The main objective of the Surveillance, Monitoring and Reporting unit is to support the collection, analysis, and dissemination of country-level risk factor information to inform and improve public health policy. Healthcare workers need to be aware of the confidentiality issues relevant to collection, management and sharing of data. Source: Ramsey AH, Belongia EA, Gale CM, Davis JP. Case Definitions Meningococcal Disease. MMWR 2004;53:6324. For example, a child with measles in a community with other susceptible children may prompt a vaccination campaign before an investigation of how that child became infected. For other diseases and conditions, the expected number may be based on locally available data such as hospital discharge records, mortality statistics, or cancer or birth defect registries. Staff from different agencies have different perspectives, approaches, and priorities that must be reconciled. Steps in carrying out surveillance (go to Outline) But surveillance involves carrying out many integrated steps by many people: Reporting Someone has to record the data. Using the dates of onset listed below, draw an epidemic curve. Subtract the time of onset of the earliest cases from the time of exposure to estimate the minimum incubation period. Emerg Infect Dis 2002;8:101928. If exposure is much more common among the case-patients than among the controls, i.e., the observed exposure among case-patients is greater than expected exposure provided by the controls, then exposure is said to be associated with illness. Atlanta: CDC; [updated 1999 Oct; cited 2006 Sep 19]. Finally, a p-value or confidence interval is calculated to assess statistical significance. If you have questions about the laboratory findings (for example, if the laboratory tests are inconsistent with the clinical and epidemiologic findings), ask a qualified laboratorian to review the laboratory techniques being used. Data collection tools. Pro 5. The classic epidemic curve, such as the one shown in Figure 6.2a from an outbreak of Salmonella enterica serotype Enteritidis, graphs the number of cases by date or time of onset of illness. The incubation period for hepatitis A ranges from 15 to 50 days (roughly 2 to 7 weeks), with an average incubation period of 2830 days (roughly one month). In practice, choosing who the most appropriate control group is may be quite difficult. Use end-to-end encryption. Laboratory analysts subsequently isolated the outbreak strain of S.Muenchen from several samples of marijuana provided by case-patients. The investigation of an outbreak from an animal source may include state and federal departments of agriculture and/or the Food and Drug Administration (FDA). An epidemic curve that has a steep upslope and a more gradual down slope (a so-called log-normal curve) is characteristic of a point-source epidemic in which persons are exposed to the same source over a relative brief period. : Yes; Lab Results: WB IgG+; Comments: Arthritis, arthralgias, headache, fatigue, sweats, chills; Physician Reporting: Dr. Howard; Phone: 555-1950; Date of Report: 11/24/06. Probable: A suspected case as defined above and turbid CSF (with or without positive Gram stain) or ongoing epidemic and epidemiological link to a confirmed case. In the outbreak setting, the investigators would need to specify time and place to complete the outbreak case definition. The population attributable risk percent describes the proportion of illness in the entire study population that could be attributable to a given exposure, assuming that those who became ill in the unexposed group and a similar proportion in the exposed group must be attributable to something else. Finally, recall that one reason to investigate outbreaks is research. For example, in an outbreak of listeriosis in 2002 caused by contaminated sliceable turkey deli meat, announcements in the media alerted the public to avoid the implicated product and instructed them to see a physician if they developed symptoms compatible with the disease in question.(27). Use a camera to photograph working or environmental conditions. For example, in many hospital outbreaks, investigators use an initial study to narrow their focus. Snow J. fdoov 7khvh vwhsv pd\ khos lq ilhoglqj lqyhvwljdwruv idvwhu dqg lqlwldwlqj dq lqyhvwljdwlrq ,w lv dovr yhu\ grhv wkh /+' kdyh wkh phdqv wr surshuo\ frqgxfw wkh lqyhvwljdwlrq ru lv wkhuh d qhhg wr vhhn rxwvlgh dvvlvwdqfh" ,i dq rxweuhdn lqyhvwljdwlrq uhtxluhv dgglwlrqdo uhvrxufhv .'3+ Develop Community Partnerships. Consider, for example, the outbreak of hepatitis A illustrated by the epidemic curve in Figure 6.5. To apply this test, calculate the chi-square statistic, then look up its corresponding p-value in a table of chi-squares, such as Table 6.10. 