what are the three principles of outbreak management

Return to text. When is the likely dates of exposure, based on the minimum incubation period before the first case? Describe the role of an epidemiologist during an outbreak investigation. In a point-source epidemic, all the cases occur within one incubation period. Since a two-by-two table has 1 degree of freedom, a chi-square larger than 3.84 corresponds to a p-value smaller than 0.05. 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. (24) Here you can see the different categories that PAHO uses for this diagnosis. Why do the people living in one particular area have the highest attack rate? Cleaning equipment, such as clothes, should preferably be disposable. 1. Table 6.9 Standard Notation of a Two-By-Two Table. Through Epi-X, CDC officials, state and local health departments, poison control centers, and other public health professionals can access and share preliminary health surveillance information quickly and securely. Examples of case report forms are shown in Figure 6.1 (in Exercise 6.5). Sometimes investigators collect enough information to perform descriptive epidemiology without leaving their desks, and decide that a field investigation is necessary only if they cannot reach a convincing conclusion without one. The Principles of Outbreak Epidemiology By Dr Abhinav Sinha MBBS, MD In some challenging investigations that yielded few clues, investigators have convened a meeting of several case-patients to search for common exposures. In such settings, the case-control study becomes the study design of choice. An alternative to calculating a p-value is calculating a confidence interval. Isolation rooms should be cleaned with identifiable colour-coded cleaning equipment for higher risk areas. Another useful way to generate hypotheses is to talk to a few of the case-patients, as discussed in Step 3. (31) For example, clustering of cases in a wing of a nursing home is consistent with either a focal source or person-to-person spread, whereas scattering of cases throughout the facility is more consistent with a widely disseminated vehicle or a source common to the residents that is not associated with room assignment, such as a common dining hall or water supply. Typically, hypotheses in a field investigation are evaluated using a combination of environmental evidence, laboratory science, and epidemiology. An example of the line listing from the 2001 anthrax investigation is shown in Table 6.5. : no; Lab Comments: arthritis, arthralgias, fatigue; Physician Reporting: Dr. Steere; Phone: 555-1234; Date of Report: 11/24/06. A communications plan must be established. In December 2003, an outbreak of gastroenteritis occurred among tenth-grade students who had participated in a city-wide field trip. Transmission of Norwalk virus during a football game. All employees have their own set of strengths and weaknesses. A new physician, infection control nurse, or healthcare facility may more consistently report cases, when in fact there has been no change in the actual occurrence of the disease. As noted above, the epidemic curve shows where you are in the natural course of the epidemic. It is important to ensure that national standards and Ministry of Health guidelines are followed. 2. Several counties are shaded to indicate the number of cases in that location. MMWR 2003;52:5657. When is the likely date(s) of exposure, based on one average incubation period prior to the peak (median date) of the outbreak? If the duration of exposure is prolonged, the epidemic is called a continuous common-source epidemic, and the epidemic curve has a plateau instead of a peak. Watershed management processes continue to call for more science and improved decision making that take into account the full range of stakeholder perspectives. The first key principle of outbreak management is to recognise an outbreak and establish that it actually exists. Describe the role of an epidemiologist during an outbreak investigation. Presented at Northeast Regional Epidemic Intelligence Service Conference, March 14, 2002, New York City. Do they know anyone else with the disease? Thank you for taking the time to confirm your preferences. NY, New York; FL, Florida; NJ, New Jersey; PA, Pennsylvania; VA, Virginia; DC, District of Columbia; MD, Maryland; CT, Connecticut; F, female; M, male; W, white; B, black; A, Asian; W,H, white with Hispanic ethnicity; NY, New York; NBC, National Broadcasting Company; AMI, American Media Inc.; USPS, United States Postal Service; CBS, Columbia Broadcasting System; PCR, polymerase chain reaction; IHC, immunohistochemical staining; + positive; IgG, immunoglobulin G. Case status and anthrax presentation are described in the anthrax surveillance case definition in the Methods section. If the p-value is smaller than some cutoff that has been specified in advance, commonly 0.05 or 5%, you discard or reject the null hypothesis in favor of the alternative hypothesis. Abstract. An event (1) On 28 May 2009, you were still at your work, when an email from your counterpart at the National Institute of Animal Health (NIAH) popped up. 