Lecture21 - 4/8/11 Lecture 21 The Epidemiology and...

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4/8/11 1 Lecture 21 The Epidemiology and Evolution of Neisseria, E. coli, Anthrax and Tyhpoid Neisseria Meningococcal Disease Meningococcal disease is a potentially life-threatening bacterial infection. • Expressed as either: – Meningococcal meningitis, or – Meningococcemia (can result in septicemia) Meningococcal disease was first described in 1805 (by Visseaux) when an outbreak swept through Geneva, Switzerland. The causative agent, Neisseria meningitidis (the meningococcus), was identified in 1887.
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4/8/11 2 Public Health Significance Leading cause of bacterial meningitis in children and young adults in the United States 2,400 to 3,000 cases each year in U.S. 5% to 10% of patients die, typically within 24-48 hours of onset of symptoms. 10 to 20% of survivors of bacterial meningitis may result in brain damage, permanent hearing loss, learning disability or other serious sequelae. • 18-23 years old 1.4 / 100,000 • 18-23 years old not college student 1.4 / 100,000 • Freshmen 1.9 / 100,000 • Freshmen in dorm 5.1 / 100,000 Meningococcal Disease Among Young Adults, United States, 1998-1999 • Bruce et al . JAMA 286 , 688-693 (2001) Highest Frequency of Meningitis is in Sub-Saharan Africa (‘Meningitis Belt’)
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4/8/11 3 N. meningitidis - Meningitis N. gonorrheae - Gonorrhea • Non-motile, Gram negative • Usually diplococci • Aerobic to microaerophilic, fastidious • Fragile Neisseria gonorrheae History: – Known since ~100 AD – Known to be venereal since ~1200 – First cultivated in 1882 Resistance to penicillin is now a problem; antibiotic therapy has not decreased incidence No polysaccharide capsule (therefore direct transmission needed) Gonorrhea may be the most prevalent human bacterial disease – Leading cause of STD in US – >400,000 cases reported yearly – May be over 1 million Limited survival outside host (because of lack of capsule) Transmitted by direct contact Attaches by pili to columnar epithelium: • cervix, urethra, throat, rectum • postpubescent women: genital infection restricted to cervix • vaginal mucosa: squamous not columnar epithelium, cannot colonize squamous Neisseria gonorrheae
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4/8/11 4 Neisseria meningitidis Causes meningitis and septicemia Only natural reservoir: human nasopharyngeal mucosa ~ 10% average nasal carrier rate: – many isolates may be from clones not associated with invasive meningococcal disease – rate may be as high as 90% in some populations Transferred via direct contact or respiratory droplets (kissing, sneezing, coughing on someone, living in close quarters or dormitories sharing eating or drinking utensils, etc.) Temporal peaks in late winter–early spring N. meningitidis Colonization and Invasion Damage to ciliated epithelium increases risk of carriage and invasive disease (smoke, stress, viral infections) Adherence: – mediated by pili, OMPs (‘opacity proteins’)
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Lecture21 - 4/8/11 Lecture 21 The Epidemiology and...

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