The 1854 English cholera outbreak led to reform of Victorian public health legislation, including the Nuisances Removal and Diseases Prevention Act. The reforms threatened the closure of many factories whose fumes were considered hazardous to the public's health. The second witness to appear before the Parliamentary committee considering the reforms was Dr. John Snow. Snow testified on behalf of the manufacturers threatened by the reforms. He stated that the fumes from such establishments were not hazardous. He contended that the workers in these factories did not become ill as a result of their exposures, and therefore these fumes could not be a hazard to the general public's health. Snow also presented data from the 1854 cholera outbreak as the basis for his belief that epidemic diseases were transmitted by water, not air. Although the data concerned cholera, Snow extended the inference to all epidemic diseases. When the committee's report was published, The Lancet chastised Snow in a stinging editorial. Parliament subsequently revised the bill in favor of the manufacturers and passed it into law. The implications of this particular episode in the history of epidemiology are discussed. (+info)
Geographical patterns of cholera in Mexico, 1991-1996.
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BACKGROUND: The seventh cholera pandemic has been ongoing in Mexico since 1991 and threatens to become endemic. This paper aims to determine the geographical pattern of cholera in Mexico to define areas at high risk of endemic cholera. METHODS: Ecologic research was conducted based upon the cartography of disease incidence. The 32 Mexican states were grouped into five strata according to the value of the 1991-1996 cumulative incidence rate of cholera. Rate ratios were computed for strata of states classified by geographical situation, urbanization, and poverty level. RESULTS: Cholera incidence was 2.47 times higher in coastal states than in the interior (95% CI : 2.42-2.52). The disease was negatively associated with urbanization. Incidence in the least urbanized stratum was four times as high as in the most urban stratum (95% CI : 3.9-4.12). The poorest stratum showed the most remarkable incidence, i.e. 5.9 times higher than the rate in the least poor stratum (95% CI : 5.73-6.04). CONCLUSIONS: This ecologic research suggests that high poverty level, low urbanization, and southern location are the most important predictors of endemic cholera in Mexican states. It is hypothesized that the natural environment of the coastal plains in southern states may also play a significant role in cholera incidence. Poor communities residing in the southern, predominantly rural, coastal states should be prioritized when it comes to investing in safe water supply facilities, adequate excreta disposal systems and cholera surveillance. (+info)
Protection from cholera by adding lime juice to food - results from community and laboratory studies in Guinea-Bissau, West Africa.
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Epidemiological studies have shown that food plays an important role in the transmission of Vibrio cholerae, and different foods have been incriminated in many epidemic outbreaks of cholera. Storing contaminated meals at ambient temperatures allows growth of V. cholerae. Some ingredients such as lime juice may inhibit the survival of V. cholerae in foods. During an epidemic caused by V. cholerae O1 in Guinea-Bissau in 1996, a case control study was conducted in the capital Bissau, the main affected region with an attack rate of 7.4%. Cases were hospitalized patients and controls were matched for area, gender and age. Lime juice in the sauce eaten with rice gave a strong protective effect (odds ratio [OR] = 0.31, 95% confidence interval [CI] = 0.17-0.56), and tomato sauce was also protective (OR = 0.36, 95% CI = 0.24-0.54). On the other hand, use of a bucket for storage of water in the house was associated with increased risk (OR = 4.4, CI = 2.21-8.74). Laboratory experiments to elucidate the inhibitory effect of different concentrations of lime juice on survival of V. cholerae in meals showed that V. cholerae thrives in rice with peanut sauce, but lime juice inhibited its growth. Since lime juice is a common ingredient of sauces, its use should be further encouraged to prevent foodborne transmission in the household during cholera outbreaks. (+info)
Virulence genes in environmental strains of Vibrio cholerae.