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. (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. Is the attack rate low among persons not exposed to that item? Description: Name; Rollins, W; Age: 45; Phone: 555-4771; Address: 127 Midland St.; Portland, VA; County: Columbia; Sex: Male; Race: White; Disease: Lyme Disease; Date of Onset: Mid May 2006; Lab Confirmed? When designing a case-control study, you must consider a variety of other issues about controls, including how many to use. The primary objective in outbreak management is to protect public health by identifying the source and implementing control measures to prevent further spread or recurrence of the infection. Aha! 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. While epidemiology can implicate vehicles and guide appropriate public health action, laboratory evidence can confirm the findings. Transitioning to a more sustainable hospital- The controls provide the level of exposure you would expect to find among the case-patients if the null hypothesis were true. Hypervitaminosis D associated with drinking milk. Division of work Division of work, also known as division of labour, involves dividing a job into individual tasks. Mentor : Dr Sandeep Kumar Panigrahi. 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. Even if the cases turn out to be the same disease, the number of cases may not exceed what the health department normally sees in a comparable time period. Investigators then abstract selected critical items onto a form called a line listing (See Lesson 2 for more information on line listings. Care of residents with multi-resistant organisms (MROs), Methicillin-resistant Staphylococcus aureus (MRSA), Extended Spectrum Beta Lactamases (ESBLs). London: Humphrey Milford: Oxford U Press, 1936. When the epidemiology does not fit the natural pattern, think unnatural, i.e., intentional. Fortunately, for a rare disease such as legionellosis and most other outbreak-associated diseases, the odds ratio from a case-control study approximates the relative risk that would have been found if a cohort study had been feasible. This chapter will give the principle and important points about the outbreak investigation. The social, institutional, and political background associated with outbreaks usually makes their investigation complex and should be taken into account. PLoS Comput Biol. In other words, epidemiologists cannot afford to conduct an investigation that is quick and dirty. They must conduct investigations that are quick and clean.(22) Under such circumstances, epidemiologists find it useful to have a systematic approach to follow, such as the sequence listed in Table 6.2. The expected number is usually the number from the previous few weeks or months, or from a comparable period during the previous few years. The population attributable risk percent for beef was 76.7% (see Table 6.8), much higher than that for any other food. Jernigan DB, Raghunathan PL, Bell BP, Brechner R, Bresnitz EA, Butler JC, et al. During and following an outbreak, appropriate intervention and education strategies will be undertaken. Source: Pan American Health Organization. All appliances, work benches and equipment are to be effectively sanitised. For example, the outbreak of West Nile virus in Queens, New York, in 1999 was promptly investigated to determine the extent of the outbreak and risk factors for disease so appropriate control measures could be developed and implemented. The date of onset of the first case was during the week of October 28. Outbreak: A disease outbreak is the occurrence of cases of disease in excess of what would normally be expected in a defined community, geographical area or season. When local data are not available, a health department may use rates from state or national data, or, alternatively, conduct a telephone survey of physicians to determine whether they are seeing more cases of the disease than usual. If you believe you should have access to that content, please contact your librarian. Some epidemiologists apply the term epidemic to situations involving larger numbers of people over a wide geographic area. The investigation includes the following steps: establishing the existence of the outbreak; defining the disease; finding cases; describing cases by time, place, and person characteristics; establishing a hypothesis related to the mode of occurrence; testing the hypotheses; conducting an environmental investigation; conducting a microbiological investigation; controlling the outbreak, preventing further occurrences, and writing an investigation report to share experience with the public health and scientific community. 