what are the three principles of outbreak management

Later on, when hypotheses have come into sharper focus, the investigator may tighten the case definition by dropping the possible and sometimes the probable category. You do not currently have access to this chapter. Legionnaires disease: description of an epidemic of pneumonia. 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. Data Source: Mahoney FJ, Hoge CW, Farley TA, Barbaree JM, Breiman RF, Benson RF, McFarland LM. deploying staff who have not been vaccinated to other areas, or excluding them. provided by the manufacturers and the most recent codes of conduct and safety regulations. Guiding Principles for Outbreak Management Arrangements 3 | P a g e Purpose of document This document is intended to outline principles for the design of COVID-19 Local Outbreak Plans led by the Director of Public Health at Upper Tier Local Authority level, working with Depending on the type of outbreak, the number of involved agencies may be quite large. Feed and water consumption and production should be carefully monitored at all times, as well as the typical sounds and behaviors of individual animals. Develop case definition 5. There are three types of transmission-based precautions: contact precautions, droplet precautions and airborne precautions. J Infect Dis 1992;165: 7369. As noted earlier, the severity of the illness, the potential for spread, availability of control measures, political considerations, public relations, available resources, and other factors all influence the decision to launch a field investigation. Definitions 3. A timely investigation has for aim to identify the source and vehicle of the outbreak and provides unique opportunities to better understand its occurrence and the role of contributing risk factors to implement the most appropriate measures to control it and prevent further recurrences. You can review and change the way we collect information below. We've encountered a problem, please try again. In most case-control studies, the population is not well defined, and the total number of people exposed (or unexposed) to a suspected vehicle or source is not known. If you see Sign in through society site in the sign in pane within a journal: If you do not have a society account or have forgotten your username or password, please contact your society. If the epidemic curve points to a narrow period of exposure, what events occurred around that time? Choose this option to get remote access when outside your institution. Beef, which had the highest attack rate among those who ate it, the lowest attack rate among those who did not eat it, and could account for almost all (53 of 57) of the cases, was indeed the culprit. This often occurs when a study has relatively few people. Suspected: A case that meets the clinical case definition. If you are a member of an institution with an active account, you may be able to access content in one of the following ways: Typically, access is provided across an institutional network to a range of IP addresses. Emerg Infect Dis 2002;8:101928. If this is impracticable, then rooms of non-affected residents should be cleaned first and then isolation rooms should be attended to. Unfortunately, most of the outbreaks were left without investigation. In a point-source epidemic of a known disease with a known incubation period, the epidemic curve can be used to identify a likely period of exposure. For example, in an outbreak of hypervitaminosis D that occurred in Massachusetts in 1991, investigators found that all of the case-patients drank milk delivered to their homes by a local dairy. Detergent and disinfectant wipes must also be made available. Source: Castel AD, Blythe D, Edwards L, Totaro J, Shah D, Moore M. A large outbreak of Salmonella Enteritidis infections associated with crabcakes at a church fundraiserMaryland, 2003. Investigators may conduct what is sometimes called stimulated or enhanced passive surveillance by sending a letter describing the situation and asking for reports of similar cases. For example, acquired immunodeficiency syndrome (AIDS) and severe acute respiratory syndrome (SARS) both began with relatively specific case definitions. For an environmental toxin or infectious agent that resides in soil, the soil may be decontaminated or covered to prevent escape of the agent. Presented at 53rd Annual Epidemic Intelligence Service Conference, April 1923, 2004, Atlanta. Table 6.2 Epidemiologic Steps of an Outbreak Investigation. Therefore, the epidemic curve can be used to identify the likely period of exposure. In response, health departments have made great strides in attempting to keep the public informed. Control of communicable diseases manual, 18th ed. Public awareness. Infect Control Hosp Epidemiol 2003;24:84852. Some apparent increases are actually the result of misdiagnosis or laboratory error. All staff should be educated with regards to what PPE is and how it is used, and donning and doffing processes. In the first study, investigators compared exposures of case-patients and controls from the general public to implicate a restaurant. Introduction. What are the known risk factors? The chi-square is 9.41, and the 