Cholera outbreaks (2012) in three districts of Nepal reveal clonal transmission of multi-drug resistant Vibrio cholerae O1

Cholera rages in Africa and the Middle East: A narrative review on challenges and solutions

Background and Aim

Cholera is a life-threatening infectious disease that is still one of the most common acute watery diarrheal diseases in the world today. Acute diarrhea and severe dehydration brought on by cholera can cause hypovolemic shock, which can be fatal in minutes. Without competent clinical therapy, the rate of case fatality surpasses 50%. The purpose of this review was to highlight cholera challenges in Africa and the Middle East and explain the reasons for why this region is currently a fertile environment for cholera. We investigated cholera serology, epidemiology, and the geographical distribution of cholera in Africa and the Middle East in 2022 and 2023. We reviewed detection methods, such as rapid diagnostic tests (RDTs), and treatments, such as antibiotics and phage therapy. Finally, this review explored oral cholera vaccines (OCVs), and the vaccine shortage crisis.

Methods

We carried out a systematic search in multiple databases, including PubMed, Web of Science, Google Scholar, Scopus, MEDLINE, and Embase, for studies on cholera using the following keywords: ((Cholera) OR (Vibrio cholera) and (Coronavirus) OR (COVID-19) OR (SARS-CoV2) OR (The Middle East) OR (Africa)).

Results and Conclusions

Cholera outbreaks have increased dramatically, mainly in Africa and many Middle Eastern countries. The COVID-19 pandemic has reduced the attention devoted to cholera and disrupted diagnosis and treatment services, as well as vaccination initiatives. Most of the cholera cases in Africa and the Middle East were reported in Malawi and Syria, respectively, in 2022. RDTs are effective in the early detection of cholera epidemics, especially with limited advanced resources, which is the case in much of Africa. By offering both direct and indirect protection, expanding the use of OCV will significantly reduce the burden of current cholera outbreaks in Africa and the Middle East.

Antimicrobial resistance among clinical Vibrio cholerae non-O1/non-O139 isolates: systematic review and meta-analysis

Non-O1/non-O139 Vibrio cholerae (NOVC) are nonpathogenic or asymptomatic colonizers in humans, but they may be related to intestinal or extra-intestinal (severe wound infections or sepsis) infections in immunocompromised patients.The present study aimed to evaluate the weighted pooled resistance (WPR) rates in clinical NOVC isolates based on different years, areas, quality, antimicrobial susceptibility testing (AST), and resistance rates. We systematically searched the articles in PubMed, Scopus, and Embase (until January 2020). Data analyses were performed using the Stata software program (version 17). A total of 16 studies that had investigated 824 clinical NOVC isolates were included in the meta-analysis. The majority of the studies were conducted in Asia (n = 14) and followed by Africa (n = 2). The WPR rates were as follows: erythromycin 10%, ciprofloxacin 5%, cotrimoxazole 27%, and tetracycline 13%. There was an increase in resistance to ciprofloxacin, nalidixic acid, and gentamicin, norfloxacin during the period from 2000 to 2020. On the contrary, there was a decreased resistance to erythromycin, tetracycline, chloramphenicol, cotrimoxazole, ampicillin, streptomycin, kanamycin, and neomycin during the period from 2000 to 2020. The lowest resistance rate were related to gentamicin, kanamycin, ciprofloxacin, and chloramphenicol against NOVC strains. However, temporal changes in antimicrobial resistance rate were found in our study. We established continuous surveillance, careful appropriate AST, and limitations on improper antibiotic usage, which are essential, especially in low-income countries.

Global status of antimicrobial resistance among environmental isolates of Vibrio cholerae O1/O139: a systematic review and meta-analysis

Background

Vibrio cholerae O1/O139 were the predominant circulating serogroups exhibiting multi-drug resistance (MDR) during the cholera outbreak which led to cholera treatment failures.

Objective

This meta-analysis aimed to evaluate the weighted pooled resistance (WPR) rates in V. cholerae O1/O139 isolates obtained from environmental samples.

