Science Olympiad Student Center



centertopScience OlympiadInvitational CompetitionFayetteville Manlius High SchoolDec 17 2016Disease DetectivesScience OlympiadInvitational CompetitionFayetteville Manlius High SchoolDec 17 2016Disease DetectivesSchool ______________________________________________Student name _____________________________________________Student name _____________________________________________Part 1. Multiple ChoiceEpidemiology would include which of the following activities? A. Describing the demographic characteristics of persons with acute aflatoxin poisoning in District A B. Prescribing an antibiotic to treat a patient with community-acquired methicillin-resistant Staphylococcus aureus infection C. Comparing the family history, amount of exercise, and eating habits of those with and without newly diagnosed diabetes D. Recommending that a restaurant be closed after implicating it as the source of a hepatitis A outbreakWhich of the following is NOT a goal of epidemiology?To discover the agent, host, and environmental factors that affect healthTo determine the relative importance of causes of illness, disability, and deathTo identify those segments of the population that have the greatest risk from specific causes of ill healthTo evaluate the effectiveness of health programs and services in improving population healthTo provide clinical treatment for individuals and populations that experience disease outbreaksOn Day 1 of a technology conference in Camden, NJ 12 presenters who were setting up for their sessions at the Convention Center became ill with flu-like symptoms. During the course of the conference, 16 participants who attended the conference also became ill with the same symptoms.To begin calculating the rate of this outbreak, investigators should first determineThe number of case illnessesThe number of persons who attended the conferenceThe number of days the conference was helda and ba and cObservational studies are conducted in an attempt tomonitor the public health in preparation for a potential outbreakdetermine whether or not an outbreak has occurreddiscover associations between an exposure or risk factor and a health outcometest the investigator’s hypothesis regarding agent, host, illnessevaluate the efficacy of specific public health interventions The hallmark feature of an analytic epidemiologic study is: (Choose one best answer) A. Use of an appropriate comparison group B. Laboratory confirmation of the diagnosis C. Publication in a peer-reviewed journal D. Statistical analysis using logistic regressionSubjects are selected in a cross-sectional study becausethey are members of a certain population at a certain timethey have been identified by their exposure to one or more risk factorsthey have been positively identified as having a disease conditionthey have been positively identified as NOT having a disease conditionc or dA study of individuals who ate at a particular Taco Bell in Atlanta between October 15th and 20th is an example of a cross-sectional studya case-control studya cohort studya experimental studya case reportTo establish the existence of an outbreak, investigators are NOT likely to use data fromsurveys and questionnairestesting samples taken from the environmentnotifications to the health department if cases are observedsocial media: Face-Book, Twitter, Snap-Chat, etc.financial records, legal records, sales recordsA true increase in the incidence of a disease may be attributed toimprovements in diagnostic proceduresoutbreak of a similar disease, misdiagnosed as disease of interestlaboratory erroran antigenic shift that results in a more virulent strain of agentchanges in local reporting proceduresA cohort study differs from a case-control study in that: A. Subjects are enrolled or categorized on the basis of their exposure status in a cohort study but not in a case-control study B. Subjects are asked about their exposure status in a cohort study but not in a case control study C. Cohort studies require many years to conduct, but case-control studies do not D. Cohort studies are conducted to investigate chronic diseases, case-control studies are used for infectious diseasesThe epidemiologic triad of disease causation refers to: (Choose one best answer) A. Agent, host, environmentB. Time, place, person C. Source, mode of transmission, susceptible host D. John Snow, Robert Koch, Kenneth RothmanIn the following table, the total number of persons with the disease is: 322253450The best estimate of the association between wedding cake and illness is:6.17.768.483.791.794.3To study the causes of an outbreak of aflatoxin poisoning in Africa, investigators conducted a case-control study with 40 case-patients and 80 controls. Among the 40 poisoning victims, 32 reported storing their maize inside rather than outside. Among the 80 controls, 20 stored their maize inside. The resulting odds ratio for the association between inside storage of maize and illness is:3.25.212.033.3A number of passengers on a cruise ship from Puerto Rico to the Panama Canal have recently developed a