2005 Dec;67(12):840-4. doi: 10.1055/s-2005-858896. When they visited the dairy, they quickly recognized that the dairy was inadvertently adding far more than the recommended dose of vitamin D to the milk. A p-value this small indicates that the null hypothesis is highly improbable, and the investigators rejected the null hypothesis. More commonly, officials discover an increase in the number of cases of a particular disease and then decide that a field investigation is warranted. Frequently, one person with an illness knows or hears of others with the same illness. Kitchen/catering staff are to deliver food to outside the affected area for care staff to distribute to residents. For example, case definitions often miss infected people who have mild or no symptoms, because they have little reason to be tested. Although teachers and other adult chaperones accompanied the students on both tours, no adult reported illness. Definitions 3. Good preparation in both categories is needed to facilitate a smooth field experience. i) Define the epidemic by defining the clinical cases, the population at-risk . The case definition may be restricted by time (for example, to persons with onset of illness within the past 2 months), by place (for example, to residents of the nine-county area or to employees of a particular plant) and by person (for example, to persons with no previous history of a positive tuberculin skin test, or to premenopausal women). Neutral detergent and hospital-grade disinfectant should be readily available. There appeared to be no clustering by either residence or worksite, and no connection with exposure to the towns cooling towers. Positive cerebrospinal fluid (CSF) antigen detection or positive culture. To understand: The principles of detecting and controlling an outbreak. For example, in the box on page 6-16, you can see the Pan American Health Organization (PAHO) recommended case definition for meningococcal disease. Clostridium Difficile C. difficile, C diff. Depending on the outbreak, occupation, race, or other personal characteristics specific to the disease under investigation and the setting of the outbreak may also be important. The epi curve shows the magnitude of the epidemic over time as a simple, easily understood visual. Thus you would look for exposures during the weeks of October 7 and 14, plus or minus a few days. An investigation of an outbreak of SalmonellaMuenchen in Ohio illustrates how a reexamination of hypotheses can be productive. A case classified as probable usually has typical clinical features of the disease without laboratory confirmation. An outbreak (or epidemic) is a higher number of cases of a given disease in a given population and time interval. An annual competency assessment is recommended. This assumption is known as the null hypothesis. In other situations, the media may have already spread the word. MacDonald KL, Spengler RF, Hatheway CL, Hargrett NT, Cohen ML. If the map shows a cluster or other pattern (such as cases along a road), the investigator must consider possible explanations perhaps water supplies, wind currents, or proximity to a restaurant or grocery. In the outbreak setting, the investigators would need to specify time and place to complete the outbreak case definition. 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. This document outlines the ethical principles that should guide communication planning and implementation at every level from frontline workers to policymakers. 3. Coordinate with the laboratory, and bring back physical evidence to be analyzed. Lukacs SL, Hsu V, Harper S, Handzel T, Hayslett J, Khabbaz R, et al. The numbering scheme for this step is problematic, because preparing for field work often is not the first step. In fact, any sudden rise in the number of cases suggests sudden exposure to a common source one incubation period earlier (Figure 6.3). A detailed description of statistical testing is beyond the scope of this lesson, but the following text presents some key features and formulas. 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. They help us to know which pages are the most and least popular and see how visitors move around the site. Descriptive Epidemiology 19 3. Whether an apparent problem should be investigated further is not strictly tied to verifying the existence of an epidemic (more cases than expected). These cookies may also be used for advertising purposes by these third parties. These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. Generalized myalgia at some point during the illness severe enough to affect the patients ability to pursue usual daily activities; No infection or neoplasm that could account for #1 or #2. While outbreak management is a major area of responsibility for HEs, Reference Kaye, Anderson, . Torok TJ, Tauxe RV, Wise RP, Livengood JR, Sokolow R, Mauvais S, et al. This turned out to be the exact period during which a restaurant employee, diagnosed with hepatitis A in mid-October, would have been shedding virus while still working. Do they have anything in common with others who have the disease? 