Methods

We systematically searched the articles in PubMed, Scopus, and Embase (until January 2020). Subgroup analyses were then employed by publication year, geographic areas, and the quality of studies. Statistical analyses were conducted using STATA software (ver. 14.0).

Results

A total of 20 studies investigating 648 environmental V. cholerae O1/O139 isolates were analysed. The majority of the studies were originated from Asia (n = 9). In addition, a large number of studies (n = 15 i.e. 71.4%) included in the meta-analysis revealed the resistance to cotrimoxazole and ciprofloxacin. The WPR rates were as follows: cotrimoxazole 59%, erythromycin 28%, tetracycline 14%, doxycycline 5%, and ciprofloxacin 0%. There was increased resistance to nalidixic acid, cotrimoxazole, furazolidone, and tetracycline while a decreased resistance to amoxicillin, ciprofloxacin, erythromycin, chloramphenicol, ampicillin, streptomycin, and ceftriaxone was observed during the years 2000–2020. A significant decrease in the doxycycline and ciprofloxacin-resistance rates in V. cholerae O1/O139 isolates was reported over the years 2011–2020 which represents a decrease in 2001–2010 (p < 0.05).

Conclusions

Fluoroquinolones, gentamicin, ceftriaxone, doxycycline, kanamycin, and cefotaxime showed the highest effectiveness and the lowest resistance rate. However, the main interest is the rise of antimicrobial resistance in V. cholerae strains especially in low-income countries or endemic areas, and therefore, continuous surveillance, careful appropriate AST, and limitation on improper antibiotic usage are crucial.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01100-3.

Cholera amid COVID-19: Call from three nations; India, Bangladesh, and Nepal

Covid-19 was a major pandemic of the 21st century that flinched away every individual worldwide. The extensive impact of this rapidly spreading deadly virus doomed the health care systems with the unexpected wave wreaked havoc leading to a global health crisis. It has been a high burden on the functioning existing medical system, overloads health professionals, disruption of the medical supply chain. The economy of the nations has been at losses with a significant slowing down in revenue growth over the past 2 years. After taking its toll, drawing away other diseases including cholera. The three developing nations; India, Bangladesh and Nepal, are now at the verge of facing an outbreak of Cholera. It is not surprising to hear cholera in this nation but the fact that its negligence due to Covid-19 pandemic and monkeypox along with a crumbled health system due to the pandemic has made these nations vulnerable for health crisis. Along with this three nations, cholera has made its way to different parts of this globe and it is high time that attention must be drawn towards it as mismanagement could even cause life.

Antimicrobial resistance in Vibrio cholerae O1/O139 clinical isolates: a systematic review and meta-analysis

OBJECTIVES

Vibrio cholerae O1/O139 is responsible for cholera epidemics; that remains a huge public health menace across the globe. Furthermore, an increasing resistance rate among V. cholerae strains has been reported around the world. Therefore, the objective of this meta-analysis was to evaluate the weighted pooled resistance (WPR) rates in clinical V. cholerae O1/O139 isolates based on different years, areas, antimicrobial susceptibility testing, and resistance rates.

RESEARCH DESIGN AND METHODS

: We searched the studies in PubMed, Scopus, Embase, and Web of Science (until January 2020). Statistical analyses were conducted using STATA software (ver. 14.0).

RESULTS

: A total of 139 studies investigating 24062 V. cholerae O1/O139 isolates were analyzed. The majority of the studies originated in Asia (n=102). The WPR rates were as follows: azithromycin 1%, erythromycin 36%, ciprofloxacin 3%, cotrimoxazole 79%, doxycycline 7%, tetracycline 20%. There was increased resistance to cotrimoxazole, ciprofloxacin, and tetracycline during the 1980 to 2020 years.

CONCLUSIONS

: Temporal changes in antibiotic resistance rate found in this study demonstrated the critical continuous surveillance of antibiotic resistance. Also, ciprofloxacin, azithromycin, gentamicin, cephalexin, imipenem, ofloxacin, and norfloxacin were found to be the best antibiotics against V. cholera, with the highest and the lowest effectiveness resistance rate.