gastrointestinal illness compatible with norovirus (formerly called Norwalk-like virus). Testing for norovirus is not readily available in any nearby island, and the test takes several days even where available. Assuming you are the epidemiologist called on to board the ship and investigate this possible outbreak, your case definition should include, at a minimum: (Choose one best answer) A. Clinical criteria, plus specification of time, place, and person B. Clinical features, plus the exposure(s) you most suspect C. Suspect cases D. The nationally agreed standard case definition for disease reportingPart 2. Fill-in the blankA report form sent to regional health facilities to gather surveillance data should include the following: information about the reporter, information about patients, demographic information, and ______.A sudden rise in the occurrence of a disease is known as a(n) _____.If a disease spreads over a larger area infecting many communities it may be termed a(n) _____. The _____ rate is the number of new cases of a disease divided by the number of individuals at risk.The most common vehicle for botulinum toxin produced by Clostridium botulinium is _______.Houseflies may transfer Shigella from their appendages to a food item. In this mode of transmission the flies are acting as a _____.Base your answer to the next question on the following dataCalculate the relative risk______ associated with eating ice cream and getting ill.Determine the median time and date of onset in the following chart. The U.S. Centers for Disease Control and Prevention (CDC) estimates that 48 million people in the U.S. suffer from foodborne illness each year resulting in 138,000 hospitalizations and 3,000 deaths.Based on these estimates, calculate the prevalence of foodborne illness (per 100,000) in the U.S. in 2015 (July 1st 2015 population 321,418,820). In an epidemic of hepatitis A traced to green onions from a restaurant, 555 cases were identified. Three of the case patients died as a result of their infections. Calculate the case-fatality rate. The next two questions are based on the same outbreak of foodborne illness.Consider an outbreak of shigellosis in which 18 persons in 18 different households all became ill. If the population of the community was 1,000. Calculate the overall attack rate.One incubation period later, 17 persons in the same households as these “primary” cases developed shigellosis. If the 18 households included 86 persons, calculate the secondary attack rate.Consider the outbreak of hepatitis A illustrated by the chart below for the next two questions. The incubation period for hepatitis A ranges from 15 to 50 days (roughly 2 to 7 weeks), with an average incubation period of 28–30 days. Because cases can occur from 15 to 50 days after exposure, all cases from a point source exposure should occur within a span of 50 – 15 = 35 days. True or False? This outbreak is consistent with a single point source exposure.What is the date of onset of the first case?On what date (month/day) is the exposure most likely to have occurred?The table above is called a ___.Construct a two by two table of botulism illness with exposure to chili. Label columns and rows and include data.Construct an epidemic-curve of these data.Part 3. Outbreak InvestigationsDeaths Associated With Bacterial Pathogens Transmitted Commonly Through Food: Foodborne Diseases Active Surveillance Network (FoodNet), 1996–2005 The Journal of Infectious Diseases 2011;204:263–7Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.Background. Foodborne diseases are typically mild and self-limiting but can cause severe illness and death. We describe the epidemiology of deaths associated with bacterial pathogens using data from the Foodborne Diseases Active Surveillance Network (Food-Net) in the United States.Methods. We analyzed Food-Net data from 1996–2005 to determine the numbers and rates of deaths occurring within 7-days of laboratory-confirmation.b AAPMR are given as deaths/1 million peopleRespond to the following questions based on the data in Table 1.What was the most common cause of death from food borne illness in the U.S. from 1996-2005?What percentage of cases are attributed to Campylobacter?What is the ratio of deaths by Salmonella to deaths by Campylobacter?How many people would be expected to die of Listeria infection per 100,000 cases?Approximately how many people died each year from Listeria infection from 1996-2005?