5S is the perfect tool to identify the first improvement projects in your company to eliminate waste. (24) Here you can see the different categories that PAHO uses for this diagnosis. You will be subject to the destination website's privacy policy when you follow the link. Available from: The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website. While epidemiology can implicate vehicles and guide appropriate public health action, laboratory evidence can confirm the findings. The circumstances may allow you to learn more about the disease, its modes of transmission, the characteristics of the agent, host factors, and the like. This approach ensures that the investigation proceeds without missing important steps along the way. Whichever decision you make, you may be right or you may be wrong. If a highly publicized mass gathering potentially attracts terrorists (e.g., a championship sporting event or political convention), how might a health department detect the presence of biologic agents or the outbreak of a disease the agent might cause? Some interventions aim to increase a hosts defenses. Drawing an epidemic curve. Figure 6.7 shows the location of staff in two offices in the U.S. Senates Hart Building who had nasal swabs positive for B. anthracis after an envelope containing anthrax spores was opened in their presence.(33). How is it usually transmitted? Table 6.9 Standard Notation of a Two-By-Two Table. Administration officials say the . 1. The earliest case occurred during the week of October 28. Capt. For example, whereas the public health investigation may focus on identifying a pathogen, source, and mode of transmission, a criminal investigation is likely to focus on finding the perpetrator. Overall, nearly nine-in-ten respondents say they have heard at least a bit about the government surveillance programs to monitor phone use and internet use. Why do the people living in one particular area have the highest attack rate? Bopp DJ, Saunders BD, Waring AL, Waring AL, Ackelsberg J, Dumas N, et al. This association was confirmed in the laboratory, where the outbreak subtype of the Legionnaires disease bacillus was isolated from the water in the mist machines reservoir. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page. For airborne diseases, strategies may be directed at modifying ventilation or air pressure, and filtering or treating the air. You are called to help investigate a cluster of 17 persons who developed brain cancer in an area over the past couple of years. In analytic epidemiology, inclusion of false-positive cases can produce misleading results. Presented at the 53rd Annual Epidemic Intelligence Service Conference; 2004 Apr 1923; Atlanta. Is the attack rate low among persons not exposed to that item? Some epidemiologists apply the term epidemic to situations involving larger numbers of people over a wide geographic area. However, in many outbreak settings, the population is not well defined and speed of investigation is important. These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. Feedback on . Case-patients did, controls did not.(37). Becker KM, Moe CL, Southwick KL, MacCormack JN. Positive feedback, asking for reviews and recommendations generates trust. Epidemiol Bull 2001;22(4):146. Response is the how organizations respond to whatever challenges disasters bring such as supply chain . The lesson learned is that when the epidemiology does not fit the usual or natural patterns of transmission, investigators should think about intentional modes of transmission. Epidemiologic clues to bioterrorism. Outliers also can provide important clues. New York: Oxford U Press, 2001:129. Josh Shapiro wants lawmakers to pass a three-year incentive of up to $2,500 a year for newly certified teachers, police officers and nurses in Pennsylvania. A systematic difference between cases and controls that results in a mistaken estimate of the association between exposure and disease is called a bias. Source: Jani AA, Barrett E, Murphy J, Norton D, Novak C, Painter J, Toney D. A steamship full of trouble: an outbreak of Salmonella Typhimurium DT 104 gastroenteritis at a holiday banquetVirginia, 2003. : Yes; Hospital Alerted: Yes; Lab Results: WB IgM+, WB IgG+; Comments: Erythema migrans; Physician Reporting: Dr. Howard; Phone: 555-1950; Date of Report: 11/24/06. Return to text. Consider the gastroenteritis and beef consumption data presented in Table 6.8. Communitywide outbreak of Legionnaires disease associated with a grocery store mist machine. Refer to the book or to the electronic PDF version (511 pages) for printable versions of text, figures, and tables. First, you must continue to monitor the situation and determine whether the prevention and control measures are working. Often, the number of case-patients that can be enrolled in a study is limited by the size of the outbreak. They can use closed circuit television to. A spot map is a simple and useful technique for illustrating where cases live, work, or may have been exposed. Even if the current number of reported cases exceeds the expected number, the excess may not necessarily indicate an outbreak. The greater the difference in attack rates between the exposed and unexposed groups, the larger the relative risk, and the stronger the association between exposure and disease. If the tests confirm that all of those case-patients were infected with the same organism, for example norovirus, the other persons with compatible clinical illness are all presumed to be part of the same outbreak and to be infected with the same organism. The following 10 