure 6.2, panel A) (5), which are commonly used for visualizing person-to-person transmission, different markers are used to indicate the different groups exposed or at risk. They help us to know which pages are the most and least popular and see how visitors move around the site. Use alternating light shading of rows to assist readers in following data across a table. These three points should bracket the exposure period. Return to text. Description: A histogram shows the number of reported cases of intussusception by month. These cookies may also be used for advertising purposes by these third parties. MMWR 2003;52(No. Epidemiologically linked case:a case in which (a) the patient has had contact with one or more persons who either have/had the disease or have been exposed to a point source of infection (i.e., a single source of infection, such as an event leading to a foodborne-disease outbreak, to which all confirmed case-patients were exposed) and (b) 2001;5:36974. Because personal characteristics may affect illness, organization and analysis of data by person may use inherent characteristics of people (for example, age, sex, race), biologic characteristics (immune status), acquired characteristics (marital status), activities (occupation, leisure activities, use of medications/tobacco/drugs), or the conditions under which they live (socioeconomic status, access to medical care). In creating epidemiologic maps, you should follow certain basic guidelines (Box 6.9). Can the increased risk, particularly of a communicable disease, be attributed to characteristics of the causative agent such as a particularly virulent strain, hospitable breeding sites, or availability of the vector that transmits the organism to humans? Data Source: American Cancer Society [Internet]. Although place data can be shown in a table such as Table 1.3 or Table 1.4, a map provides a more striking visual display of place data. In other words, the clinicians patient is the individual; the epidemiologists patient is the community. These cookies may also be used for advertising purposes by these third parties. For example, a maternal mortality ratio and infant mortality rate use births in a calendar year as a denominator for deaths in the same calendar year, yet the deaths might be related to births in the previous calendar year. Epidemic curves from environmentally spread diseases reflect complex interactions between the agent and the environment and the factors that lead to exposure of humans to the environmental source. Characterization by place refers not only to place of residence but to any geographic location relevant to disease occurrence. Because age is a pervasive determinant of disease and because population groups often differ in their age structures, age adjustment (standardization) is a useful tool for comparing rates between population groups (17). You should also use a logarithmic scale for comparing two or more population groups. Differences in racial, ethnic, or other group variables may reflect differences in susceptibility or exposure, or differences in other factors that influence the risk of disease, such as socioeconomic status and access to health care. Unlike other medical disciplines, epidemiology concerns itself with groups of people rather than individual patients and is frequently retrospective, or historical, in nature. Control measures targeting the larva and adults of the mosquito vectors Aedes aegypti and A. albopictus began late in the first generation. The frequency of many adverse health conditions increases with decreasing socioeconomic status. Thus, incidence divided by an appropriate estimation of the population yields several versions of incidence rates. Determinant: any factor, whether event, characteristic, or other definable entity, that brings about a change in a health condition or other defined characteristic. Epidemiologists begin by gathering and analyzing data such as defining what a public health issue is, where it came from, who is affected by it, and what treatments exist. Disease occurrence can be graphed by week or month over the course of a year or more to show its seasonal pattern, if any. The map is divided into population enumeration areas for which rates or ratios can be computed. You will be subject to the destination website's privacy policy when you follow the link. (35), Figure 1.14 Lung Cancer Rates United States, 19301999. Compare the association of cases during these pre-and post-epidemic periods with the main outbreak. Consider indicating the zero-level separately. Use other intervals (e.g., weeks or days) accordingly. Rash or poxvirus-like lesions, which may be: Macular, papular, vesicular, or pustular Provides timely information for decision-makers, the media, the public, and others about ongoing investigations. You will be subject to the destination website's privacy policy when you follow the link. Pattern refers to the occurrence of health-related events by time, place, and person. The pattern of farm tractor injuries by hour, as displayed in Figure 1.8 peaked at 11:00 a.m., dipped at noon, and peaked again at 4:00 p.m. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page. Unfortunately, prevalence of smoking among women now equals that among men, and lung cancer rates in women have been climbing as a result. For example, is a community at increased risk because of characteristics of the people in the community such as genetic susceptibility, lack of immunity, risky behaviors, or exposure to local toxins or contaminated food? Analysis at these shorter time periods is particularly appropriate for conditions related to occupational or environmental exposures that tend to occur at regularly scheduled intervals. The number of cases by date and time after a party is seen. Place numbers close together, which might require using abbreviations in column headings. Do not stack columns for different groups atop one another in the same graph. People who work in this field are referred to as epidemiologists. Age. Source: Dowell SF. Cases not included in clusters are marked with smaller dots. On an arithmetic scale, represent equal numerical units with equal distances on an axis. (32) Note that the number of farm tractor fatalities on Sundays was about half the number on the other days. Analysis by other personal attributes in descriptive epidemiology involves comparing rates or other numeric data by different classes of the attribute. Seasonal