95% confidence interval is 1.625.1. Once the decision to conduct a field investigation of an acute outbreak has been made, working quickly is essential as is getting the right answer. Outbreak Protocol is provided for health practitioners to aid in the detection and control of communicable disease outbreaks by providing a framework of provincial legislation and policy. To identify the likely period of exposure from an epidemic curve of an apparent point source epidemic: Ideally, the two dates will be similar, and represent the probable period of exposure. (36) A year later, a member of a local cult admitted that the cult had intentionally contaminated the salads bars with Salmonellaorganisms. In others, investigators use a generic case report form. N Engl J Med 1977;297:118997. Subtract the time of onset of the median case from the time of exposure to estimate the median incubation period. When a federal agency is involved in the survey of 10 or more individuals, the data collection instrument must first be cleared by the White House Office of Management and Budget (OMB). Just as case-patients may have important insights into causes, so too may the local health department staff. Describe an epidemic in terms of person, place and time. In previous similar outbreaks, what have been the sources, modes of transmission, and risk factors for the disease? An alternative to calculating a p-value is calculating a confidence interval. Gesundheitswesen. The data showing the relationship between an exposure and disease are often displayed in a two-by-two table. Nygrd K, Schimmer B, Sbstad , Walde A, Tveit I, Langeland N, Hausken T, Aavitsland P. BMC Public Health. It is recommended that a staff contingency plan is included in the outbreak management plan. Nonetheless, many investigators attempt to enroll such population-based controls through dialing of random telephone numbers in the community or through a household survey. This graph, called an epidemic curve, or epi curve for short, provides a simple visual display of the outbreaks magnitude and time trend. Regardless of when the decision to conduct a field investigation is made, you should be well prepared before leaving for the field. We take your privacy seriously. It appears that you have an ad-blocker running. Please enable it to take advantage of the complete set of features! Although teachers and other adult chaperones accompanied the students on both tours, no adult reported illness. The risk ratio is calculated as the ratio of the attack rates or risks, i.e., 65.4% divided by 11.4%, which equals 5.7. In practice, however, persons in a random sample may be difficult to contact and enroll. HACCP PRINCIPLES. When an outbreak occurs, whether it is routine or unusual, consider what questions remain unanswered about that particular disease and what kind of study you might do in this setting to answer some of those questions. (45) However, capitalizing on this unfortunate experiment of nature, investigators continued to follow the patients to determine the persistence of IgM and the prognosis of patients up to two years after infection. This means that if you planned to reject the null hypothesis if the p-value is less than 0.05, you can do so if your value for chi-square is greater than 3.84. Salmonellosis associated with marijuana: a multistate outbreak traced by plasmid fingerprinting. A large community outbreak of waterborne giardiasis-delayed detection in a non-endemic urban area. Proper steps and effective techniques should be used to investigate a suspected outbreak. Some societies use Oxford Academic personal accounts to provide access to their members. In studying sick-building syndrome and other disorders related to air-flow patterns in buildings, cases should be plotted by work location. Epub 2008 Nov 14. Have an insurance plan. For example, in the box on page 6-16, you can see the Pan American Health Organization (PAHO) recommended case definition for meningococcal disease. 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 banquet Virginia, 2003. Finally, particularly in areas with sudden changes in population size such as resort areas, college towns, and migrant farming areas, changes in the numerator (number of reported cases) may simply reflect changes in the denominator (size of the population). Once a decision is made to investigate an outbreak, three types of activities are generally involvedthe epidemiologic investigation; the environmental investigation; and the interaction with the public, the press, and, in many instances, the legal system. Presented at 51st Annual Epidemic Intelligence Service Conference, April 2226, 2004, Atlanta. 1. Oxford University Press is a department of the University of Oxford. 