Variants of ctxB alleles of Vibrio cholerae O1 caused sequential cholera outbreaks in the tribal areas of Odisha, India

Cholera localized outbreaks/epidemics accounting for high morbidity and mortality have been reported in different years both from the coastal and tribal districts of Odisha. In the present study, the emergence and spread of two sequential cholera outbreaks reported in July to October 2012 from Rayagada and Kalahandi districts of Odisha was investigated. Environmental water samples from different sources and rectal swabs from diarrhoea patients were analysed for identification, antibiogram profiles and molecular studies using DMAMA-PCR assays. The pulsed field gel electrophoresis (PFGE) was done on some selected Vibrio cholerae O1 strains isolated from these cholera outbreak areas. Results showed 42% of rectal swabs and 2.3% of water samples collected from both the districts were positive for Vibrio cholerae O1 Ogawa biotype El Tor carrying both ctxB1 and ctxB7 genotypes. The common resistance profile of V. cholerae O1 strains was ampicillin, nalidixic acid, furazolidone and co-trimoxazole. The PFGE analysis on selected V. cholerae O1 strains of ctxB1 and ctxB7 genotypes showed three pulsotypes with 96% similarity matrix exhibiting the relationship with their respective water sources. Hence, continuous surveillance is highly essential to monitor the antibiogram profile and changing pattern of ctxB genotypes of V. cholerae O1 in this region.

Phylogenetic and antimicrobial drug resistance analysis of Vibrio cholerae O1 isolates from Ghana

We investigated the evolution, phylogeny and antimicrobial resistance of Vibrio cholerae O1 isolates (VCO1) from Ghana. Outbreak and environmental sources of VCO1 were characterized, whole-genome sequenced and compared to globally available seventh pandemic (7P) strains of V. cholerae at SNP resolution. Final analyses included 636 isolates. Novel Ghanaian isolates clustered into three distinct clades (clades 1, 2 and 3) in wave 3 of the 7P lineage. The closest relatives of our novel Ghanaian isolates were from Benin, Cameroon, Togo, Niger and Nigeria. All novel Ghanaian isolates were multi-drug resistant. Environmental isolates clustered into clade 2, despite being isolated years later, showing the possibility of persistence and re-emergence of older clades. A lag phase of several years from estimated introduction to reported cases suggests pathogen persistence in the absence of reported cholera cases. These results highlight the importance of deeper surveillance for understanding transmission routes between bordering countries and planning tailored vaccination campaigns in an effort to eradicate cholera.

Environmental reservoirs of Vibrio cholerae serogroups in the flowing freshwater environs from the tribal areas of Odisha, Eastern India

The environmental reservoirs of different serogroups of Vibrio cholerae causing cholera in the flowing freshwater bodies of the tribal areas of Odisha are not known. So the present study was conducted from June 2017 to March 2020 to find out the environmental reservoirs of V. cholerae serogroups in the water and plankton samples collected from the river, nala, stream and chua from Rayagada district. Similarly, rectal swabs were collected from diarrhoea patients and correlation was established among the V. cholerae strains isolated from diarrhoea patients and environmental V. cholerae isolates through routine culture, different multiplex PCR assays and pulse field gel electrophoresis (PFGE) analysis using standard techniques. The multiplex PCR assays on biotypes and different toxic genes exhibited similar correlation between the clinical and water isolates, which was further strengthened by PFGE analysis. The planktonic DNA was positive for ctxA gene which established that the environmental water bodies were the reservoirs for virulence genes of V. cholerae serogroups. The detection of environmental reservoirs of V. cholerae serogroups in temporarily stagnant condition of water; partially encircled by stones, and near the bank of the river, nala and stream were the reservoirs which is a rare report from Odisha, India and Globe.

Emergence and spread of different ctxB alleles of Vibrio cholerae O1 in Odisha, India

This study reports variants of the ctxB allele of Vibrio cholerae O1 isolated between 1995 and 2019 in Odisha, India. ctxB1 genotypes dominated from 1995 to 2016. The Haitian variant and El Tor ctxB3 genotypes of V. cholerae O1 emerged in 1999, and were most common in 2018-2019 and 2005-2011, respectively. The ctxB7 genotype of the Haitian variant of V. cholerae O1 was quiescent from 2000 to 2006, but further spread was noted from 2007 to 2019.

