The aquatic environment as a reservoir of Vibrio cholerae O1 in hydrographic basins of the state of Pernambuco, Brazil

After the worldwide cholera epidemic in 1993, permanent environmental monitoring of hydrographic basins was established in Pernambuco, Brazil, where cholera is endemic. After a quiescent period, 4 rfbN (serogroup O1) positive water samples that were culture negative were detected by multiplex single-tube nested PCR (MSTNPCR); 2 of these were also ctxA (cholera toxin) positive. From May to June 2012, 30 V. cholerae O1 isolates were obtained by culturing samples. These isolates were analyzed for the presence of virulence genes by PCR, intergenic spacer region 16S-23S PCR (ISR-PCR), and pulsed field gel electrophoresis (PFGE). The isolates were positive for the rfbN gene and negative for the assessed pathogenic genes and were classified into 2 groups by ISR and the same profile by PFGE. Close genetic similarity was observed between them (2012) and environmental strains from 2004 to 2005, indicating the permanence of endemic V. cholerae O1 in the region.

Clinical isolates of Vibrio cholerae O1 El Tor Ogawa of 2009 from Kolkata, India: preponderance of SXT element and presence of Haitian ctxB variant

Background

Increase in the number of multidrug resistant pathogens and the accompanied rise in case fatality rates has hampered the treatment of many infectious diseases including cholera. Unraveling the mechanisms responsible for multidrug resistance in the clinical isolates of Vibrio cholerae would help in understanding evolution of these pathogenic bacteria and their epidemic potential. This study was carried out to identify genetic factors responsible for multiple drug resistance in clinical isolates of Vibrio cholerae O1, serotype Ogawa, biotype El Tor isolated from the patients admitted to the Infectious Diseases Hospital, Kolkata, India, in 2009.

Methodology/Principal Findings

One hundred and nineteen clinical isolates of V. cholerae were analysed for their antibiotic resistance phenotypes. Antibiogram analysis revealed that majority of the isolates showed resistance to co-trimoxazole, nalidixic acid, polymixin B and streptomycin. In PCR, SXT integrase was detected in 117 isolates and its sequence showed 99% identity notably to ICEVchInd5 from Sevagram, India, ICEVchBan5 from Bangladesh and VC1786ICE sequence from Haiti outbreak among others. Antibiotic resistance traits corresponding to SXT element were transferred from the parent Vibrio isolate to the recipient E. coli XL-1 Blue cells during conjugation. Double-mismatch-amplification mutation assay (DMAMA) revealed the presence of Haitian type ctxB allele of genotype 7 in 55 isolates and the classical ctxB allele of genotype 1 in 59 isolates. Analysis of topoisomerase sequences revealed the presence of mutation Ser83 → Ile in gyrA and Ser85→ Leu in parC. This clearly showed the circulation of SXT-containing V. cholerae as causative agent for cholera in Kolkata.

Conclusions

There was predominance of SXT element in these clinical isolates from Kolkata region which also accounted for their antibiotic resistance phenotype typical of this element. DMAMA PCR showed them to be a mixture of isolates with different ctxB alleles like classical, El Tor and Haitian variants.

Cholera surveillance during the Haiti epidemic--the first 2 years

BACKGROUND

In October 2010, nearly 10 months after a devastating earthquake, Haiti was stricken by epidemic cholera. Within days after detection, the Ministry of Public Health and Population established a National Cholera Surveillance System (NCSS).

METHODS

The NCSS used a modified World Health Organization case definition for cholera that included acute watery diarrhea, with or without vomiting, in persons of all ages residing in an area in which at least one case of Vibrio cholerae O1 infection had been confirmed by culture.

RESULTS

Within 29 days after the first report, cases of V. cholerae O1 (serotype Ogawa, biotype El Tor) were confirmed in all 10 administrative departments (similar to states or provinces) in Haiti. Through October 20, 2012, the public health ministry reported 604,634 cases of infection, 329,697 hospitalizations, and 7436 deaths from cholera and isolated V. cholerae O1 from 1675 of 2703 stool specimens tested (62.0%). The cumulative attack rate was 5.1% at the end of the first year and 6.1% at the end of the second year. The cumulative case fatality rate consistently trended downward, reaching 1.2% at the close of year 2, with departmental cumulative rates ranging from 0.6% to 4.6% (median, 1.4%). Within 3 months after the start of the epidemic, the rolling 14-day case fatality rate was 1.0% and remained at or below this level with few, brief exceptions. Overall, the cholera epidemic in Haiti accounted for 57% of all cholera cases and 53% of all cholera deaths reported to the World Health Organization in 2010 and 58% of all cholera cases and 37% of all cholera deaths in 2011.