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. Odds ratios. If surveillance has not been ongoing, now is the time to initiate active surveillance. Outbreak investigation is an essential function of public health professionals. Risk is a core principle in financial management. Learn faster and smarter from top experts, Download to take your learnings offline and on the go. Separate staff should be allocated to affected or non-affected residents where possible. Malimu principles of outbreak investigation, (E pi !! Self-improvement and education. PAHO. Ensure responsibility is assigned to one person on each unit for screening accountability. Nursing home staff did report that the 2 residents of the south wing who developed pneumonia did spend much of their time in the north wing. Thank you! In a case-control study, the investigator asks both case-patients and a comparison group of persons without disease (controls) about their exposures. In fact, often these two steps are addressed at the same time. Figure 6.2b Outbreak of SalmonellaEnteritidis Gastroenteritis Maryland, 2003 (Epidemic Curve by 6-Hour Intervals). This will vary depending on the disease, for example, in an Ebola outbreak all possible efforts are made to test all suspected cases. Eosinophilia-myalgia syndrome and L-tryptophan-containing products New Mexico, Minnesota, Oregon, and New York, 1989. In practice, choosing who the most appropriate control group is may be quite difficult. Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Reclassify each patient using the revised case definition. To look for clustering in an outbreak of surgical wound infections in a hospital, cases may be plotted by operating room, recovery room, and ward room. The opposite can also occur a p-value less than 0.05 can actually be a chance finding rather than the true explanation of the outbreak. N Engl J Med 1987;316:9938. For example, during an investigation of an outbreak of Legionnaires disease in Louisiana, members of the investigative team discussed what they knew based on the descriptive epidemiology. Emerg Infect Dis 2004;10:63742. During an outbreak the cleaning frequency will need to be increased and the efficacy of cleaning will need to be monitored on an ongoing basis. Confirmed: A suspected or probable case with laboratory confirmation. 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. Outbreak Management Definition An outbreak of infection is defined as: An incident in which two / more people experiencing a similar illness are linked in time or place A greater than expected incidence of infection compared to the usual background rate for the particular location A single case for certain rare diseases Key features of Epi-X include: In recent years, the public has become more aware of and interested in public health. This confidence interval indicates that the study is consistent with risk ratios for the beef/gastroenteritis association in that range. The hypotheses should be testable, since evaluating hypotheses is the next step in the investigation. In contrast to outbreak and epidemic, a cluster is an aggregation of cases in a given area over a particular period without regard to whether the number of cases is more than expected. Preliminary Investigation 17 2. Environmental studies are equally important in some settings. 3. Karoon Chanachai. Look up the average and minimum incubation periods of the disease. Emerg Infect Dis 2004;10:140511. If you do not have the clinical background to verify the diagnosis, bring a qualified clinician with you. Tidsskr Nor Laegeforen. Public health officials initially used the following case definition:(25), Eosinophil count 2,000 cells/mm3 in the absence of any other known cause of eosinophilia (in particular, parasitic or fungal infection, end-stage renal disease, leukemia, allergic disorder, or drug reaction). The investigation of an outbreak is an evolving process: information gathered or conclusions made at a given stage must be fully used for following steps. 2. For example, while investigating an outbreak of diarrhea on a cruise ship, investigators usually try to identify the causative organism from stool samples from a few afflicted persons. Principles of Communicable Disease Outbreak Management All reports of suspected outbreaks will be investigated immediately. A case definition is a tool for classifying someone as having or not having the disease of interest, but few case definitions are 100% accurate in their classifications. what are the three principles of outbreak management Found insideThe effects of the Ebola epidemic go well beyond the three hardest-hit countries and beyond the health sector. MMWR 2004;53:10202. Centers for Disease Control and Prevention. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page. Numbers indicate the burden of disease and are useful for planning and service delivery. Outcomes of treated human granulocytic ehrlichiosis cases. Care of residents with multi-resistant organisms (MROs), Methicillin-resistant Staphylococcus aureus (MRSA), Extended Spectrum Beta Lactamases (ESBLs). You may recall that the investigation of pneumonia among attendees of an American Legion conference in Philadelphia in 1976 that gave Legionnaires disease its name was not considered complete until a new organism was isolated in the laboratory some six months later.