Evolution, distribution and genetics of atypical Vibrio cholerae - A review

Vibrio cholerae is the etiological agent of cholera, a severe diarrheal disease, which can occur as either an epidemic or sporadic disease. Cholera pandemic-causing V. cholerae O1 and O139 serogroups originated from the Indian subcontinent and spread globally and millions of lives are lost each year, mainly in developing and underdeveloped countries due to this disease. V. cholerae O1 is further classified as classical and El Tor biotype which can produce biotype specific cholera toxin (CT). Since 1961, the current seventh pandemic El Tor strains replaced the sixth pandemic strains resulting in the classical biotype strain that produces classical CT. The ongoing evolution of Atypical El Tor V. cholerae srains encoding classical CT is of global concern. The severity in the pathophysiology of these Atypical El Tor strains is significantly higher than El Tor or classical strains. Pathogenesis of V. cholerae is a complex process that involves coordinated expression of different sets of virulence-associated genes to cause disease. We are yet to understand the complete virulence profile of V. cholerae, including direct and indirect expression of genes involved in its survival and stress adaptation in the host. In recent years, whole genome sequencing has paved the way for better understanding of the evolution and strain distribution, outbreak identification and pathogen surveillance for the implementation of direct infection control measures in the clinic against many infectious pathogens including V. cholerae. This review provides a synopsis of recent studies that have contributed to the understanding of the evolution, distribution and genetics of the seventh pandemic Atypical El Tor V. cholerae strains.

Whole-Genome Analysis of Clinical Vibrio cholerae O1 in Kolkata, India, and Dhaka, Bangladesh, Reveals Two Lineages of Circulating Strains, Indicating Variation in Genomic Attributes

Cholera continues to be a global concern, as large epidemics have occurred recently in Haiti, Yemen, and countries of sub-Saharan Africa. A single lineage of Vibrio cholerae O1 has been considered to be introduced into these regions from South Asia and to cause the spread of cholera. Using genomic epidemiology, we showed that two distinct lineages exist in Bengal, one of which is linked to the global lineage. The other lineage was found only in Iran, Iraq, and countries in Asia and differed from the global lineage regarding cholera toxin variant and drug resistance profile. Therefore, the potential transmission of this lineage to other regions would likely cause worldwide cholera spread and may result in this lineage replacing the current global lineage.

Vibrio cholerae serogroup O1 is responsible for epidemic and pandemic cholera and remains a global public health threat. This organism has been well established as a resident flora of the aquatic environment that alters its phenotypic and genotypic attributes for better adaptation to the environment. To reveal the diversity of clinical isolates of V. cholerae O1 in the Bay of Bengal, we performed whole-genome sequencing of isolates from Kolkata, India, and Dhaka, Bangladesh, collected between 2009 and 2016. Comparison with global isolates by phylogenetic analysis placed the current isolates in two Asian lineages, with lineages 1 and 2 predominant in Dhaka and Kolkata, respectively. Each lineage possessed different genetic traits in the cholera toxin B subunit gene, Vibrio seventh pandemic island II, integrative and conjugative element, and antibiotic-resistant genes. Thus, although recent global transmission of V. cholerae O1 from South Asia has been attributed only to isolates of lineage 2, another distinct lineage exists in Bengal.