CONCLUSIONS

A review of NCSS data shows that during the first 2 years of the cholera epidemic in Haiti, the cumulative attack rate was 6.1%, with cases reported in all 10 departments. Within 3 months after the first case was reported, there was a downward trend in mortality, with a 14-day case fatality rate of 1.0% or less in most areas.

Case of imported Vibrio cholerae O1 from India to South Africa

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[The optimization of conditions of diagnostic fluorescent monoclonal immunoglobulins production to identify comma bacillus of serogroups O1 and O139]

The article considers, the issue of producing the species-specific fluorescent monoclonal immunoglobulins to detect comma bacillus of serogrups O1 and O139 in the reaction of direct immunfluorescence. It is established that not only ascitic but culture fluid too can be the source of monoclonal antibodies for producing fluorescent conjugates. The optimal conditions are selected to produce the fluorescent monoclonal immunoglobulins-monoclonal antibodies. The corresponding producing techology can be reproduced at any time in view of availability of hybrid-producers of monoclonal antibodies O1 and monoclonal antibodies O139 in the institute cryodepositoty. The results of testing the fluorescent preparations on homologous and heterologous strains demonstrated their strict specificiy and high sensibility regarding comma bacillus of serogroups O1 and O139. The new preparations favor significant increase of effectiveness of diagnostics of V. cholerae O1 and O139.

Molecular analysis and antimicrobial resistance of Vibrio cholerae O1 in northeastern Thailand

A total of 84 clinical Vibrio cholerae O1 isolates were collected from Khon Kaen (KK), Udon Thani (UT), Loei (LI), and Nong Khai (NK), northeastern Thailand during cholera outbreaks in 2007 and 2008. The majority of V. cholerae O1 strains carried nearly all the virulence-associated genes (ctxA, zot, and ace) except for four isolates and one isolate from UT and NK, respectively, which carried only tcpA, ompU, hlyA and toxR. None of the V. cholerae O1 strains carried sto. Pulsed field gel-electrophoresis (PFGE) profiling of 16 randomly chosen isolates showed the same PFGE pattern, except for one NK isolate, which was sensitive to all seven antibiotics used in the antimicrobial susceptibility tests. The tests revealed that multi-drug resistance to tetracycline and co-trimoxazole were present in KK strains (92%), followed by LI (75%) and UT (52%) strains. All strains were sensitive to norfloxacin but intermediate resistance to ciprofloxacin was found in a single strain from KK and LI. Differences in antimicrobial resistance among V. cholerae strains with the same PFGE pattern reflect differences in the antimicrobial agents used in each area of northeastern Thailand.

Changing trend of persistent diarrhoea in young children over two decades: observations from a large diarrhoeal disease hospital in Bangladesh

AIM

  We studied the changing trend and factors associated with persistent diarrhoea (PD) in under-five children presenting to a large diarrhoeal disease hospital in urban Dhaka, Bangladesh, over the last two decades.

METHODS

  We used an unmatched case-control design, with a case (persistent diarrhoea; n=944) to control (acute diarrhoea; n=2832) ratio of 1:3 attending the Dhaka Hospital of icddr,b between 1991 and 2010.

RESULTS

  The proportion of children with PD decreased significantly from 8% in 1991 to 1% in 2010. The proportion of breastfeeding practices, measles vaccination coverage and vitamin A supplementation among 12-59 months old improved from 79% to 85%, 69% to 85% and 26% to 74%, respectively, which were significant. Although the isolation of rotavirus from stool in children with PD and acute diarrhoea increased, the isolation of Shigella spp., and Vibrio cholerae O1 decreased significantly. In a logistic regression analysis, wasting (OR=1.62), use of antibiotic before attending hospital (OR=5.94), absent clinical dehydration (OR=1.53) and bloody/mucoid stool (OR=3.33) were significantly associated with persistent diarrhoea.

CONCLUSION

  There, thus, is a need to integrate an appropriate and sustainable deterrent strategy to take the benefit of the significant reduction in prevalence as well as risks of PD in such population.