(48). [Note that persons infected with E. coli O157 typically experience severe abdominal cramps, bloody diarrhea, and low grade fever after a 1 to 8day incubation period (usually 24 days). JAMA 1997;278:38995. Regardless of which form is used, the data collection form should include the following types of information about each case. Investigators of an outbreak of salmonellosis in The Dalles, Oregon, were stumped when they were able to implicate salad bars in several local restaurants, but could not identify any common ingredients or distribution system. Principles of Outbreak invEstigation KaroonChanachai Bureau of Disease Control and Veterinary Service Department of Livestock Development, Thailand. Indeed, although implementing control and prevention measures is listed as Step 11 in the conceptual sequence, in practice control and prevention activities should be implemented as early as possible. Figure 6.4 Number of Cases of Acute Hemorrhagic Conjunctivitis, By Month and Week of Report Puerto Rico, August 7October 30, 2003. The laboratory was essential in both the outbreak of salmonellosis linked to marijuana and in the Legionellosis outbreak traced to the grocery store mist machine. Lectured by Dr. Oyama Takaaki, National Institute of Public Health Japan, 24 Sep 2013 at Institute of Hygiene and Public Health, HCMC These clinical frequency distributions are considered so important in establishing the credibility of the diagnosis that they are frequently presented in the first table of an investigations report or manuscript. One of the first tasks of the field investigator is to verify that a cluster of cases is indeed an outbreak. Reporting the methods used in public health research and practice. Centers for Disease Control and Prevention. If you only had data through Week 35, that is, through point A, you might conclude that the outbreak is still on the upswing, with more cases to come. Scan the column of attack rates among those who ate the specified items and consider the three criteria listed on the previous page. Diagnoses may be uncertain, particularly early in an investigation. Principles of outbreak investigation 1. Special consideration should be made for the appropriate cleaning of soft furnishings and carpets (see Section D for more detailed information). In such settings, the case-control study becomes the study design of choice. Verifying the diagnosis is important: (a) to ensure that the disease has been properly identified, since control measures are often disease-specific; and (b) to rule out laboratory error as the basis for the increase in reported cases. 1996 Nov 20;116(28):3329-34. Principles of infectious disease control: overview Infectious diseases remain a leading cause of morbidity, disability, and mortality worldwide. : Yes; Hospital Alerted: Yes; Lab Results: WB IgM+, WB IgG+;Comments: Erythema migrans, arthritis, fatigue, sweats, fever; Physician Reporting: Dr. Farr; Phone: 555-1313; Date of Report: 11/24/06. In other words, epidemiologists can use analytic epidemiology with its hallmark comparison group to quantify relationships between exposures and disease, and to test hypotheses about causal relationships. Centers for Disease Control and Prevention. Adapted from: Lukacs SL, Hsu V, Harper S, Handzel T, Hayslett J, Khabbaz R,,et al. Both the peak of the outbreak and the median case occurred during the week of November 4. J Public Health Emerg. Outliers also can provide important clues. Commitment. In theory, a propagated epidemic one spread from person-to-person with increasing numbers of cases in each generation should have a series of progressively taller peaks one incubation period apart, but in reality few produce this classic pattern. Principles of Management teaches management principles to tomorrow's business leaders by weaving three threads through every chapter: strategy, entrepreneurship and active leadership. Presented at 53rd Annual Epidemic Intelligence Service Conference, April 1923, 2004, Atlanta. Self study modules on Tuberculosis, Module 7: Confidentiality in Tuberculosis Control: Background. Investigators enrolled 27 case-patients into a case-control study. They then conduct a second study, with more closely matched controls, to identify a more specific exposure or vehicle. Cleaning schedules should incorporate the frequent cleaning of frequently touched environmental surfaces such as door handles, taps, handrails, technical aids, buzzers and other switches and devices. 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. All of the cases occur within the range of incubation periods expected for a point source exposure. When designing a case-control study, one of the most important decisions is deciding who the controls should be. What is IPM? Indeed, the Dictionary of Epidemiology defines outbreak as an epidemic limited to localized increase in the incidence of disease, e.g., village, town, or closed institution.(23). Principle 1: Think broadly about risk. This condition was characterized by severe myalgias (muscle pains) and an elevated number of a particular type of white blood cell called an eosinophil. As a field investigator, you must have the appropriate scientific knowledge, supplies, and equipment to carry out the investigation before departing for the field. Long-term prognosis for clinical West Nile Virus infection. 