Zimbabwe offers the most recent example of the tragedy that befalls a country and its people when cholera strikes. The 2008–2009 outbreak rapidly spread across every province and brought rates of mortality similar to those witnessed as a consequence of cholera infections a hundred years ago. In this Review we highlight the advances that will help to unravel how interactions between the host, the bacterial pathogen and the lytic bacteriophage might propel and quench cholera outbreaks in endemic settings and in emergent epidemic regions such as Zimbabwe.

OBJECTIVES. This study evaluated the production of dry fermented salami associated with an outbreak of Escherichia coli O157.H7 infection in Washington State and California. METHODS. Facility inspections, review of plant monitoring data, food handler interviews, and microbiological testing of salami products were conducted. RESULTS. Production methods complied with federal requirements and industry-developed good manufacturing practices. No evidence suggested that postprocessing contamination occurred. Calculations suggested that the infectious dose was smaller than 50 E. coli O157:H7 bacteria. CONCLUSIONS. Dry fermented salami can serve as a vehicle of transmission for O157:H7 strains. Our investigation and prior laboratory studies suggest that E. coli O157:H7 can survive currently accepted processing methods.

Vibrio vulnificus is a potentially lethal human pathogen capable of producing septicemia in susceptible persons. Disease is almost always associated with consumption of seafood, particularly raw oysters, or with exposure of wounds to seawater. An oligonucleotide DNA probe (V. vulnificus alkaline phosphatase-labeled DNA probe [VVAP]), previously shown to be highly specific for V. vulnificus, was used to enumerate this species in environmental samples collected from the Chesapeake Bay between April 1991 and December 1992. Total aerobic, heterotrophic, culturable bacteria were enumerated by plate counts on nonselective medium. The number of V. vulnificus organisms was determined by colony lifts of spread plates for subsequent hybridization with VVAP. V. vulnificus was not detected in any samples collected during February and March (water temperature of < 8 degrees C) but was found in 80% of the water samples collected during May, July, September, and December (water temperature of > 8 degrees C), with concentrations ranging from 3.0 x 10(1) to 2.1 x 10(2)/ml (ca. 8% of the total culturable heterotrophic bacteria). In a multiple regression analysis, increased V. vulnificus concentrations were correlated with lower salinities and with isolation from samples collected closer to the bottom. Isolation from oysters was demonstrable when water temperatures were 7.6 degrees C, with concentrations ranging from 1.0 x 10(3) to 4.7 x 10(4)/g (ca. 12% of total culturable bacteria). In samples collected in May and July, V. vulnificus was identified in seven of seven plankton samples and four of nine sediment samples. Our data demonstrate that V. vulnificus is a widespread and important component of the bacterial population of the Chesapeake Bay, with counts that are comparable to those reported from the Gulf of Mexico.

In this study, 27 volunteers received one of three non-O group 1 Vibrio cholerae strains in doses as high as 109 CFU. Only one strain (strain C) caused diarrhea: this strain was able to colonize the gastrointestinal tract, and produced a heat-stable enterotoxin (NAG-ST). Diarrhea was not seen with a strain (strain A) that colonized the intestine but did not produce NAG-ST, nor with a strain (strain B) that produced NAG-ST but did not colonize. Persons receiving strain C had diarrhea and abdominal cramps. Diarrheal stool volumes ranged from 154 to 5,397 ml; stool samples from the patient having 5,397 ml of diarrhea were tested and found to contain NAG-ST. The median incubation period for illness was 10 h. There was a suggestion that occurrence of diarrhea was dependent on inoculum size. Immune responses to homologous outer membrane proteins, lipopolysacchide, and whole-cell lysates were demonstrable with all three strains.Our data demonstrate that V. cholerae of 0 groups other than I are able to cause severe diarrheal disease. However, not all strains are pathogenic for humans: virulence of strain C may be dependent on its ability both to colonize the intestine and to produce a toxin such as NAG-ST. (J. Clin. Invest. 1990.

Although Vibrio cholerae O139 synonym Bengal strains, from the current epidemics in India and Bangladesh, are closely related to seventh-pandemic strains, as shown by multilocus enzyme electrophoresis, Bengal strains are encapsulated and portions of the O1 antigen biosynthetic complex genes found in O1 strains are altered or lacking. Encapsulated Bengal strains showed resistance to killing by normal human serum. The presence of the capsule suggests the potential for bloodstream invasion in susceptible hosts and has profound implications for vaccine development.

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Abstract-We evaluate the error-correcting performance of a low-density parity-check (LDPC) code in an AWGN channel using a novel dual adaptive importance sampling (DAIS) technique based on multicanonical Monte Carlo (MMC) simulations, that allows us to calculate bit error rates as low as 10 −19 for a (96, 50) LDPC code without a priori knowledge of how to bias. Our results agree very well with standard MC simulations, as well as the union bound for the code.

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