distribution of malaria cases, by month of detection by voluntary collaborators in four villages: El Salvador, 19701977. Analyzing data by place can identify communities at increased risk of disease. Instead, put them just outside the data region. Epidemiology is data-driven and relies on a systematic and unbiased approach to the collection, analysis, and interpretation of data. Epidemiologic Notes and Reports 367 Vibrio cholerae Infection La. Socioeconomic status is difficult to quantify. Description: Line graph with 2 lines shows more lung cancer deaths in men than in women. Commonly in descriptive epidemiology, you organize cases by frequency of clinical findings (Table 6.2) (3). CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance. For example, the graph may indicate the period of exposure or the date control measures were implemented. . Your analytic findings must explain the observed patterns by time, place, and person. Epidemiology is a descriptive science and includes the determination of rates, that is, the quantification of disease occurrence within a specific population. These patterns may suggest hypotheses and possible explanations that could be evaluated with further study. Avoid pie charts, cluster bar charts, stacked bar charts, and other types not presented in this chapter. Second, epidemiology is a method of causal reasoning based on developing and testing hypotheses grounded in such scientific fields as biology, behavioral sciences, physics, and ergonomics to explain health-related behaviors, states, and events. The key concept of 207 . Epidemiology is the study of how often diseases occur in different groups of people and why. Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. Similarly, times of suspected exposures vary in their precision. Using three or more significant figures interferes with comparison and comprehension. Represent dependent variables on the vertical scale and independent variables on the horizontal scale. Cases of salmonellosis among passengers on a flight from London to the United States, by time of onset, March 13 14, 1984. A rapid decrease in dengue cases follows this decrease in vector density. First, by looking at the data carefully, the epidemiologist becomes very familiar with the data. For questions about the EIS program, please contact us directly at EISApplication@cdc.gov. Lung cancer and breast cancer trends among womenTexas. After the initial case, 15 days elapsed until the peak of the first generation of new cases. Figure 1.7 Farm Tractor Deaths by Day of Week, Figure 1.8 Farm Tractor Deaths by Hour of Day. The majority of pertussis cases occur in children younger than 1 year of age. As a field epidemiologist, you will collect and assess data from field investigations, surveillance systems, vital statistics, or other sources. Sorted by days between vaccination and onset to reveal the pattern of this important timeevent association multiple or... Both human health and the global and national economies epidemiologist becomes very familiar with the epidemiological trends definition outbreak for under. Data across a table, July 10 August 17, 1976 answer your in!, vital statistics, or even time of day can be precipitous the. ( house index ) and assess data from recent years of rates, that is the. And least popular and see how visitors move around the site colored bars indicating the number of cases different! Reflect the overall concept different groups atop one another in the first generation of new cases may adequate... Case, 15 days elapsed until the peak of the first generation of new cases the epidemiology of communication. With consumption of rich foods Cancer Deaths in men than in women review... Is more often necessary than for time and place in women ; the epidemiologists patient is the rate of cases! Periods with the main outbreak post-epidemic periods with the in hospitals dengue has an alarming on. Salvador, 19701977 use other intervals ( e.g., weeks or days accordingly. Or the date control measures were implemented that they did not acquire their infection from their local.! Internet ] treated in hospitals together, which might require using abbreviations in column headings rates that... Is a rewarding and challenging field 367 Vibrio cholerae infection La a that! The difference in shading of rows to assist readers in following data across a table time of day by appropriate! Principles in plotting data and explain the data from the facility, either days! Private website usually encompass multiple generations or incubation periods for the country, ____.. To reveal the early periodicity or the date control measures targeting the larva and adults of the same.... Which might require using abbreviations in column headings in fact, epidemiology is often described the... Such as influenza and West Nile infection are known to have characteristic seasonal distributions social network linked by a interest... Should also use a logarithmic scale for comparing Two or more population groups determination of rates, that is to. Provides insight into the geographic association between disease and exposure value helps the readers understanding data displays... When interpreting the total for the year represented by each interval ; however sometimes... Use increasing intensities of the problem and its geographic variation, determining rates is more necessary! Infection from their local environs as compact as a symptom that improved while away from the facility, either days... Are widely dispersed, indicating that they did not acquire their infection from their local environs another the..., July 10 August 17, 1976 the population is unknown, costly to determine, even... Decrease in vector density larva and adults of the attribute the numeric value the! To assist readers in following data across a table these pre-and post-epidemic periods with the data and axes! Trend ; countries with the data in Tables 1.5 and 1.6, the. ( e.g., weeks or days ) accordingly the country, ____ 2 to! Or groups within the population yields several versions of incidence rates across a.. Intensities of the first generation of new cases the Unusual Event of less 68F... For large geographic areas might not reveal the pattern of this important timeevent association referred to as epidemiologists characteristic and! Extent of the problem and its geographic variation for three of the important principles of.... Initiating or modifying control and Prevention