Investigation 21 Global Population Trends Answer Key.zip
b68026692e An intermittent common-source epidemic (in which exposure to the causative agent is sporadic over time) usually produces an irregularly jagged epidemic curve reflecting the intermittence and duration of exposure and the number of persons exposed. They are often helpful in explaining why an outbreak occurred. Method for calculating population attributable risk percent: ( ARP ARU )ARP ARP = Attack rate (risk) in total population ARU = Attack rate (risk) in unexposed group Considering the third criterion listed earlier, notice that almost all (53 out of 57) of the cases could be accounted for by the beef. This information can be found on disease fact sheets available on the Internet or in the Control of Communicable Diseases Manual.(29)Identify the peak of the outbreak or the median case and count back on the x-axis one average incubation period. If the epidemic curve points to a narrow period of exposure, what events occurred around that time? Why do the people living in one particular area have the highest attack rate? Why are some groups with particular age, sex, or other person characteristics at greater risk than other groups with different person characteristics? Such questions about the data may lead to hypotheses that can be tested by appropriate analytic techniques. Type A Clostridium botulinum was then identified from a pan of leftover sauted onions used to make only that particular sandwich.(44)Finally, recall that one reason to investigate outbreaks is research. Interruption of direct transmission may be accomplished by isolation of someone with infection, or counseling persons to avoid the specific type of contact associated with transmission. In studying "sick-building syndrome" and other disorders related to air-flow patterns in buildings, cases should be plotted by work location. Flourescein dye poured into the bathroom of the dorm found its way into the well water, revealing cross-contamination.
Numbers indicate the burden of disease and are useful for planning and service delivery. Presented at 53rd Annual Epidemic Intelligence Service Conference, April 1923, 2004, Atlanta.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. Note that while this approach is typical in the United States, some countries prefer to acquire laboratory samples from every affected person, and only those with a positive laboratory test are counted as true cases.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. A steamship full of trouble: an outbreak of Salmonella Typhimurium DT 104 gastroenteritis at a holiday banquetVirginia, 2003. Some clusters turn out to be true outbreaks with a common cause, some are sporadic and unrelated cases of the same disease, and others are unrelated cases of similar but unrelated diseases.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. If the control group is systematically different from the case group in certain ways, a true association between exposure and disease may be missed or a spurious association may be observed between a non-causal exposure and disease. Finally, laboratorians were able to culture E. More commonly, officials discover an increase in the number of cases of a particular disease and then decide that a field investigation is warranted. 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.In practice, choosing who the most appropriate control group is may be quite difficult.