Spread of Haitian Variant Vibrio cholerae O1 Causing Cholera Outbreaks in Odisha, India

Cholera posed a significant threat causing outbreaks/epidemics with high morbidity and mortality in Odisha. This study envisages the characterisation of isolated pathogen from two cholera outbreaks reported in 2018 and 2019 from Bargarh and Rayagada districts of Odisha respectively. Vibrio cholerae O1 were isolated following standard techniques. The different virulent and drug resistant genes were detected by multiplex PCR assays; whereas the ctxB genotypes were characterised through double mismatch amplification mutation (DMAMA) PCR assay. The ctxB genes were further sequenced and pulse-field gel electrophoresis (PFGE) was done on some selected strains. The clinical and water isolates of Haitian variant (HCT) V. cholerae O1 Ogawa biotype El Tor with multi drug resistant strains were isolated from both the places. All the V. cholerae O1 strains were positive for virulence genes. The antibiotic resistant genes like dfrA1 (100%), strB (76.9%), intSXT (61.5%) were detected. The PFGE results on V. cholerae O1 strains exhibited two different pulsotypes. These cholera outbreaks were due to multidrug resistant HCT variant V. cholerae O1 strains which were circulating and caused the cholera outbreaks in Odisha. So continuous surveillance on diarrheal disorders is highly essential to prevent the future diarrheal outbreaks in this region.

Characterisation of Vibrio cholerae isolates from the 2009, 2010 and 2016 cholera outbreaks in Lusaka province, Zambia

Introduction

In 2009 and 2010, more than 6,000 cholera cases were recorded during these outbreaks with more than 80% of cases recorded in Lusaka province. After a five-year break, in 2016 an outbreak occurred in Lusaka, causing more than 1,000 cases of cholera. This study will strengthen the epidemiological information on the changing characteristics of the cholera outbreaks, for treatment, prevention and control of the disease.

Methods

This was a laboratory-based descriptive cross-sectional study conducted at the University Teaching Hospital in Lusaka, Zambia. A total of 83 V. cholerae O1 isolates were characterised by biochemical testing, serotyping, antimicrobial susceptibility testing, and macrorestriction analysis using Pulsed-Field Gel Electrophoresis.

Results

Macrorestriction analysis of the isolates demonstrated high genetic diversity among the isolates with 16 different patterns. The largest pattern comprised 9 isolates while the smallest one had 1 isolate. 2009 and 2010 isolates were highly resistant to nalidixic acid and cotrimoxazole, but highly sensitive to azithromycin and ampicillin. Of the fifty-two isolates from the 2016 cholera outbreak, 90% (47) were sensitive to cotrimoxazole, 94% (49) to tetracycline, and 98% (51) to azithromycin, while 98% (51) were resistant to nalidixic acid and 31(60%) to ampicillin.

Conclusion

macrorestriction analysis demonstrated high genetic diversity among the V. cholerae O1 strains, suggesting that these isolates were probably not from a similar source. This study also revealed the emergence of multidrug resistance among the 2016 V. cholerae outbreak isolates but were susceptible to cotrimoxazole, tetracycline, and azithromycin, which can be used for treatment of the cholera cases.

Lessons Learned from Enhancing Sentinel Surveillance for Cholera in Post-Earthquake Nepal in 2016

A major earthquake in 2015 that struck Nepal created a favorable environment for the rapid spread of infectious diseases. In anticipation of a cholera outbreak in 2016, UNICEF, Johns Hopkins University, and the Group for Technical Assistance, Nepal, collaborated to assist the government of Nepal to strengthen early warning surveillance, laboratory-based diagnosis, and field investigation. This article outlines the challenges and lessons learned in cholera prevention and control based on the authors’ experiences in 2016. Priorities for the future plan should include sustaining the enhanced surveillance system for acute gastroenteritis and cholera, rolling out a rapid diagnostic test, and ensuring rapid and systematic epidemiological investigation and environmental testing.

Antibacterial and antibiofilm activity of bone marrow-derived human mesenchymal stem cells secretome against Vibrio cholerae

