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31 Cards in this Set
- Front
- Back
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Where did the 7th pandemic start?
What were the dates and times of spread? Name strain in the gulf coast |
SEA - 1961
Africa - 1970 SAmerica - 1991 |
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Name strain in the gulf coast
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El Tor, serotype Inaba endemic in Gulf Coast
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Where and when was Haiti's cholera outbreak?
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Confirmed Oct 19-21, 2010
Nov 16th - Dominican Republic and travelers from Florida |
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What is the serotype in haiti?
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V. cholerae O1 serotype Ogawa
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Describe group O1
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Group O1 associated with profuse, watery diarrhea
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Describe gropu O139
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Group O139 also produces high levels of cholera toxin and a disease similar to group O1
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What are the 2 serotypes
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Ogawa
Inaba |
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What are the 2 biotypes
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Classical and El Tor
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what does the vibrio toxin do?
Describe the toxin |
Toxin affects cellular metabolism, produces a secretory diarrhea
Toxin = 5 binding B subunits, 1 active A subunit |
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What does the toxin subunit do?
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A subunit stimulates adenylate cyclase--> increased levels cAMP--> inhibition of Na/K pump, stiumulation Cl- secretion--> secretory diarrhea
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Name the biotype and strain of cholera in Haiti 2010-2011
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All strains confirmed as toxigenic biotype El Tor, serotype Ogawa, and most strains have similar pattern by pulsed field gel electrophoresis
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How is the strain in Haiti similar to the strains from S.America?
Are they the same as Latin America and Africa/? |
Strain from Haiti is clonal and alterations in the ctxB gene are similar to strains from South Asia (esp. Bangladesh),
distinct from strains from Latin America and Africa |
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what is the spectrum of illness in persons infected with v.cholera o1, biotype el tor?
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75% asymptomatic
18% mild illness 5%moderate illness 2% severe illness |
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Describe a mild illness of cholera
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Predominance of El Tor infections (7:1)
Occasional loose stools, without significant dehydration Symptoms resolve within one week Low incidence of asymptomatic carriage |
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What are the complications of cholera?
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Metabolic acidosis--due to loss of bicarbonate in the stool; also due to lactic acidosis from poor tissue perfusion and hypovolemic shock; acidosis can mask hypokalemia
Renal Failure--and renal tubular acidosis, due to hypovolemic shock; generally responds rapidly to rehydration Hypoglycemia--more frequent in children; associated with increased mortality, so patients with hypoglycemia require aggressive replacement by either IV or oral route Cardiac arrhythmias--from hypokalemia and acidosis Paralytic ileus--from hypokalemia Seizures--more frequent in children with hypoglycemia Cholera in pregnant women--High rate of fetal mortality in the third trimester (50%) Pulmonary edema |
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To diagnose cholera, what are the transport medias?
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Transport media:
cary Blair Alkaline Peptone Water Strips of Filter Paper |
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How do you rapidly diagnose cholera?
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Rapid Diagnosis:
Dark Field Microscopy Florescent Antibody Co-Agglutination; Antigen detection strips |
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What do you use to culture cholera?
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TCBS Agar (Thiosulfate Citrate Bile salt Sucrose)
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What serologic tests are available for cholera?
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Serologic Tests:
Antitoxin antibodies Vibriocidal antibodies |
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What antibiotics are sensitive to treat cholera in haiti
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Haiti strain sensitive to azithromycin, doxycycline, tetracycline and intermediate to ciprofloxacin
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What antibiotics are resistant to treat cholera in haiti
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Resistant to sulfisoxazole, furazolidone, nalidixic acid.
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cholera epi: describe endemic
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Endemic:
Young children at greatest risk Multiple reservoirs and routes of transmission High numbers of seropositive persons Common to have asymptomatic infections |
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cholera epi: describe epidemic
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Epidemic:
All age groups affected Few reservoirs and modes of transmission Few are asymtomatic Most individuals seronegative |
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What are the short term goals of controlling cholera?
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Short-term:
Emergency Interventions Case detection and treatment Health Education Chlorination of water |
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What are the long term goals of controlling cholera?
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Long-term:
Sanitary reform Ongoing health education |
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What are the KEY ELEMENTS FOR HEALTH EDUCATION OF THE PUBLIC?
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* With appropriate treatment, cholera is not fatal
* Most cases can be treated with simple measures *Disposal of infected human feces in ways that do not present a health hazards * Good personal hygiene avoids transmission of cholera *Hygienic food preparation and proper cleaning of utensils * Clean water to be used for both drinking and bathing * Vaccination is not effective for cholera prevention (although this is being re-assessed) |
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is mass chemoprophylaxis in cholera epidemics good? why?
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No
1. MASS CHEMOPROPHYLAXIS has never been successful in controlling propagation of cholera 2. Disappointing results in the past because: * By the time antibiotic distribution and administration is organized, the outbreak has already propagated * Effect is limited to a few days * An entire population would need to be treated and then isolated to prevent reinfection *It is very difficult to convince asymptomatic individuals to take prophylaxis |
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Name the cholera vaccinations
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Inactivated Whole cell/B subunit oral vaccine (WC/rBS)
Sanchol (India) mORCVAX (Vietnam) Live attenuated CVD 103 HgR (genetically modified) no longer manufactured; |
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Describe WC/rBS, how it works and the dosing schedule
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Whole cell V. cholerae O1 (formalin and heat killed; El Tor and Classical; Ogawa and Inaba) combined with recombinant B subunit [Dukoral™; Sweden]
Vaccine must be given with bicarbonate to prevent destruction of B subunit by gastric acid; provided in single dose 3 ml vials along with bicarbonate in sachets, both mixed in standard volume water (75-150 ml) 2 doses given > 7 days apart (but < 6 weeks apart) Licensed in Canada since 2003 for travelers Good safety profile |
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What are the pros and cons of Sanchol (India) and mORCVAX (Vietnam) - compared to WC/rBS?
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Like WC/rBS, but does not contain B subunit--does not require bicarbonate and much cheaper to produce
Not as protective as WC/rBS |
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Describe the Si/Sx of a typical cholera disease
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Vomiting, frequent and voluminous liquid stools
Degree of dehydration depends on stool losses, which are especially intense during the first 48 hours (500 ml- 1 liter/hour) Absence of nausea, absence of blood or bile in the emesis Clear, liquid, "rice water" stools Duration of symptoms for 4-6 days for patients receiving rehydration but no antibiotics |