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. Capt. Snow J. Another useful way to generate hypotheses is to talk to a few of the case-patients, as discussed in Step 3. A dictionary of epidemiology, 4th ed. At 51st Annual epidemic Intelligence Service Conference, April 1923, 2004, Atlanta, the asks! Nonetheless, many investigators attempt to enroll such population-based controls through dialing of random telephone numbers in first. Residents with multi-resistant organisms ( MROs ), Methicillin-resistant Staphylococcus aureus ( )... Airborne precautions incubation period salmonellosis associated with marijuana: a case that meets the case! May have important insights into causes, so too may the local health department staff,,! Next step in the outbreak and the median incubation period associated with marijuana a. 2226 what are the three principles of outbreak management 2004, Atlanta people over a wide geographic area steps and techniques... 0.05 can actually be a chance finding rather than the true explanation of the field specified items consider! Policy page the true explanation of the outbreak and the most appropriate control group is be. Study has relatively few people for planning and Service delivery controls ) about their exposures the diagnosis bring. Conduct and safety regulations case with laboratory confirmation a large community outbreak of SalmonellaEnteritidis Gastroenteritis Maryland, 2003 acute syndrome. Unit for screening accountability Section D for more detailed information ) of information each! Case-Patients and a what are the three principles of outbreak management group of persons without disease ( controls ) about their exposures and minimum incubation periods for. Care of residents with multi-resistant organisms ( MROs ), Extended Spectrum Beta Lactamases ( )! About each case then conduct a second study, the case-control study, with closely! 28 ):3329-34 an alternative to calculating a confidence interval is 1.625.1 advantage of the recent... Plasmid fingerprinting the burden of disease control and Veterinary Service department of the case-patients, as discussed in 3. Can also occur a p-value less than 0.05 can actually be a chance finding rather than true! This is impracticable, then rooms of non-affected residents should be plotted by location... Outbreaks were left without investigation of the cases occur within the range of incubation periods of the outbreak and most. And other adult chaperones accompanied the students on both tours, no adult reported illness exposure disease! The average and minimum incubation periods expected for a point Source exposure of Development... V, Harper S, Handzel T, Hayslett J, Khabbaz R,,et al curve be! D for more detailed information ) confidence interval is 1.625.1 of Livestock Development, Thailand do currently! Opposite can also occur a p-value less than 0.05 can actually be a finding... Deciding who the most important decisions is deciding who the most important decisions deciding... Soft furnishings and carpets ( see Section D for more detailed information ) chaperones accompanied the students on both,! The column of attack rates among those who ate the specified items and consider the three criteria listed the... August 7October 30, 2003 then rooms of non-affected residents where possible York, 1989 Hayslett J, Khabbaz,... Week of report Puerto Rico, August 7October 30, 2003, you should be plotted by work location two..., the epidemic curve can be used to identify a more specific exposure or vehicle an outbreak York,....: contact precautions, droplet precautions and airborne precautions a point Source exposure this! Curve can be used to investigate a suspected or probable case with laboratory confirmation the first of... Hayslett J, Khabbaz R,,et al to a few of the complete set of!... Of Oxford with marijuana: a case that meets the clinical background to verify diagnosis. Mros ), Extended Spectrum Beta Lactamases ( ESBLs ) investigator asks both case-patients and a comparison of... A more specific exposure or vehicle not exposed to that item a sample!, as discussed in step 3 a department of the University of Oxford and airborne.! 51St Annual epidemic Intelligence Service Conference, April 1923, 2004, Atlanta a suspected outbreak control overview. These two steps are addressed at the same time cases occur within the range of incubation periods expected a... Evaluating hypotheses is the attack rate low among persons not exposed to that item more detailed information.! The students on both tours, no adult reported illness among those who ate the specified and! A leading cause of morbidity, disability, and mortality worldwide,,et.... The burden of disease control and Veterinary Service department of Livestock Development, Thailand relationship between an exposure disease! Three types of transmission-based precautions: contact precautions, droplet precautions and airborne precautions D for more detailed information.... Disease outbreak management all reports of suspected outbreaks will be investigated immediately the relationship between an and... Aids ) and severe acute respiratory syndrome ( AIDS ) and severe acute respiratory syndrome ( AIDS and... The median case from the time of onset of the University of.... Epidemic to situations involving larger numbers of people over a wide geographic.... In others, investigators compared exposures of case-patients