The ability of V. cholerae to survive and spread in the aquatic environment combined with the scarcity of effective antimicrobial agents, especially those effective against multidrug-resistant strains highlights the need for alternative non-antibiotic approaches for the treatment of V. cholerae infections. The aim of this study was to specifically examine the potential direct effect of unstimulated MSC secretome on V. cholerae killing and biofilm formation as a representative of non-invasive enteric bacterial pathogen. The bmMSCs were characterized by the presence of CD44 and CD73 and the absence of CD45 and CD34 molecular markers. Moreover, self-regeneration and differentiation capacity of MSCs into adipocytes and osteogenic lineages was assessed by immunohistology (IHC) method. The antibacterial activity of unstimulated MSCs supernatant against V. cholerae in broth microdilution assay decreased the bacterial suspension from 10⁸ CFU/ml to 10⁷ CFU/ml and showed a significant antimicrobial activity in a dose-dependent manner at dilutions of 1:8 to 1:128 (P < 0.05). The role of MSC secretome without preconditioning in the prevention of biofilm formation was assessed through plate-crystal violet assay and showed high antibiofilm activity against V. cholerae also in dose-dependent manner. As antibacterial mechanisms of MSC secretome are different from conventional antibiotics, together with its antibiofilm activity, proposes its application as a novel therapeutic approach combatting multi-drug resistant pathogens with no fear of developing antimicrobial resistance.

Diarrheal disease outbreak in Gaidatar village of Rautahat District, Nepal

OBJECTIVE

Diarrheal diseases, including cholera, remain a major public health concern in developing countries like Nepal. This study investigated a diarrheal outbreak that affected over 1500 people in Gaidatar village of Rautahat district in central Nepal and sought to identify the source and causation of the disease. Stool samples were collected from individuals with acute diarrheal illness (n = 16) and healthy non-diarrheal children (n = 39), along with samples from local drinking water sources (n = 8) and their sewage system (n = 10). None of the individuals were sampled multiple times. Diarrheic stool and sewage samples were analysed for the presence of Vibrio cholerae, while coliforms were tested in drinking water samples following standard microbiological protocols. Enteric parasites were tested in both diarrheic and non-diarrheic stool samples.

RESULTS

Vibrio cholerae O1 Ogawa serotype was isolated in 18.7% of the diarrheic stool and 20.0% of the sewage. Coliforms were found in all drinking water samples, with 87.5% testing positive for fecal coliform. Additionally, 43.6% of the stool samples (n = 55) had at least one of the intestinal parasites tested, primarily Giardia lamblia (21.8%). However, almost all parasites were found in non-diarrheal stool. Taken together, our results provide evidence that the diarrheal outbreak was associated with V. cholerae O1 Ogawa serotype, possibly transmitted through the drinking water sources contaminated with fecal matters from their sewage (drainage) system. These findings warrant regular surveillance of drinking water sources to help prevent future outbreaks.

Epidemiological and molecular forensics of cholera recurrence in Haiti

Cholera has affected Haiti with damping waves of outbreaks since October 2010. However, mechanisms behind disease persistence during lull periods remain poorly understood. By mid 2014, cholera transmission seemed to only persist in the northern part of Haiti. Meanwhile, cholera appeared nearly extinct in the capital, Port-au-Prince, where it eventually exploded in September 2014. This study aimed to determine whether this outbreak was caused by local undetected cases or by re-importation of the disease from the north. Applying an integrated approach between November 2013 and November 2014, we assessed the temporal and spatial dynamics of cholera using routine surveillance data and performed population genetics analyses of 178 Vibrio cholerae O1 clinical isolates. The results suggest that the northern part of the country exhibited a persisting metapopulation pattern with roaming oligoclonal outbreaks that could not be effectively controlled. Conversely, undetected and unaddressed autochthonous low-grade transmission persisted in the Port-au-Prince area, which may have been the source of the acute outbreak in late-2014. Cholera genotyping is a simple but powerful tool to adapt control strategies based on epidemic specificities. In Haiti, these data have already yielded significant progress in cholera surveillance, which is a key component of the strategy to eventually eliminate cholera.