suggestions will help you conduct a more cost-effective and successful surveillance. What additional information might be helpful in making this determination? Using the information about disease and exposure status, the investigator then calculates an odds ratio to quantify the relationship between exposure and disease. An intentional act, one with either terrorist or criminal intent, should be considered under a variety of circumstances listed in Table 6.6. Frequency distributions of the clinical features are useful in characterizing the spectrum of illness, verifying the diagnosis, and developing case definitions. Finally, before departing, you should have a plan of action. In general, the more subjects (case-patients and controls) in a study, the easier it will be to find a statistically significant association. Classifications such as confirmed-probable-possible are helpful because they provide flexibility to the investigators. Return to text. The World Health Organization (WHO) defines public health surveillance as the "continuous, systematic collection, analysis and interpretation of health-related data needed for the planning, implementation, and evaluation of public health practice. Table 6.3 Line Listing of 7 Persons with Suspected Eosinophilia-myalgia, * Severe enough to affect the patients ability to pursue usual daily activities, Eventually, public health officials agreed on the following revised case definition:(26). Then calculate a chi-square or other statistical test. Considering the third criterion listed earlier, notice that almost all (53 out of 57) of the cases could be accounted for by the beef. The two most common types of analytic epidemiology studies used in field investigations are retrospective cohort studies and case-control studies, as described in the following sections. While Jackson (n=11) and Rusk (n=9) Counties had fewer cases than Chippewa, their populations are much smaller, and they turned out to have higher rates of disease. Confirmed: A suspected or probable case with laboratory confirmation. For a case-control study, the measure of association of choice is the odds ratio. Tan C. A preventable outbreak of pneumococcal pneumonia among unvaccinated nursing home residents New Jersey, 2001. In an outbreak context, hypotheses are generated in a variety of ways. Saving Lives, Protecting People, Principles of Epidemiology in Public Health Practice, Third Edition, Find cases systematically and record information, As necessary, reconsider, refine, and re-evaluate hypotheses, Compare and reconcile with laboratory and/or environmental studies, Implement control and prevention measures, /nchstp/tb/pubs/ssmodules/module7/ss7background.htm, 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, A peripheral eosinophil count of 1,000 cells/mm. Numbers indicate the burden of disease and are useful for planning and service delivery. Usually, the cases are presumed to have a common cause or to be related to one another in some way. In this outbreak, the association between eating beef at the banquet and gastroenteritis was both strong (RR=5.7) and statistically significant (p < 0.001). Reporting may rise because of changes in local reporting procedures, changes in the case definition, increased interest because of local or national awareness, or improvements in diagnostic procedures. Knowing the likely period of exposure allows you to ask questions about the appropriate period of time so you can identify the source of the epidemic. Blank S, Scanlon KS, Sinks TH, Lett S, Falk H. An outbreak of hypervitaminosis D associated with the overfortication of milk from a home-delivery dairy. It's easy to say that you'll exercise every day. The itineraries were similar. Figure 6.2b Outbreak of SalmonellaEnteritidis Gastroenteritis Maryland, 2003 (Epidemic Curve by 6-Hour Intervals). Some outbreak investigations require no special equipment while an investigation of SARS or Ebola hemorrhagic fever may require personal protective equipment such as masks, gowns, and gloves. : Yes; Hospital Alerted: Yes; Lab Results: WB IgM+; Comments: Erythema migrans; fatigue, sweats, chills; Physician Reporting: Dr. In that situation, it may be useful to draw several epidemic curves with different units on the x-axis to find one that best portrays the data. Here are five key steps to conducting a proper workplace investigation. Epidemiological Bulletin 2002; 22(4):145. For example, investigators of an outbreak of hepatitis B might characterize the cases by intravenous drug use and sexual contacts, two of the high risk exposures for that disease. Your literature review should be guided by a central research question. Second, many investigators clinicians and non-clinicians find it useful to visit one or more patients with the disease. Surveillance identifies new cases and detects importation of wild poliovirus The four steps of surveillance are: 1. Manual. Research for a new drug begins in the laboratory. A case might be temporarily classified as probable or possible while laboratory results are pending. Sample size formulas are available to help you make this decision. Single case of disease caused by an uncommon agent (e.g., glanders, smallpox, viral hemorrhagic fever, inhalational or cutaneous anthrax) without adequate epidemiologic explanation, Unusual, atypical, genetically engineered, or antiquated strain of an agent (or antibiotic-resistance pattern), Higher morbidity and mortality in association with a common disease or syndrome or failure of such patients to respond to usual therapy, Unusual disease presentation (e.g., inhalational anthrax or pneumonic plague), Disease with an unusual geographic or seasonal distribution (e.g., tularemia in a non-endemic area, influenza in the summer), Stable endemic disease with an unexplained increase in incidence (e.g., tularemia, plague), Atypical disease transmission through aerosols, food, or water, in a mode suggesting deliberate sabotage (i.e., no other physical explanation), No illness in persons who are not exposed to common ventilation systems (have separate closed ventilation systems) when illness is seen in persons in close proximity who have a common ventilation system, Several unusual or unexplained diseases coexisting in the same patient without any other explanation, Unusual illness that affects a large, disparate population (e.g., respiratory disease in a large population may suggest exposure to an inhalational pathogen or chemical agent), Illness that is unusual (or atypical) for a given population or age group (e.g., outbreak of measles-like rash in adults), Unusual pattern of death or illness among animals (which may be unexplained or attributed to an agent of bioterrorism) that precedes or accompanies illness or death in humans, Unusual pattern of death or illness among humans (which may be unexplained or attributed to an agent of bioterrorism) that precedes or accompanies illness or death in animals, Ill persons who seek treatment at about the same time (point source with compressed epidemic curve), Similar genetic type among agents isolated from temporally or spatially distinct sources, Simultaneous clusters of similar illness in noncontiguous areas, domestic or foreign, Large number of cases of unexplained diseases or deaths. Review the six case report forms in Figure 6.1. As noted earlier, many outbreaks are brought to the attention of health authorities by concerned healthcare providers or citizens. Descriptive epidemiology describes the where and whom of the disease, allowing you to begin intervention and prevention measures. The answer is public health surveillance. 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. As a field investigator, you must have the appropriate scientific knowledge, supplies, and equipment to carry out the investigation before departing for the field. The team members must be selected before departure and know their expected roles and responsibilities in the field. Centers for Disease Control and Prevention. 5 BIOSURVEILLANCE SYSTEMS The definitions of biosurveillance, disease surveillance, and public health surveillance all include the word systematic. For a notifiable disease, the expected number is based on health department surveillance records. A good field investigator must be a good manager and collaborator as well as a good epidemiologist, because most investigations are conducted by a team rather than just one individual. In response, health departments have made great strides in attempting to keep the public informed. Cookies used to make website functionality more relevant to you. This part includes the STEPS Instrument as well as the question-by-question guide, the show cards, and . Hedberg CW, Fishbein DB, Janssen RS, Meyers B, McMillen JM, MacDonald KL, et al. In studying sick-building syndrome and other disorders related to air-flow patterns in buildings, cases should be plotted by work location. Similarly, prophylactic use of antimalarial drugs, recommended for visitors to malaria-endemic areas, does not prevent exposure through mosquito bites but does prevent infection from taking root. What is the appropriate measure of association? Its purpose is to provide a factual basis from which agencies can appropriately set priorities, plan programs, and take actions to promote and protect the public's health. You can review and change the way we collect information below. Consider convening a meeting of the case-patients to look for common links or visiting their homes to look at the products on their shelves. The controls provide the level of exposure you would expect to find among the case-patients if the null hypothesis were true. A narrow confidence interval indicates that the risk ratio is fairly precise. MacDonald KL, Spengler RF, Hatheway CL, Hargrett NT, Cohen ML. If you need specialized laboratory work such as confirmation in a reference laboratory, DNA or other chemical or biological fingerprinting, or polymerase chain reaction, you must secure a sufficient number of appropriate specimens, isolates, and other laboratory material as soon as possible. For example, in a hospital, four or five cases may constitute an outbreak. Investigators then abstract selected critical items onto a form called a line listing (See Lesson 2 for more information on line listings.
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