Genetic characteristics of drug-resistant Vibrio cholerae O1 causing endemic cholera in Dhaka, 2006-2011

Vibrio cholerae O1 biotype El Tor (ET), causing the seventh cholera pandemic, was recently replaced in Bangladesh by an altered ET possessing ctxB of the Classical (CL) biotype, which caused the first six cholera pandemics. In the present study, V. cholerae O1 strains associated with endemic cholera in Dhaka between 2006 and 2011 were analysed for major phenotypic and genetic characteristics. Of 54 representative V. cholerae isolates tested, all were phenotypically ET and showed uniform resistance to trimethoprim/sulfamethoxazole (SXT) and furazolidone (FR). Resistance to tetracycline (TE) and erythromycin (E) showed temporal fluctuation, varying from year to year, while all isolates were susceptible to gentamicin (CN) and ciprofloxacin (CIP). Year-wise data revealed erythromycin resistance to be 33.3 % in 2006 and 11 % in 2011, while tetracycline resistance accounted for 33, 78, 0, 100 and 27 % in 2006, 2007, 2008, 2009 and 2010, respectively; interestingly, all isolates tested were sensitive to TE in 2011, as observed in 2008. All V. cholerae isolates tested possessed genetic elements such as SXT, ctxAB, tcpA(ET), rstR(ET) and rtxC; none had IntlI (Integron I). Double mismatch amplification mutation assay (DMAMA)-PCR followed by DNA sequencing and analysis of the ctxB gene revealed a point mutation at position 58 (C→A), which has resulted in an amino acid substitution from histidine (H) to asparagine (N) at position 20 (genotype 7) since 2008. Although the multi-resistant strains having tetracycline resistance showed minor genetic divergence, V. cholerae strains were clonal, as determined by a PFGE (NotI)-based dendrogram. This study shows 2008-2010 to be the time of transition from ctxB genotype 1 to genotype 7 in V. cholerae ET causing endemic cholera in Dhaka, Bangladesh.

Notes from the field: Identification of Vibrio cholerae serogroup O1, serotype Inaba, biotype El Tor strain - Haiti, March 2012

On October 20, 2010, an outbreak of cholera was confirmed in Haiti for the first time in more than a century. As of April 10, 2012, a total of 534,647 cases, 287,656 hospitalizations, and 7,091 deaths have been reported in Haiti as a result of the outbreak. The Vibrio cholerae strain that caused the Haiti epidemic has been characterized as toxigenic V. cholerae, serogroup O1, serotype Ogawa, biotype El Tor.

wbeT sequence typing and IS1004 profiling of Vibrio cholerae isolates

AIMS

To investigate the molecular basis for serotype variation in Vibrio cholerae O1 and the genetic relatedness amongst different serotypes isolated from 2004 to 2008 in Iran.

METHODS AND RESULTS

Despite the presence of all three serotypes of V.cholerae O1 (Ogawa, Inaba and Hikojima) in Iran in the last decade, the Inaba strains have been the dominated serotype. Sequence analysis of wbeT determined only a single substitution of G for A at position 295 in all Inaba strains resulting in a replacement of serine to proline. No difference was found in the copy numbers and profile of IS1004 between the classical and El Tor V. cholerae O1 strains, supporting the clonality amongst the isolates obtained over 5 years in Iran. In addition, Southern blots of HpaII-digested chromosomal DNAs of our Ogawa and Inaba isolates showed the presence of an incomplete copy of IS1004 for all isolates.

CONCLUSIONS

IS1004 profiling can be a reliable method for analysis of clonal dissemination of V. cholerae. The results indicated that specific point mutation at a particular position within the wbeT of V. cholerae O1 strains in Iran may occur which, in turn, may result in serotype switching.

SIGNIFICANCE AND IMPACT OF THE STUDY

Understanding the molecular basis for serotype conversion of V. cholerae and their genetic relatedness could give insights for the incoming cholera epidemic prediction and control.