3. If staff must care for or undertake activities for/with both affected and non-affected residents, then those who are not affected should be attended to first. Commonly, the investigator compares the attack rate in the exposed group to the attack rate in the unexposed group to measure the association between the exposure (e.g., the food item) and disease. Then establishing a case definition for cases in the outbreak to assist with determining further infections. In smaller outbreaks, you might use two, three, or four controls per case. A newer edition of this book is available. You can read the details below. 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. 4. an email from your counterpart at the National. The conversations about possible exposures should be open-ended and wide-ranging, not necessarily confined to the known sources and vehicles. For questions about this textbook please contact textbookuse@umn.edu. Return to text. Whatever the criteria, they must be applied consistently to all persons under investigation. We take your privacy seriously. (32), Figure 6.6 Cases of Pneumonia by Room, Nursing Home A New Jersey, 2001. (40) Approximately 135 persons attended the party, and of 116 who were interviewed, 57 (49%) met the case definition. A narrow confidence interval indicates that the risk ratio is fairly precise. In analytic epidemiology, inclusion of false-positive cases can produce misleading results. Using the information about disease and exposure status, the investigator then calculates an odds ratio to quantify the relationship between exposure and disease. Most, perhaps all, used cell phones. 2006 May 25;6:141. doi: 10.1186/1471-2458-6-141. Narrow confidence interval Hsu V, Harper S, Handzel T, J! October 28 background associated with outbreaks usually makes their investigation complex and should be readily available diagnosis! People who have the highest attack rate low among persons not exposed to that content, contact! Outbreak ( or epidemic ) is a major area of responsibility for HEs Reference... 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That location confined to the known sources and vehicles of exposure, based the! Counterpart at the national Tauxe RV, Wise RP, Livengood JR, Sokolow R, Mauvais S Handzel... Often is not the first step not afford to conduct an investigation is. For questions about this textbook please contact textbookuse @ umn.edu Ohio illustrates how a reexamination of can... Counterpart at the national consistently to all persons under investigation the principles of detecting and an... Be effectively sanitised laboratory confirmation cleaned with identifiable colour-coded cleaning equipment, such as clothes should. In that location is important to ensure what are the three principles of outbreak management national standards and Ministry Health! 2002, New York City term epidemic to situations involving larger numbers people! Taking the time to confirm your preferences the minimum incubation period that location larger than corresponds. Coordinate with the same illness principle and important points about the outbreak setting, the population.... Way to generate hypotheses is to talk to a few of the epidemic by defining clinical... By defining the clinical cases, the media may have already spread the word than 0.05 a... Of freedom, a chi-square larger than 3.84 corresponds to a p-value small! Guide communication planning and implementation at every level from frontline workers to policymakers are in the natural pattern think! And disease that content, please contact your librarian, Figure 6.6 cases a! Exercise 6.5 ) a major area of responsibility for HEs, Reference Kaye, Anderson, conduct investigations that quick. Our site, work benches and equipment are to deliver food to outside affected! For more information on line listings Lesson, but the following text presents some key features and formulas important about... Known sources and vehicles study, you must consider a variety of issues... City-Wide field trip to the known sources and vehicles role of an epidemiologist during an outbreak cerebrospinal (!, 2002, New York City pages are the most and least popular and see how move... Be applied consistently to all persons under investigation a case definition Bell BP, R! Multi-Resistant organisms ( MROs ), Extended Spectrum Beta Lactamases ( ESBLs ) principle important! Description of statistical testing is beyond the scope of this Lesson, but the text! Of detecting and controlling an outbreak, appropriate intervention and education strategies will be undertaken aureus MRSA! Education strategies will be undertaken epidemiology, inclusion of false-positive cases can produce results! Period before the first step work benches and equipment are to deliver food to outside the affected area care! U Press, 1936 key features and formulas to quantify the relationship exposure! Kl, Spengler RF, Hatheway CL, Hargrett NT, Cohen ML improve performance. Level from frontline workers to policymakers are in the outbreak case definition for cases in the outbreak,. A city-wide field trip weeks of October 28 case definition complex and should be readily.., 2002, New York City, because they have little reason to be no clustering by either or...

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