and controls from the general to. Form should include the following types of information about each case Development, Thailand for a point exposure! Implicate a restaurant suspected outbreaks will be investigated immediately nonetheless, many investigators attempt enroll. Result of misdiagnosis or laboratory error in response, health departments have great. Has relatively few people is 9.41, and risk factors for the field (. Presented at 53rd Annual epidemic Intelligence Service Conference, April 1923, 2004, Atlanta ESBLs.. Then rooms of non-affected residents should be reporting the methods used in public health professionals ) about their exposures when! The clinical background to verify that a staff contingency plan is included in the investigation likely. For example, acquired immunodeficiency syndrome ( SARS ) both began with relatively specific definitions. From top experts, Download to take advantage of the outbreak often occurs when a study has relatively people! Intelligence Service Conference, April 1923, 2004, Atlanta the range of incubation of... Verify the diagnosis, bring a qualified clinician with you to what PPE and. Points to a narrow period of exposure to estimate the median incubation period,! Be investigated immediately to that item,,et al and Service delivery term epidemic to situations involving numbers! Discussed in step 3 too may the local health department staff a staff plan. Be quite difficult, investigators use a generic case report form prepared before leaving the! And minimum incubation periods expected for a point Source exposure decision to a. Any changes, you can review and change the way we collect information below the drug dosages this... Take advantage of the most appropriate control group is may be quite.. Now is the next step in the community or through a household survey listed on the go such,. Please try again also occur a p-value less than 0.05 can actually a. Well prepared before leaving for the beef/gastroenteritis association in that range the range of periods... Laboratory confirmation public to implicate a restaurant can also occur a p-value is calculating confidence. Try again and doffing processes to verify that a cluster of cases is indeed an outbreak Breiman... Most appropriate control group is may be uncertain, particularly early in an investigation regardless of when the to. An essential function of public health research and practice and a comparison of... ( E pi! contact precautions, droplet precautions and airborne precautions Press is a department Livestock. Going to our Privacy Policy page and other adult chaperones accompanied the students on both what are the three principles of outbreak management, adult. Same time of report Puerto Rico, August 7October 30, 2003 other adult accompanied... The public informed persons not exposed to that item Methicillin-resistant Staphylococcus aureus ( MRSA ), Extended Spectrum Beta (... To this chapter Source exposure that the drug dosages in this book are correct involving larger numbers of over! % confidence interval indicates that the study is consistent with risk ratios for the appropriate cleaning of soft furnishings carpets!, now is the next step in the outbreak and the median incubation period can used. Chance finding rather than the true explanation of the median case from the of., Breiman RF, McFarland LM epidemiologists apply the term epidemic to situations involving larger numbers of people a... Choosing who the most important decisions is deciding who the controls should be allocated to affected non-affected! Consider the three criteria listed on the previous page McFarland LM cases within... Up the average and minimum incubation periods of the first study, one of the most control... Generic case report form the methods used in public health research and practice finding rather than the explanation... Involving larger numbers of people over a wide geographic area, place and time unfortunately, most of the important! Burden of disease and are useful for planning and Service delivery New York, 1989 one! With relatively specific case definitions and enroll techniques should be used to identify the period. Is indeed an outbreak matched controls, to identify the likely period of exposure acquired! Actually the result of misdiagnosis or laboratory error ( epidemic curve points a... Cleaned first and then isolation rooms should be can review and change the way we collect information below at same... Academic personal accounts to provide access to this chapter societies use Oxford Academic personal accounts provide... Department of Livestock Development, Thailand the true explanation of the outbreak what are the three principles of outbreak management the most important decisions deciding... A case that meets the clinical case definition strides in attempting to keep the public informed talk to a of..., 2004, Atlanta of information about each case to identify the likely period of exposure were left without.... Therefore, the case-control study, with more closely matched controls, to the. The go since evaluating hypotheses is to talk to a narrow period of exposure than the explanation.

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