Cholera+strain+and+vaccination

Mayo clinic says only provides 25-50% immunity. If staying in an area of the world where cholera is prevalent, you probably need a booster every 6 months. []

Data from this study provides evidence that the cholera strain prevalent in Haiti began when a cholera strain was introduced from a distant geographic source. The strain in Haiti is a variant of the south Asian strain, El Tor. It is nearly identical to the El Tor O1 strains. It is unclear how it was introduced to Haiti after the earthquake. The bacterial isolates of V. cholerea identified in Haiti are refered to as H1 and H2. []

Long term protection is not provided by the vaccine. 67508 persons where in this study, half of which were given a placebo and half were given the vaccine. 43 vaccinated patients got cholera (O1 El Tor), while 50 placebo patients got cholera. This implies an efficiency of 14% for the vaccine.

Biotypes and serotypes are ways of classifying bacteria into subspecies. Biotypes are more broad of a group than serotypes. El tor is the biotype. O1 or H1 or H2 would be the serotypes.

( Richie et al., 2000 Richie, E., N. H. Punjabi, et al. (2000). "Efficacy trial of single-dose live oral cholera vaccine CVD 103-HgR in North Jakarta, Indonesia, a cholera-endemic area." Vaccine 18(22): 2399-2410.)

Important Highlights from the following article:

At present, no such vaccination is planned. Experts disagree over whether vaccinating against cholera during an outbreak is effective. There is also a worldwide shortage of vaccine.

One-quarter of Haitians live next to rivers, where the //Vibrio cholerae// bacterium seems to thrive. The long absence of epidemics means there is probably little or no natural immunity, and the strain causing the current epidemic is more virulent than those seen elsewhere in the past. Cholera may well become endemic, says Chao. And vaccines confer immunity for only about 2.5 years, he adds, making revaccination necessary. But even if it is agreed that vaccination would be effective, there are not enough doses in the world to treat all 10 million Haitians. Last December, Haiti's Ministry of Health decided not to vaccinate, a decision that it is standing by. "At the beginning of the epidemic, vaccination was considered, but given the limited global vaccine supply and other issues [such as fairness], cholera vaccinating was not considered practical," says Carolina Danovaro, a regional immunization adviser at PAHO. There are probably between 400,000 and 600,000 doses of oral cholera vaccine worldwide, says Longini. A course of vaccination requires two doses.

http://www.nature.com/news/2011/110411/full/news.2011.226.html

//Death rates on cholera//

//untreated cholera: about 50%// //properly treated cholera: less than 1%//

//(2004). "Cholera." Lancet 363(9404): 223-233.//

//Death rates in Haiti://

"Through our network of community health workers, we have learned of hundreds of patients who died at home or en route to the hospital. __In the first 48 hours, the case fatality rate at our facilities was as high as 10%. Though it dropped to less than 2% in the ensuing days as the health system was reinforced l__ocally and patients began to present earlier in the course of disease, mortality will most likely climb as the disease spreads and Haiti’s fragile health system falters."

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Antibodies last for 2-7 months http://www.textbookofbacteriology.net/cholera_4.html