08NEDXM3 - Name_ New and Emerging Diseases Exam III April...

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Name___________________________ New and Emerging Diseases Exam III April 11, 2008 Due April 18, 2008 5pm! Read this carefully!   Please write your name on the top of  all  pages.  This must be your own  work.  Any similarities in style or structure to another paper will be penalized.  The lectures and  readings indicate the level of detail necessary.  Answers must be specific and complete to receive  full credit.  For the essay questions,  EACH  statement, opinion or conclusion you make  MUST  be  supported by  at least  one piece of evidence.  Unsupported statements, no matter how brilliant,  will not get any credit. I.   “Community-based epidemiologic studies have shown beneficial effects of hand sanitizers.  Hand sanitizers were effective in reducing gastrointestinal illnesses in households, in curbing  absentee rates in elementary schools, and in reducing illnesses in university dormitories.  To  reduce infections in healthcare settings, alcohol-based hand sanitizers are recommended as a  component of hand hygiene.” Waterless hand sanitizers are used more and more as an alternative to handwashing with soap  and water.  However, despite beneficial effects, some evidence indicates that they may  play a role in increasing  outbreaks of bacterial diseases in certain settings. 1a.  Why might these sanitizers increase outbreaks where handwashing with soap and  water does not? Hint: there is no such thing as alcohol resistance. II.   The varieties of  Escherichia coli  that cause diarrhea are classified into pathogenic groups  (pathotypes) according to their virulence determinants. The specific nature of these virulence  determinants imbues each type with the capacity to cause clinical syndromes with distinctive  epidemiologic and pathologic characteristics. EPEC differs from other forms of  E. coli  in that it  typically carries an EPEC adherence factor plasmid (pEAF). This plasmid encodes 1) bundle- forming pili (Bfp), and 2) a transcriptional activator, Per. A subset of EPEC, known as atypical  EPEC, do not carry pEAF and hence do not produce Bfp or Per.  Table 1. Classification of pathogenic Escherichia coli according to virulence-associated determinants Interpretation† Gene or virulence-associated determinant* pCVD432 aggA bfpA eae ipaC stIA ltA ehxA stx1 stx2 EAEC‡ + + Typical EPEC + + Atypical EPEC + EIEC + ETEC‡ + + EHEC§ + + + + STEC not EHEC¶ + +
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*Factors specified by virulence genes: aggA , aggregative fimbria, AAF/I;
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This note was uploaded on 04/16/2008 for the course BIOLOGY NEW AND EM taught by Professor Edwardcluett during the Spring '08 term at Ithaca College.

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08NEDXM3 - Name_ New and Emerging Diseases Exam III April...

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