El Tor cholera with severe disease: A new threat to Asia and beyond

Public Health Sciences Division (PHSD), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh.
Epidemiology and Infection (Impact Factor: 2.54). 09/2009; 138(3):347-52. DOI: 10.1017/S0950268809990550
Source: PubMed


During epidemics of cholera in two rural sites (Bakerganj and Mathbaria), a much higher proportion of patients came for treatment with severe dehydration than was seen in previous years. V. cholerae O1 isolated from these patients was found to be El Tor in its phenotype, but its cholera toxin (CT) was determined to be that of classical biotype. Whether the observed higher proportion of severe dehydration produced by the El Tor biotype was due to a shift from El Tor to classical CT or due to other factors is not clear. However, if cholera due to strains with increased severity spread to other areas where treatment facilities are limited, there are likely to be many more cholera deaths.

Download full-text


Available from: Rita R Colwell,
  • Source
    • "Amongst 209 known V. cholerae serogroups, O1 and O139 are the predominant causes of cholera outbreaks. In recent years, the O1 serogroup El Tor biotype is the major biotype implicated in cholera, replacing the previously circulating classical biotype [1]. Of the two serotypes of the El Tor biotype, Ogawa and Inaba, the Ogawa serotype was predominant in past years. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, we demonstrated oral immunizations with single serotype outer membrane vesicles of Vibrio cholerae induced serogroup specific protective immunity in the RITARD model. In our present study, we advanced our research by formulating multi-serotype outer membrane vesicles, mixing the OMVs of five virulent V. cholerae strains. Four doses of oral immunization with cholera pentavalent outer membrane vesicles (CPMVs) induced V. cholerae specific B and T cell responses. CPMVs-immunized mice generated long lasting serum IgG, IgA, IgM as well as mucosal sIgA and also elicited a higher percentage of CD4+ T cell distribution in spleen. Our study revealed that in vitro CPMVs-activated dendritic cells were secreting T cell polarizing cytokines, IL-12p40, IL-4, IL-6 and IL-1β. Moreover, purified splenic CD4+ T cells of immunized mice also secreted IL-4, IL-13 and IL-17 cytokines, indicating the initiation of Th2 and Th17 cell mediated immune responses. CPMVs immunized adult female mice and their offspring were significantly protected from heterologous challenge with wild type V. cholerae. CPMVs could be exploited for the development of a novel non-living vaccine against circulating cholera in near future.
    Microbes and Infection 11/2014; 17(3). DOI:10.1016/j.micinf.2014.10.011 · 2.86 Impact Factor
  • Source
    • "According to a recent report, altered ET strains were predominant among CL and ET biotype progenitors associated with endemic cholera in Mexico between 1991 and 1997 (Alam et al., 2010). Such altered ET strains were found to cause a more severe disease in Asia (Siddique et al., 2010), and are being reported globally (Chin et al., 2011; Na-Ubol et al., 2011; Okada et al., 2010; Goel et al., 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cholera, caused by Vibrio cholerae, results in significant morbidity and mortality worldwide, including Thailand. Representative V. cholerae strains associated with endemic cholera (n=32), including strains (n=3) from surface water sources, in Khon Kaen, Thailand (2003 - 2011) were subjected to microbiological, molecular, and phylogenetic analyses. According to phenotypic and related genetic data, all tested V. cholerae strains belonged to serogroup O1, biotype El Tor (ET), Inaba (IN) or Ogawa (OG). All of the strains were sensitive to gentamycin and ciprofloxacin, while multidrug resistant (MDR) strains showing resistance to erythromycin (E), tetracycline (TE), trimethoprim/sulfamethoxazole (SXT), and ampicillin (AMP) were predominant in 2007. V. cholerae strains isolated before and after 2007 were non-MDR. All except six diarrheal strains possessed ctxA and ctxB genes and were toxigenic altered ET, confirmed by MAMA-PCR, DNA sequencing and analyses. Year-wise data revealed V. cholerae INET strains isolated between 2003 and 2004, including one strain isolated in 2007, lacked RS1 sequence (rstC) and toxin-linked cryptic plasmid (TLC)-specific genetic marker, but possessed CTXCL prophage genes ctxBCL and rstRCL. A sharp genetic transition was noted, namely the majority of V. cholerae strains in 2007 and all in 2010 and 2011 were not repressor genotype rstRCL but instead were rstRET and all ctx+ strains possessed RS1 and TLC-specific genetic markers. DNA sequencing and analyses revealed that strains isolated since 2007 had a mutation in tcpA gene at amino acid position 64 (N→S). Four clonal types, mostly of environmental origin, including subtypes, reflected genetic diversity, while distinct signatures were observed for clonally related, altered ET of Thailand, Vietnam, and Bangladesh, confirmed by distinct sub-clustering patterns observed in the PFGE (NotI)-based dendrogram, suggesting endemic cholera is caused by V. cholerae indigenous to Khon Kaen.
    Journal of Medical Microbiology 01/2013; 62(Pt_4). DOI:10.1099/jmm.0.053801-0 · 2.25 Impact Factor
  • Source
    • "Subsequent retrospective studies showed that all of the O1 ET strains isolated in Bangladesh since 2001 were hybrids of both CL and ET biotypes, while those isolated before 2001 contained all the ET attributes of the seventh pandemic V. cholerae O1 (Nair et al., 2006). V. cholerae hybrid ET continues to be routinely isolated from clinical cholera cases in Asia and Africa (Safa et al., 2008), and has been reported to be a new pandemic pathogen capable of causing more severe disease (Siddique et al., 2010), which is spreading globally (Chin et al., 2011). A recent study in India reported that a new CT variant of V. cholerae O1 ET with an amino acid substitution at position 20 caused a large cholera outbreak in Orissa, Eastern India (Kumar et al., 2009). "

Show more