( July 1, 2000 N= 282.16 million)Respond to the following questions based on the data in Table 2.What age-specific cohort is most suseptible to death due to food borne illness according to Table 2?Support your answer with data from Table 2.Explain why this cohort is more suseptible to death than the other age-specific groups. Multistate Shigellosis Outbreak and Commercially Prepared Food, United States Shigella infects an estimated 450,000 people annually in the United States and is usually transmitted through person-to-person spread (1,2). During January 18–21, 2000, California, Oregon, and Washington reported 406 cases of drug-resistant gastroenteritis that developed in several persons after they ate a commercially prepared (brand X), five-layered bean dip; stool cultures yielded S. sonnei. A cohort study of an outbreak at a party implicated this dip; five of six ill attendees had eaten brand X dip compared with none of six well attendees (relative risk = 7.0; 95% confidence interval 1.1 to 42.9). On January 21, the manufacturer began a voluntary recall of the bean dip. We conducted a nationwide investigation to determine the magnitude and severity of the outbreak, confirm its source, and identify the mechanism of contamination.An epidemiological investigation to determine the source and mechanism of an outbreak can also be called a(n) (descriptive, analytical) study. Choose one.To detect an outbreak and monitor dangerous diseases, epidemiologists often depend on reports from health agencies. This is known as (passive, active) surveillance. Choose one.Shigella sonnei is a (disease, pathogen, vector). Choose one. Relative risk is a (ratio, proportion, rate). Choose one.Stool cultures that test positive are necessary to identify cases that are laboratory (likely, probable, confirmed). Choose one.Because people are already sick before this study is started, this would be an example of a (retrospective, prospective) cohort study.Relative risk measures the probability that ________ will lead to illness. Inflammation of the stomach and intestines is referred to as ____________.What was the first control measure or intervention in this case?Imagine you are the investigator on this case of toxic bean dip. Consider the steps of your outbreak investigation. Fill-in the four missing steps to complete your investigation.prepare for field workestablish the existence of an outbreak____________________implement control measuresestablish surveillance measurescommunicate findingsThis dip was epidemiologically implicated as the outbreak source through a cohort study and supported by these findings: 1) patients in several states whose only reported common exposure was the dip and who had genetically-matched S. sonnei infections; 2) isolation of S. sonnei from brand X dip; and 3) outbreak termination after the product was recalled.Numerous problems in manufacturing practices were noted at the dip-production facility, which suggests that the contamination occurred there, probably by an infected employee. The evolving epidemiology of foodborne outbreaks reflects changes in the way that food is processed and distributed. The consumer can be educated to cook or wash minimally processed products such as raw meats, eggs, and fresh produce thoroughly before eating. However, in the case of a ready-to-eat product such as this dip, the responsibility to ensure safety of the product before opening rests with the growers, manufacturers, distributors, and retailers. State one intervention that could be implemented to ensure greater safety of our ready-to-eat food.In this outbreak, a drug-resistant, virulent organism was rapidly disseminated through a commercially processed product. Although this outbreak was likely unintentional, it illustrates the vulnerability of the food supply, which is increasingly characterized by centralized production and broad distribution, and the potential for commercially produced food to be used in an act of bioterrorism. Intentional contamination of a ready-to-eat, widely distributed food product with an organism that has a low infectious dose (e.g., Shigella) can cause considerable illness and can be extremely costly in terms of personal, medical, and public health resources. State on intervention that could be implemented to minimize the risk or impact of bioterrorism through our food supply.Carrier Prevalence, Secondary Household Transmission, and Long-Term Shedding in 2 Districts During the Escherichia coli O104:H4 Outbreak in Germany, 2011The Journal of Infectious Diseases 2013;207:432–8Food itemCases No. (%)Non– CasesNo. (%)OR (95% CI)PSprouts31 (60.8)10 (6.3)<.001Cucumber39 (72.2)64 (39.5)<.001Raw tomatoes46 (78.0)80 (49.1)<.001Lettuce41 (71.9)73 (46.2).001Ground meat(beef)18 (38.3)75 (47.5).269Unpasteurized milk products11 (20.4)32 (20)1 (.5–2).953Background. From May through July 2011, Germany experienced a large outbreak of Shiga toxin–producing Escherichia coli (STEC) O104:H4 infection causing 2987 cases of gastroenteritis, 855 cases of hemolytic-uremic syndrome (HUS), and 53 deaths. The outbreak’s epidemic profile, which differed substantially from that of previous outbreaks of E. coli infection, and notification data can be explained to a great extent by the causing vehicle: cases were predominantly adults, with a median age of 46 years, for gastroenteritis, and 42 years, for HUS. Furthermore, cases mostly occurred among women (58% of gastroenteritis cases and 68% of HUS cases). The estimated median incubation period was 8 days (interquartile range, 6– 10 days).Answer the following questions based on the data in Table 1Table 1. Consumption of Food Items Among Cases and Non-Cases and Association With Disease Outcome During the Shiga-toxinProducing