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The virulence of a pathogen is dependent on a discrete set of genetic determinants and their well-regulated expression. The ctxAB and tcpA genes are known to play a cardinal role in maintaining virulence in Vibrio cholerae, and these genes are believed to be exclusively associated with clinical strains of O1 and O139 serogroups. In this study, we examined the presence of five virulence genes, including ctxAB and tcpA, as well as toxR and toxT, which are involved in the regulation of virulence, in environmental strains of V. cholerae cultured from three different freshwater lakes and ponds in the eastern part of Calcutta, India. PCR analysis revealed the presence of these virulence genes or their homologues among diverse serotypes and ribotypes of environmental V. cholerae strains. Sequencing of a part of the tcpA gene carried by an environmental strain showed 97.7% homology to the tcpA gene of the classical biotype of V. cholerae O1. Strains carrying the tcpA gene expressed the toxin-coregulated pilus (TCP), demonstrated by both autoagglutination analysis and electron microscopy of the TCP pili. Strains carrying ctxAB genes also produced cholera toxin, determined by monosialoganglioside enzyme-linked immunosorbent assay and by passage in the ileal loops of rabbits. Thus, this study demonstrates the presence and expression of critical virulence genes or their homologues in diverse environmental strains of V. cholerae, which appear to constitute an environmental reservoir of virulence genes, thereby providing new insights into the ecology of V. cholerae. (+info)
A cytotoxin-producing strain of Vibrio cholerae non-O1, non-O139 as a cause of cholera and bacteremia after consumption of raw clams.
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We report a case of a cholera-like gastroenteritis subsequent with bacteremia in a healthy man following consumption of raw clams. Although we failed to recover the organism from the patient's stool culture, his blood culture was positive for a non-cholera toxin-producing yet cytotoxin-producing non-O1 and non-O139 Vibrio cholerae. (+info)
Cholera dynamics and El Nino-Southern Oscillation.
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Analysis of a monthly 18-year cholera time series from Bangladesh shows that the temporal variability of cholera exhibits an interannual component at the dominant frequency of El Nino-Southern Oscillation (ENSO). Results from nonlinear time series analysis support a role for both ENSO and previous disease levels in the dynamics of cholera. Cholera patterns are linked to the previously described changes in the atmospheric circulation of south Asia and, consistent with these changes, to regional temperature anomalies. (+info)
The O139 serogroup of Vibrio cholerae comprises diverse clones of epidemic and nonepidemic strains derived from multiple V. cholerae O1 or non-O1 progenitors.
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Sixty-four representative strains of Vibrio cholerae O139 were analyzed, to re-examine the origin of this serogroup. Ribotyping differentiated the strains into 3 HindIII and 7 BglI ribotypes. One HindIII and 5 BglI ribotypes were shared by all toxigenic O139 strains. Of 6 nontoxigenic O139 strains, 3 shared ribotypes with the toxigenic strains, carried genes encoding toxin coregulated pilus, and were susceptible to the cholera toxin-converting bacteriophage CTXPhi. The remaining 3 strains belonged to 2 different ribotypes distinct from toxigenic O139 strains and were resistant to CTXPhi and JA-1, an O139-specific lytic bacteriophage. Polymerase chain reaction amplicons corresponding to the gmhD gene carried by these 3 strains also differed from those of the toxigenic O139 strains but were identical to those of 15 environmental non-O1-non-O139 strains. Thus, the O139 antigen is present in different lineages, and this serogroup appears to comprise epidemic and nonepidemic strains derived separately from different progenitors. (+info)
Expanding multiple antibiotic resistance among clinical strains of Vibrio cholerae isolated from 1992-7 in Calcutta, India.
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Antimicrobial susceptibilities of Vibrio cholerae strains isolated from cholera patients admitted to the Infectious Diseases Hospital, Calcutta, India for 6 years were analysed to determine the changing trends; 840 V. cholerae strains isolated in 1992-1997 were included in this study. Among V. cholerae serogoup O1 and O139, ampicillin resistance increased from 1992 (35 and 70%, respectively) to 1997 (both serogroups 100%). Resistance to furazolidone and streptomycin was constantly high among V. cholerae O1 strains with gradual increase in resistance to other drugs such as ciprofloxacin, co-trimoxazole, neomycin and nalidixic acid. V. cholerae O139 strains exhibited susceptibilities to furazolidone and streptomycin comparable with those of O1 strains. However, after initial increase in resistance to chloramphenicol and co-trimoxazole, all the V. cholerae O139 strains became susceptible to these two drugs from 1995 onwards. Both V. cholerae O1 and O139 remained largely susceptible to gentamicin and tetracycline. V. cholerae non-O1, non-O139 strains, in contrast, exhibited high levels of resistance to virtually every class of antimicrobial agents tested in this study especially from 1995. Kruskal-Wallis one-way analysis showed that V. cholerae O1 Ogawa serogroup exhibited significant yearly increase in resistance to nine antibiotics followed by non-O1 non-O139 and O139 strains to six antibiotics and two antibiotics respectively. Interesting observation encountered in this study was the dissipation of some of the resistant patterns commonly found among V. cholerae non-O1 non-O139 or O1 serogroups to the O139 serogroup and vice versa during the succeeding years. (+info)