MPH504 Module 2 SLP: Measuring Health and Disease

Please answer these questions:
1 What are the advantages and disadvantages of the case definition?
2 Describe and compare the age and gender distribution of E. coli O157:H7 cases from this outbreak and those reported from U.S. FoodNet sites in 1997.
3 What kinds of questions would you ask in the hypothesis-generating interviews?
4 Given your knowledge about E. coli O157:H7, the descriptive epidemiology of the initial cases, and the results of hypothesis-generating interviews, outline the information available at this point on the source of the outbreak and mode of transmission
SLP Assignment Expectations
Length: SLP assignments should be at least 2 pages (500 words) in length.
References: At least two references must be included from academic sources (e.g. peer-reviewed journal articles). Required readings are included. Quoted material should not exceed 10% of the total paper (since the focus of these assignments is critical thinking). Use your own words and build on the ideas of others. When material is copied verbatim from external sources, it MUST be enclosed in quotes. The references should be cited within the text and also listed at the end of the assignment in the References section (APA format recommended).
Organization: Subheadings should be used to organize your paper according to question
Format: APA format is recommended for this assignment. See Syllabus page for more information on APA format.
Grammar and Spelling: While no points are deducted, assignments are expected to adhere to standards guidelines of grammar, spelling, punctuation, and sentence syntax. Points may be deducted if grammar and spelling impact clarity.
The following items will be assessed in particular:
1 Achievement of learning objectives for SLP assignment
2 Relevance (e.g. all content is connected to the question)
3 Precision (e.g. specific question is addressed. Statements, facts, and statistics are specific and accurate).
4 Depth of discussion (e.g. present and integrate points that lead to deeper issues)
5 Breadth (e.g. multiple perspectives and references, multiple issues/factors considered)
6 Evidence (e.g. points are well-supported with facts, statistics and references)
7 Logic (e.g. presented discussion makes sense, conclusions are logically supported by premises, statements, or factual information)
8 Clarity (e.g. writing is concise, understandable, and contains sufficient detail or examples)
Objectivity (e.g. avoid use of first person and subjective bias)
Module 2 – Descriptive Epidemiology and Hypothesis Generation
The incubation period for E. coli O157:H7 ranges from 3-8 days with a median of 3-4 days. The infection often causes severe bloody diarrhea and abdominal cramps, but can also cause a nonbloody diarrhea or result in no symptoms. In some persons, particularly children under 5 years of age and the elderly, the infection can cause a complication called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. About 2-7% of infections lead to this complication.
For this outbreak investigation, a case was defined as diarrhea (at least 3 loose bowel movements a day) and/or abdominal cramps in a resident of the state with onset of symptoms between June 15 and July 15 and a stool culture yielding E.coli O157:H7 with the outbreak strain PFGE pattern.
Of the initial 38 persons who met the case definition, 26 (68%) were female with amedian age of 31 years. (Table 1)
Table1. Age group and gender distribution for persons with E. coli O157:H7 infection and the outbreak PFGE pattern, June 15 – July 15, 1997. (N=38)
Age group (years) Gender
Male Female
0-9 2 (17%)* 2 (8%) 4 (11%)
10-19 2 (17%) 3 (12%) 5 (13%)
20-39 3 (25%) 9 (35%) 12 (32%)
40-59 2 (17%) 8 (31%) 10 (26%)
60+ 3 (25%) 4 (15%) 7 (18%)
TOTAL 12 (101%) 26 (101%) 38 (100%)
percentages refer to column totals.
The 38 cases of E. coli O157:H7 infection meeting the investigation case definition were reported from 10 counties. On set of illness occurred from mid-June to mid-July, peaking on June 22.
From July 16 – 19, hypothesis-generating interviews were undertaken with seven patients. These patients lived in four different counties and ranged in age from 5-69 years. Three of the patients were female.
Hypothesis-generating interviews revealed that most cases had consumed lettuce and alfalfa sprouts in the week before they became ill. No single restaurant or social event was identified in common.
APPENDIX 1. Distribution of E. coli O 157:H7 cases reported to FoodNetSites
by age group and gender, United States, 1997. (N=340)
Age group (years) Gender
Male Female
0-<1 5 (3%) 5 (3%) 10 (3%)
1-9 77 (48%) 77 (43%) 154 (45%)
10-19 36 (22%) 18 (10%) 54 (16%)
20-29 10 (6%) 20 (11%) 30 (9%)
30-39 6 (4%) 12 (7%) 18 (5%)
40-49 7 (4%) 5 (3%) 12 (4%)
50-59 7 (4%) 17 (10%) 24 (7%)
60+ 14 (9%) 24 (13%) 38 (11%)
TOTAL 162 (100%) 178 (100%) 340 (100%)
*Foodborne Diseases Active Surveillance Network (FoodNet) is a collaborative project between CDC, the U.S. Department of Agriculture (USDA), the Food and Drug Administration (FDA), and selected state and local health departments. In 1997, FoodNet conducted population based active surveillance for confirmed cases of Campylobacter, Escherichia coli O157, Listeria,Salmonella, Shigella, Vibrio, and Yersinia infectionsin Minnesota, Oregon, and selected counties in California, Connecticut, and Georgia (total population: 16.1 million).
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