chp24 digestive worksheet-1

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BIO208, Lecture #26 Digestive System Infections, Chapter 24 Helicobacter pylori produces urease, an enzyme that is capable of neutralizing the harsh environment of the stomach. Most microbes are unable to grow here but H. pylori can because it is a(n) A. Alkalinophile B. Acidophile C. Neutrophile D. Psychrophile Which of the following are hosts of Salmonella enterica serotype typhi? A. All mammals B. Reptiles C. Humans D. Mammals and reptiles Complete sentences using the word bank. 1. anus 2. goblet cells 3. infection 4. lower GI 5. low pH fluids 6. lysozyme 7. mouth 8. normal biota 9. Peyer’s patches 10. upper GI The GI tract is a long tube, extending from the mouth to the anus , responsible for the delivery of nutrients. The GI tract carries a large amount of normal biota but they inhabit distinct areas of this system. The oral cavity harbors normal microbiota, the rest of the upper GI has few microbes, however the lower GI is inhabited by billions of microbes including Bifidobacterium, Clostridium, Lactobacillus, and Escherichia species. In addition to the normal biota, the GI tract encounters millions of new microorganisms every day, requiring this system to posses a variety of defenses against infection . Various fluids in the GI tract are antimicrobial; the saliva contains lysozyme , the stomach contains low pH fluids , and bile is antimicrobial. Gobelt cells produce mucus and Peyer’s patches secrete IgA antibodies. By detecting the molecules on the surface of a microbe, you can distinguish different serotypes of a species. Why is serotyping particularly important in Salmonella infections and Typhoid fever? A. Salmonella enterica serotype Enteritidis causes mild self-limiting disease but Salmonella enterica serotype Typhimurium requires treatment. B. The serotype determines the disease caused and the treatment needed (if any). C. Salmonella enterica serotype Typhi causes severe systemic disease and some can be asymptomatic carriers. D. All serotypes are capable of causing Typhoid Fever. E. B and C 1

Mary Mallon worked as a cook in New York in the early 20th century. Over seven years, from 1900 to 1907, Mallon worked for a number of different households, unknowingly spreading illness to the people who lived in each one. In 1906, one family hired George Soper, an expert in typhoid fever epidemics, to determine the cause of the illnesses in their household. Eventually, Soper tracked Mallon down and directly linked 22 cases of typhoid fever to her. He discovered that Mallon was a carrier for typhoid but was immune to it herself. Although active carriers had been recognized before, this was the first time that an asymptomatic carrier of infection had been identified. Because she herself had never been ill, Mallon found it difficult to believe she could be the source of the illness. She fled from Soper and the authorities because she did not want to be quarantined or forced to give up her profession. Mallon was eventually caught and kept in an isolation facility in the Bronx, where she remained until 1910, when she soon began working as a cook again. After new cases began to appear that resulted in the death of two individuals, the authorities tracked her down again and returned her to isolation, where she remained for 23 more years until her death in 1938. Epidemiologists were able to trace 51 cases of typhoid fever and three deaths directly to Mallon, who is unflatteringly remembered as “Typhoid Mary.” The Typhoid Mary case has direct correlations in the health-care industry. Consider Kaci Hickox, an American nurse who treated Ebola patients in West Africa during the 2014 epidemic. After returning to the United States, Hickox was quarantined against her will for three days and later found not to have Ebola. Hickox vehemently opposed the quarantine. In an editorial published in the British newspaper The Guardian,6 Hickox argued that quarantining asymptomatic health-care workers who had not tested positive for a disease would not only prevent such individuals from practicing their profession, but discourage others from volunteering to work in disease-ridden areas where health-care workers are desperately needed. 1. What happens when an individual believes they are not a risk, but others believe they are? I feel that public health is more important than your personal freedom and that in order for us to get the issue under control, we need to quarantine. 2. How would you react if you were in Mallon’s shoes and were placed in a quarantine you did not believe was necessary, at the expense of your own freedom and possibly your career? I would be upset because I would feel like my time is being wasted on something that is not necessary but I would eventually come to terms with it and understand that we would not be doing this if public health officials didn’t think it would help. 3. Would it matter if you were definitely infected or not? I would want to know because it would make a difference. Explain in your own words: How does V. cholera cause rapid dehydration? V. cholera causes rapid dehydration because it causes large amounts of electrolytes to be released into the intestine that then results in water being released into the lumen. The releases water is then shed by the host in rice water stools. 2

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