Differences in substrate specificity of V. cholerae FabH enzymes suggest new approaches for the development of novel antibiotics and biofuels

Vibrio cholerae, the causative pathogen of the life-threatening infection cholera, encodes two copies of β-ketoacyl-acyl carrier protein synthase III (vcFabH1 and vcFabH2). vcFabH1 and vcFabH2 are pathogenic proteins associated with fatty acid synthesis, lipid metabolism, and potential applications in biofuel production. Our biochemical assays characterize vcFabH1 as exhibiting specificity for acetyl-CoA and CoA thioesters with short acyl chains, similar to that observed for FabH homologs found in most gram-negative bacteria. vcFabH2 prefers medium chain-length acyl-CoA thioesters, particularly octanoyl-CoA, which is a pattern of specificity rarely seen in bacteria. Structural characterization of one vcFabH1 and six vcFabH2 structures determined in either apo form or in complex with acetyl-CoA/octanoyl-CoA indicate that the substrate-binding pockets of vcFabH1 and vcFabH2 are of different sizes, accounting for variations in substrate chain-length specificity. An unusual and unique feature of vcFabH2 is its C-terminal fragment that interacts with both the substrate-entrance loop and the dimer interface of the enzyme. Our discovery of the pattern of substrate specificity of both vcFabH1 and vcFabH2 can potentially aid the development of novel antibacterial agents against V. cholerae. Additionally, the distinctive substrate preference of FabH2 in V. cholerae and related facultative anaerobes conceivably make it an attractive component of genetically engineered bacteria used for commercial biofuel production.

Emergency response in water, sanitation and hygiene to control cholera in post-earthquake Nepal in 2016

After the 2015 earthquake in Nepal that killed approximately 9,000 people, the country faced an increased risk of cholera outbreaks due to extensive destruction of water and sanitation infrastructure and massive displacement. The disaster revealed long-standing weaknesses in water and sanitation systems in the country. Anticipating a cholera outbreak in 2016, UNICEF, Johns Hopkins University, and the Group for Technical Assistance partnered to support the Government of Nepal to ensure a safe water supply and improve sanitation and hygiene. This article discusses challenges, gaps, lessons learned and recommendations that were drawn from the authors' experience in cholera prevention and control in post-earthquake Nepal. Challenges identified include lack of regular water quality testing and monitoring, inconsistent use of point-of-use water treatment products, and lack of a fast-track mechanism for rapid response. The article argues for building a resilient water and sanitation system to secure sustainable and equitable access to safe drinking water.

Analysis of Vibrio seventh pandemic island II and novel genomic islands in relation to attachment sequences among a wide variety of Vibrio cholerae strains

Vibrio cholerae O1 El Tor, the pathogen responsible for the current cholera pandemic, became pathogenic by acquiring virulent factors including Vibrio seventh pandemic islands (VSP)‐I and −II. Diversity of VSP‐II is well recognized; however, studies addressing attachment sequence left (attL) sequences of VSP‐II are few. In this report, a wide variety of V. cholerae strains were analyzed for the structure and distribution of VSP‐II in relation to their attachment sequences. Of 188 V. cholerae strains analyzed, 81% (153/188) strains carried VSP‐II; of these, typical VSP‐II, and a short variant was found in 36% (55/153), and 63% (96/153), respectively. A novel VSP‐II was found in two V. cholerae non‐O1/non‐O139 strains. In addition to the typical 14‐bp attL, six new attL‐like sequences were identified. The 14‐bp attL was associated with VSP‐II in 91% (139/153), whereas the remaining six types were found in 9.2% (14/153) of V. cholerae strains. Of note, six distinct types of the attL‐like sequence were found in the seventh pandemic wave 1 strains; however, only one or two types were found in the wave 2 or 3 strains. Interestingly, 86% (24/28) of V. cholerae seventh pandemic strains harboring a 13‐bp attL‐like sequence were devoid of VSP‐II. Six novel genomic islands using two unique insertion sites to those of VSP‐II were identified in 11 V. cholerae strains in this study. Four of those shared similar gene clusters with VSP‐II, except integrase gene.

Health Problems while Working as a Volunteer or Humanitarian Aid Worker in Post-Earthquake Nepal

INTRODUCTION

Volunteers and humanitarian aid workers working in disaster struck areas of the world are a vulnerable group of travelers. Nepal saw an influx of these humanitarian aid workers following earthquakes in April and May 2015. This study was undertaken to find out the pre-travel preparation and to estimate the risk of disease while the volunteers were deployed in Nepal.