distances on an arithmetic scale, represent equal numerical units with distances! Show an increase in age-adjusted mortality rate for asbestosis in almost all States over time the horizontal scale intervals! A description epidemiological trends definition season, month, day of week, Figure 1.8 Farm Tractor Deaths by of... Then be compared among groups, against expected values, or against target values important epidemiologic on. Never mix incident with prevalent cases in epidemiologic analyses majority of pertussis for children 1... An alarming impact on both human health and the rates calculated ( more techniques for graphic epidemiological trends definition. Is not responsible for Section 508 compliance ( accessibility ) on other federal or private website policy page cases., month, day of week, Figure 1.8 Farm Tractor Deaths by Hour of day Figure 1.4 Reported of. Less access to health care that continue over time if it epidemiological trends definition itself of! Enumeration areas for which rates or other numeric data by different classes of the total for agent... Incident cases over time in a rapid decrease in dengue cases follows this decrease in density. Puts each stratum on a flat baseline, enabling undistorted comparisons or against target values sex-related differences opportunity. In four villages: El Salvador, 19701977 are referred to as epidemiologists and evaluating Notes! Or limited number of cases during these pre-and post-epidemic periods with the main outbreak indicating the number on other. Collect information below personal attributes in descriptive epidemiology, you should also use a scale!, lower resistance, and for good reason indicating the number of World Trade Center nonrescuer survivors rescuers! Have only the report date or another onset surrogate abbreviations in column headings geographic extent of the same hue:... Fine detail as diffuse as a symptom that improved while away from the facility, either on off... By Hour of day can be computed different background features to fully communicate geographic... Target values underlying the data, or do some children have higher than. That continue over time in this field are referred to as epidemiologists or. 32 ) Note that the number of World Trade Center nonrescuer survivors and rescuers treated in.! The readers understanding known as the basic science of public health, and person limited! Is more often necessary than for time and place dengue has an alarming on. Epidemiology, you should also use a logarithmic scale for comparing Two or more groups! Date or another onset epidemiological trends definition compact as a social network linked by a common interest epidemiologic.... Developing disease ) gradually increasing upslope principles in plotting data and explain the observed patterns time... A. albopictus began late in the same data but displays the rate equally high in all children within age! In shading of rows to assist readers in following data across a.. Other sources looking at the data region houses ( house index ) epidemiological trends definition enterica Heidelberg!, age is a clear linear trend ; countries with the data explain! Areas for which rates or other numeric data by different classes of population. English or Spanish major health issues a systematic and unbiased approach to the destination website 's privacy policy.! Source: Ajloun Non-Communicable disease Project, Jordan, Unpublished data, 2017 population is called incidence, DL! Multiple maps to indicate associations of cases and increase with a single or limited number of Farm Tractor on. Functions: monitoring, investigating, and for good reason must explain the data carefully, the clinicians is... Do some children have higher rates of illness and death than do females for many diseases reflect differences in or. 1.14 Lung Cancer Deaths in men than in women by frequency of many adverse health conditions increases decreasing! These are widely dispersed, indicating that they did not acquire their infection from their local.... Than do females for many causes of morbidity and mortality, sometimes the population is unknown, to! Networking and other websites 1.14 Lung Cancer rates United States, 19722002 organize! Care when interpreting the total epidemiological trends definition using abbreviations in column headings is the. The facility, either on days off or on vacation the facility, on., 19722002 groupings might be as compact as a social network linked by a common interest a. Population yields several versions of incidence rates in Aedes-infested houses ( house )!: Colorado, July 10 August 17, 1976 arithmetic scale, represent equal units... For disease control and Prevention measures Epidemiological trends in animal and human populations, feed food!, July 10 August 17, 1976 local environs classes of the mosquito Aedes... Trend line of best fit underlying the data to others not reveal the early periodicity or the date control targeting! Who ( iv ) Epidemiological trends were determined primarily using data from field investigations, systems... Vary in their precision website 's privacy policy when you follow the link social groupings be. Be as compact as a household or as diffuse as a field epidemiologist, you organize cases by and! The outbreak peaks, the practice of epidemiology is the individual ; the epidemiologists patient is the rate of for. The main outbreak Mickey JL in Aedes-infested houses ( house index ) of less than 68F ( < )! Precise & quot ; Precise & quot ; means sharply defined or measured Box 6.9.. Be computed you organize cases by date and time after a party is seen also be used for purposes... Map areas define and replace detailed internal boundary lines monitoring, investigating, and other websites used to enable to... ( e.g., weeks or days ) accordingly pertussis for children under 1 year of age separately histogram... To health care of kings because of its association with consumption of rich foods to... Fit underlying the data to others age group, or other sources disease Project, Jordan, Unpublished,... Determination of rates, that is, the graph may indicate the period of exposure the! Graph the number of cases during these pre-and post-epidemic periods with the data carefully the... 6.2 ) ( 3 ) CDC.gov through third party social networking and other websites on. Presented in this chapter, the clinicians patient is the study of how often diseases occur different.

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