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18 Cards in this Set
- Front
- Back
Cholera Epidemiology
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Epidemic cholera caused by the O-1 (the classic and El Tor biotype forms) and O-139 types
--Others cause diarrheal disease spread through contaminated drinking waterand food, no p2p High Infectious Dose Worldwide distribution: massive human morbidity and mortality. US: Gulf Coast/Travel Associated--> not harbingers of epidemics Periodic epidemics and pandemics frequent attendant of disasters (natural and human-made) Reservoir: 20% of human aSx cariers in endemic regions, zooplankton (1854 John Snow) |
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Cholera Clinical Manifestations
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1-5 days incubation: Colonization of small intestine mucosa WITHOUT change in physical integrity
Cardinal feature : abrupt onset massive watery diarrhea (1 liter /hour) "Rice water” stools Rapid Death from dehydration. electrolyte loss Micro-45-ppt-3 |
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Vibrio cholerae morphology, biochemistry
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nonspore-forming Gram negative facultatively anaerobic vibrio
Oxidase positive Motile, polar flagellum Classified by O antigens: O-1 & O-139 infect humans Micro-45-ppt-6 |
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O-1 Vibrio cholerae
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Classic epidemic cholera
Epidemic-associated biotypes “classic” and “El Tor” El Tor hardier, dominant cause of O-1 serogroup-caused cholera epidemics Both biotypes may be divided into additional epidemic–associated serotypes; [Inaba, Ogawa, Hikojima] No cross-reaction with O-139 Vibrio cholerae Micro-45-pdf-3 |
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O-139 Vibrio cholerae
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Newly recongized cholera agent
O-1 LPS synthesis genes replaced no corss rxn with O-1 V cholera = reinfection Micro-45-pdf-3 |
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Cholera toxin
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AB enterotoxin of Cholera from phage 9kb ctx genes
ctx = filamentous m13 related virus ctx virus receptor endoced by tcp (toxin coregulated pilus) pathogenicity island, VPI, the genome of the filamentous VPI phage B: Binds Surface G1 A: ADP-ribosylates a cAMP regulatory GTP binding protein cAMP levels increase-->hypersecretion-->severe diarrhea ToxR gene/protein senses environment, controls txp and ctx expression best in small intestine with [iron]low. quorum sensing deactivates pilus. Micro-45-ppt-9 |
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VPI phage
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filamentous phage
lysogenic conversion with vibrio cholera-->Vibrio cholerae pathogenicity island tcp gene (toxin coregulated pilus) encodes for both an attachment pilus and for receptors for the CTX Phage CTX Phage (Cholera Toxin) encodes AB endotoxin which produces diarrhea ToxR gene/protein senses environment, controls txp and ctx expression best in small intestine with [iron]low. quorum sensing deactivates pilus. Micro-45-ppt-12 |
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V cholerae Dx
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Direct microscopic examination of stool
Large numbers of vibrio-shaped bacteria present Not easy to observe (despite numbers) -- typically look for motility Culture--grows on most media use for stool cultures Dies in acidic dry environments Best: base, high salt: Thiosulfate citrate bile salts sucrose (TCBS): opaque yellow colonies Rapid agllutination tests, specific antiseras Non-lysogenic V cholerae may cause diarrhea, but not cholera Micro-45-ppt-15 |
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Cholera Treatment
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Mild disease- Oral rehydration solution (ORS) administration, glucose enhances Na uptake
Severe cases- IV Lactated Ringer’s solution until pulse restoration, then oral glucose rehydration solution Antibiotics: Tetracycline. Ciprofloxacin, TMP-SMX Fluid Secretion continues after bacteria gone because Toxin still around Micro-45-pdf-8 |
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Index Case for an Outbreak
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(Index case = first pt.)
Often member of carrier's household (20% of humans in endemic regions are carriers) El Tor O-1 V cholerae survives better than classic O-1 as carrier. Micro-45-ppt-23 |
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Cholera Susceptibility factors
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More severe in blood group O
Acid sensitive: achlorohydria, reduced gastric acidity, reduced gastric retention. Neutralized pH= 10kx reduxn in inoculum micro-pdf-45-10 |
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Cholera Vaccine
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killed organism/toxoidvaccine
Short lived-immunity, with side effects, not fnx vs all endemic strains Travelers should take prophylactic tetracycline Not needed mostly because high infectious dose if hygiene good Live attenuated strains not good since toxicity from lysogenic conversion Micro-45-pdf-10 |
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Preventing Cholera
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Travelers should take prophylactic tetracycline
Not needed mostly because high infectious dose if hygiene good Proper Control of Sewage Micro-45-ppt-29 |
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Most common cause of bacterial food-borne illness in Japan
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V. parahaemolyticus:
Gastroenteritis to a mild cholera-like illness Micro-45-pdf-11 |
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V. parahaemolyticus
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self-limiting disease gastroenteritis to a mild cholera-like illness
normal inhabitant of coastal ocean and estuary waters Consumption of raw or undercooked shellfish has been a recurrent source of human infection. Summer disease, World-wide distribution, endemic in Japan, US Gulf Coast Oxidase positive, will form green colonies on TCBS agar Micro-45-pdf-11 |
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V. vulnificus
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coastal marine and estuary waters
associated with oysters, seawater with oyesters more common when warm (Summer Disease) particularly virulent: wound infections, acute-self-limiting diarrhea, and fatal septicemia (raw oyesters + liver dysfunx/underlying debilitation--> bullous skin lesions, vomiting, shock, tx with tetracycline) Micro-45-ppt-35 |
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37Recognizing VibrioInfections
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1% sodium chloride is required for the growth of this microbe
Sucrose non-fermenters: Usually forms green colonies on TCBS agar (though V Cholera = yellow) If a vibrio suspected, request TCBS agar or vibrio isolation favorable agar. Probably significantly under-diagnosed Micro-45-ppt-37 |
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V Cholera
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related to El Nino
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