Escherichia coli O104:H4 Outbreak in Germany, 2011Calculate the odds ratio (OR) for the raw tomatoes. [You will need to use the (%) to find the total number of cases and non-cases.]According to the data, which food item appears to be the source of infection? Why did cases of infection occur mostly in women (median age 46)?Objective: The aims of this investigation are to identify the prevalence of STEC O104:H4 carriers in households in highly affected areas, the rate of secondary household transmissions, and the duration of long-term shedding (i.e. emission of pathogens from a host’s body which may facilitate spread to new hosts).A case was defined as (1) a notified STEC gastroenteritis or HUS case (hemolytic-uremic syndrome) with serogroup O104 or unknown serogroup and onset of disease after 30 April 2011, residing in the district of Herzogtum Lauenburg or Schleswig-Flensburg, or (2) a symptomatic or asymptomatic STEC O104:H4 infection that was diagnosed during our investigation by detection of STEC O104:H4 in a stool sample. Disease onset was defined as onset of bloody or non-bloody diarrhea, with diarrhea defined as ≥2 loose stools within 24 hours. A person with detection of STEC O104:H4 after symptomatic or asymptomatic infection was considered a carrier.List the 4 parts of a case definition.This study was conducted in 2 parts. First, we screened for STEC O104:H4 carriers in households with ≥2 members that did or did not have reported cases of STEC-associated gastroenteritis or HUS. Screening of households was performed 3–10 weeks after first notification of the outbreak.Is this part of the study descriptive or analytical in nature?Is this part of the study observational or experimental? Is this an ecological or cross-sectional study design?Second, we followed households in which a carrier was identified to determine rates of secondary household transmission and duration of shedding among STEC O104:H4 carriers. Households with ≥1 carrier and ≥1 household member without reported STEC gastroenteritis or HUS prior to and at the time of screening were enrolled in the study. At 14-day intervals, all participants were asked to provide stool samples and information on gastrointestinal symptoms since the last stool sample. At the first follow-up sampling, the questionnaire also contained questions on household and participants' characteristics and hand hygiene practice. Stool sampling continued until all household carriers tested negative for STEC O104:H4. A negative test had to be confirmed by 2 additional STEC O104:H4–negative samples on 2 consecutive days.Which term best describes the study design of part 2 of this investigation?A. retrospective cohort studyB. prospective cohort studyC. randomized control trialD. case-control studyMatch each of the following statements from this investigation (65-69) with the type of error or bias (A-D) that each exemplifies.selection biasB. information biasC. measurement error D. confounding factorsThe small sample size of our study and, therefore, its limited power makes conclusive statements on STEC O104:H4 carrier prevalence and household transmissions difficult. Mainly because of logistic reasons, the targeted interval between consecutive sampling events was not met. Furthermore, contacts in the study population was aware of carrier(s) in the household, and it may have caused behavior (e.g. an increase in hand-washing) that decreased the chance of secondary infection. Response in our study differed between districts, which could be due to differences in recruitment methods. In Schleswig-Flensburg, disease severity of cases may have resulted in a lower response, as this district had the highest reported HUS incidence; compared with an overall HUS incidence of 25% among cases during the outbreak [3], HUS was reported for only 6% of cases in our study population. Stool sampling procedures and transport conditions until arrival at the laboratory may have resulted in lower sensitivity. Results. For part 1, we recruited 57 case households (62 case patients and 93 household contacts) and 36 control households (89 household members). We only detected cases in previously known case households and identified 1 possible adult-to-adult household transmission. For part 2, we followed 14 households and 20 carriers. No secondary household transmission was detected in the follow-up period. In 1 adult carrier, shedding lasted >7 months. However, the median estimated shedding time was 10–14 days (95% confidence interval, 0–33 days). Three carriers showed intermittent shedding.Conclusions. The prevalence of STEC O104:H4 carriers even in highly affected areas appears to be low. Despite prolonged shedding in some patients, secondary adult-to-adult household transmissions seem to be rare events in the post-diarrheal disease phase.With consideration to the findings in this investigation, when do you think a person who has been infected with STEC 0104:H4 should be able to return to work... if they work in the food industry…handling food? ................
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