Increasing antimicrobial resistance of Vibrio cholerae OI biotype E1 tor strains isolated in a tertiary-care centre in India

The antimicrobial susceptibility patterns are on constant change with the recent emergence of multidrug-resistant strains of most bacteria. Results of recent studies in India showed that most isolates of Vibrio cholerae O1 were resistant to the commonly-used antibiotics. The study was conducted to determine the antibiotic susceptibility patterns of V. cholerae O1 isolated during 2008-2010 at the hospital of the Jawaharlal Nehru Institute of Post Graduate Medical Education and Research, Puducherry, India. In total, 154 strains of V. cholerae O1 from 2,658 stool specimens were reported during January 2008-December 2010--34 in 2008, 2 in 2009, and 118 in 2010. The isolates of V. cholerae O1 were subjected to antimicrobial susceptibility testing using the Kirby-Bauer method. The antibiotic disks tested were tetracycline (30 microg), furazolidone (100 microg), ampicillin (10 microg), ceftriaxone (30 microg), and ciprofloxacin (5 microg). Escherichia coli ATCC 25922 was used as the control organism. The minimum inhibitory concentrations (MICs) of ceftriaxone, ciprofloxacin, and tetracycline were determined using the agar dilution method for all the strains. The E-test method was used for the strains which had either intermediate resistance or were resistant to the antibiotics by the agar dilution method. The results of the agar dilution corroborated the results of the E-test. The MIC of ceftriaxone in 151 strains was <2 microg/mL while it was 16 microg/mL in three strains; the latter three strains were resistant to ceftriaxone by the disc-diffusion test. The MIC of ciprofloxacin in 150 strains was <0.5 microg/mL while the MIC of tetracycline was <1 microg/mL. In the remaining four strains, the MIC of tetracycline was >32 microg/mL, and the MIC of ciprofloxacin was >8 microg/mL. These four strains were resistant to both tetracycline and ciprofloxacin by the disc-diffusion test and were exclusive of the three ceftriaxone-resistant strains. The majority of the isolates were obtained from children aged 0-5 year(s)-70.3% (83 of 118) and 41.2% (14 of 34) were reported in 2010 and 2008 respectively. Since treating severe cases of cholera with antibiotics is important, the continuing spread of resistance in V. cholerae to the most important agents of therapy is a matter of concern. Also, chemoprophylaxis with antimicrobial agents is likely to become even more difficult.

Genotypic and PFGE/MLVA analyses of Vibrio cholerae O1: geographical spread and temporal changes during the 2007-2010 cholera outbreaks in Thailand

BACKGROUND

Vibrio cholerae O1 El Tor dominated the seventh cholera pandemic which occurred in the 1960s. For two decades, variants of V. cholerae O1 El Tor that produce classical cholera toxin have emerged and spread globally, replacing the prototypic El Tor biotype. This study aims to characterize V. cholerae O1 isolates from outbreaks in Thailand with special reference to genotypic variations over time.

METHODS/FINDINGS

A total of 343 isolates of V. cholerae O1 from cholera outbreaks from 2007 to 2010 were investigated, and 99.4% were found to carry the classical cholera toxin B subunit (ctxB) and El Tor rstR genes. Pulsed-field gel electrophoresis (PFGE) differentiated the isolates into 10 distinct pulsotypes, clustered into two major groups, A and B, with an overall similarity of 88%. Ribotyping, multiple-locus variable-number tandem-repeat analysis (MLVA), and PCR to detect Vibrio seventh pandemic island II (VSP-II) related genes of randomly selected isolates from each pulsotype corresponded to the results obtained by PFGE. Epidemiological investigations revealed that MLVA type 2 was strongly associated with a cholera outbreak in northeastern Thailand in 2007, while MLVA type 7 dominated the outbreaks of the southern Gulf areas in 2009 and MLVA type 4 dominated the outbreaks of the central Gulf areas during 2009-2010. Only MLVA type 16 isolates were found in a Thai-Myanmar border area in 2010, whereas those of MLVA types 26, 39, and 41 predominated this border area in 2008. Type 39 then disappeared 1-2 years later as MLVA type 41 became prevalent. Type 41 was also found to infect an outbreak area.

CONCLUSIONS

MLVA provided a high-throughput genetic typing tool for understanding the in-depth epidemiology of cholera outbreaks. Our epidemiological surveys suggest that some clones of V. cholerae O1 with similar but distinctive genetic traits circulate in outbreak sites, while others disappear over time.

Structural variation of the superintegron in the toxigenic Vibrio cholerae O1 El Tor

OBJECTIVE

To understand the genetic structures and variations of the superintegron (SI) in Vibrio cholerae isolated in the seventh cholera pandemic.

METHODS

Polymerase chain reaction scanning and fragment sequencing were used. Sixty toxigenic V. cholerae O1 El Tor strains isolated between 1961 and 2008 were analyzed.

RESULTS

Some variations were found, including insertions, replacements, and deletions. Most of the deletions were probably the result of recombination between V. cholerae repeat sequences. The majority of the variations clustered together. The SIs of the strains isolated in the 1960s and 1970s showed more diversity, whereas SI cassette variations in strains isolated in the 1990s and after were lower, with ∼24 kb signature sequence deletion. This indicates the predominant SI in the host during the epidemic in the 1990s and after. The insertion cassettes suggested the mobilization from the SIs of other V. cholerae serogroups and Vibrio mimicus.

CONCLUSION

The study revealed that structural variations of SIs were obvious in the strains isolated in epidemics in different decades, whereas the divergence was based on syntenic structure of SIs in these El Tor strains. Also, the continuing cassette flows in the SIs of the host strains during the seventh cholera pandemics were displayed.

Efficacy of a low-cost, inactivated whole-cell oral cholera vaccine: results from 3 years of follow-up of a randomized, controlled trial

BACKGROUND

Killed oral cholera vaccines (OCVs) have been licensed for use in developing countries, but protection conferred by licensed OCVs beyond two years of follow-up has not been demonstrated in randomized, clinical trials.

METHODS/PRINCIPAL FINDINGS

We conducted a cluster-randomized, placebo-controlled trial of a two-dose regimen of a low-cost killed whole cell OCV in residents 1 year of age and older living in 3,933 clusters in Kolkata, India. The primary endpoint was culture-proven Vibrio cholerae O1 diarrhea episodes severe enough to require treatment in a health care facility. Of the 66,900 fully dosed individuals (31,932 vaccinees and 34,968 placebo recipients), 38 vaccinees and 128 placebo-recipients developed cholera during three years of follow-up (protective efficacy 66%; one-sided 95%CI lower bound = 53%, p<0.001). Vaccine protection during the third year of follow-up was 65% (one-sided 95%CI lower bound = 44%, p<0.001). Significant protection was evident in the second year of follow-up in children vaccinated at ages 1-4 years and in the third year in older age groups.

CONCLUSIONS/SIGNIFICANCE

The killed whole-cell OCV conferred significant protection that was evident in the second year of follow-up in young children and was sustained for at least three years in older age groups. Continued follow-up will be important to establish the vaccine's duration of protection.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00289224.

[Molecular characteristics and antibiotic resistances of Vibrio cholerae O1 isolates in Hangzhou in 2009]

OBJECTIVE

To study the molecular characteristics and antibiotic resistances of Vibrio cholerae (V. cholerae) O1 isolates in Hangzhou in 2009.

METHODS

The virulence genes ctxA and tcpA of the thirty V. cholerae O1 isolates from 7 counties and districts of Hangzhou were detected by PCR. Pulsed-field gel electrophoresis (PFGE) was performed for molecular typing and similarity analysis. Antibiotic resistances of these isolates were measured by the Kirby-Bauer method.

RESULTS

Virulence gene analysis showed that 80.00% (24/30) of the genotype in V. cholerae isolates was ctxA- and tcpA+, 13.33% (4/30) was ctxA- and tcpA-, and 6.67% (2/30) was ctxA+ and tcpA+. Twenty-seven isolates tested were typed into 11 PFGE patterns (P1-P11). Twenty-three isolates with genotype ctxA- and tcpA+ were clustered into 7 PFGE patterns (P1-P7, termed P1-like cluster) with the similarity to be equal or greater than 91.4%, and 56.52%(13/23) of them belong to P1. 7 isolates with very high similarity (97.6%), belonging to P1 (6 isolates), and P2 (1 isolate), respectively, were collected from one foodborne disease outbreak. The resistant rates of the 24 isolates with genotype ctxA- and tcpA+ to ampicillin, tobramycin and amikacin were 20.83% (5/24), 4.17% (1/24) and 4.17% (1/24), respectively.

CONCLUSION

The genotype of the epidemic strains of V. cholerae O1 isolates in Hangzhou in 2009 with high similarity was ctxA- and tcpA+; The level of drug resistances of this kind of V. cholerae O1 isolates were not high.

Resistotypes of Vibrio cholerae 01 Ogawa Biotype El Tor in Kathmandu, Nepal

Cholera continued to be a major diarrheal illness in Nepal and antibiotic resistance has appeared as a serious problem in cholera management. The study aimed at analyzing the distribution pattern of the resistotypes (R-types) of Vibrio cholerae in the Kathmandu valley, Nepal. During June 2008 to January 2009, 210 diarrheal specimens received at National Public Health Laboratory from suspected cholera patients were subjected to standard bacteriological investigation including biotyping and serotyping. Antimicrobial susceptibility pattern of V. cholerae isolates was determined by Kirby Bauer disc diffusion method following CLSI guidelines. A total of 57 (27%) V. cholerae isolated were recovered, all of which belonged to 01 Ogawa Biotype EL Tor. Based on antibiogram, V. cholerae isolates in our study revealed three distinct R-types: R-type I, R-type II and R-type III. All three R types showed resistance to furazolidone, nalidixic acid and cotrimoxazole while sensitive to ciprofloxacin and tetracycline. Additional resistance to ampicillin and erythromycin was observed respectively in R-type II and III. Different R-types showed unique month wise variations (P < 0.05). Differentiation of V. cholerae strains into R-types is an important tool. In addition to direct patient management, it may have implication in identifying the source and spread of infection, and understanding the distribution pattern in a particular geographical region.

The 2010 outbreak of cholera among workers of a jute mill in Kolkata, West Bengal, India

On 10 March 2010, an outbreak of diarrhoeal disease was reported among workers of a jute mill in Kolkata, West Bengal, India. The cluster was investigated to identify the agent(s) and the source of infection and make recommendations. A suspected case of cholera was defined as having >3 loose watery stools in a 24-hour period and searched for case-patients in the workers' colony. The outbreak was described by time, place, and person, and a case-control study was conducted to identify the source of infection. Rectal swabs were collected from the hospitalized case-patients, and the local water-supply system was assessed. In total, 197 case-patients were identified among 5,910 residents of the workers' colony (attack rate 3.33%). Fifteen of 24 stool samples were positive for Vibrio cholerae O1. The outbreak started on 7 March, peaked on 11 March, and ended on 16 March 2010. Compared to 120 controls, 60 cases did not differ in terms of age and socioeconomic status. Drinking-water from the reservoir within the mill premises was associated with an increased risk of illness [odds ratio: 26.7, 95% confidence interval (CI) 11.4-62.6) and accounted for most cases (population attributable risk percentage = 82%, 95% CI 70.8-92.9). An outbreak of cholera occurred among workers of the jute mill due to contamination of the drinking-water reservoir. It occurred within a few days of re-opening of the mill after the workers' strike. Health authorities need to enforce disinfection of drinking-water and regularly test its bacteriological quality, particularly before re-opening of the mill after the strike.

Phenotypic and genotypic characterization of Vibrio cholerae clinically isolated in Surabaya, Indonesia

The phenotypic and genotypic characteristics of 6 clinical strains of Vibrio cholerae isolated in Surabaya, Indonesia in 2009 were examined. The DNA fingerprints obtained suggested that these isolates were not from a single clone. Furthermore, all isolates produced cholera toxin and possessed the classical type of toxin B subunit gene, thus meaning that this is the first report of the occurrence of El Tor variants of V. cholerae in Indonesia. Although all isolates were sensitive to almost all antibiotics tested, including ampicillin, chloramphenicol, ciprofloxacin, gentamicin, levofloxacin, kanamycin, nalidixic acid, norfloxacin, streptomycin, trimethoprim-sulfamethoxazole, and tetracycline, and had no mutation in the gyrA and parC genes, they nevertheless possessed the class 1 integron that is a molecular vehicle for the acquisition of antibiotic resistance genes, suggesting that they have the potential to acquire the genetic element for drug resistance.

Phage types of Vibrio cholerae O1 and O139 in the past decade in India

Cholera has been a prevalent disease worldwide since the early 19th century. Vibrio cholerae O1 and O139 are the two serogroups that have been mainly implicated in causing cholera. This study reports the results of biotyping, serotyping and phage typing of V. cholerae O1 and O139 (1998-2007) strains received from different parts of India for the identification of the trends in the occurrence and spread of cholera in the country. However, there has been a notable steep decline in the occurrence of V. cholerae O139 strains over the past few years resulting in no strain of V. cholerae O139 being received from any part of India in 2007 and 2008. Of the total strains received, 79.1% were serotyped as Ogawa and the remaining 20.9% were found to be Inaba, which indicates that Ogawa was the predominant serotype. Almost 100% typeability was observed with the new scheme of V. cholerae O1, with type 27 being the dominant phage type and V. cholerae O139 strains were clustered into the predominant phage type T-1. From the phage typing and serotyping results, it can be concluded that V. cholerae O1 (T-27) and O139 (T-1) strains circulate throughout the country at any given time.