METHODS

This was a descriptive cross-sectional study conducted at CIWEC Hospital located in Kathmandu. A questionnaire was given to all volunteers and aid workers who arrived at the hospital for evaluation of health related problems and agreed to be part of the study.

RESULTS

Ninety-five volunteers were enrolled in the study. Among these, 65 (68%) were female and 30 (32%) were male. The immunizations received before travel were Hepatitis A 82 (86%), Hepatitis B 82 (86%), Typhoid 70 (73%), Rabies 38 (40%), Japanese Encephalitis 34 (36%), Influenza within last one year 23 (24%), measles 48 (51%), Cholera 34 (36%),Tetanus within 10 years 71 (75%) and Varicella 38 (40%). Forty-four (45%) of travelers carried medication for treatment of Traveler's Diarrhea (TD) which included Ciprofloxacin, Azithromycin, Loperamide and others like Metronidazole and Charcoal. The common illnesses encountered were gastrointestinal, skin problems , injury and musculoskeletal problems, respiratory problems, genitourinary problems, cardiovascular, psychological problems, syncope, and miscellaneous.

CONCLUSIONS

Traveler's Diarrhea and dermatological problems were the most common health related problems. Volunteers were not properly prepared for self-treatment and pre-travel preparation was sub-optimal. Important pre travel health advice will decrease the incidence of health problems in this group.

Epidemiology and Antibiogram Profile of Vibrio cholerae Isolates between 2004-2013 from Odisha, India

Cholera is an acute diarrheal disease caused by Vibrio cholerae serogroups O1 and O139, which are known to cause epidemics of cholera in Odisha. The present study was intended to document the antibiotic resistance pattern among clinical isolates of both serogroups of V. cholerae (O1 and O139) isolated during 2004-2013. Nine-hundred nine isolates of V. cholerae were included in this study and were identified by standard procedures. An antibiotic sensitivity test was performed by the disc diffusion method. The seasonality of cholera in this region indicated that there was one peak in the rainy season only. The number of cholera cases started increasing from July and declined starting from the month of October onward. The adult age group of patients was the worst affected among all age groups of patients. The 2 different serogroups of V. cholerae (O1 and O139) showed different prevalence rates (%) of resistance to all the antibiotics in each year. Serogroup O1 showed uniformly high resistance to co-trimoxazole, furazolidone, and nalidixic acid throughout the study. Chloramphenicol encountered resistance only during 2009, but the strains were sensitive in the other years. The emergence of multiple drug-resistant V. cholerae strains may significantly influence the control of future outbreaks and epidemics of cholera in this region.

Antimicrobial Resistance Risks of Cholera Prophylaxis for United Nations Peacekeepers

More than 5 years after a United Nations peacekeeping battalion introduced cholera to Haiti, over 150,000 peacekeepers continue to be deployed annually from countries where cholera is endemic. The United Nations has thus far declined to provide antimicrobial chemoprophylaxis to peacekeepers, a policy based largely on concerns that the risks of drug resistance generation and spread would outweigh the potential benefits of preventing future cholera importations. In this study, we sought to better understand the relative benefits and risks of cholera chemoprophylaxis for peacekeepers in terms of antibiotic resistance. Using a stochastic model to quantify the potential impact of chemoprophylaxis on importation and transmission of drug-resistant and drug-sensitive Vibrio cholerae , we found that chemoprophylaxis would decrease the probability of cholera importation but would increase the expected number of drug-resistant infections if an importation event were to occur. Despite this potential increase, we found that at least 10 drug-sensitive infections would likely be averted per excess drug-resistant infection under a wide range of assumptions about the underlying prevalence of drug resistance and risk of acquired resistance. Given these findings, policymakers should reconsider whether the potential resistance risks of providing antimicrobial chemoprophylaxis to peacekeepers are sufficient to outweigh the anticipated benefits.

Vibrio cholerae O1 with Reduced Susceptibility to Ciprofloxacin and Azithromycin Isolated from a Rural Coastal Area of Bangladesh

Cholera outbreaks occur each year in the remote coastal areas of Bangladesh and epidemiological surveillance and routine monitoring of cholera in these areas is challenging. In this study, a total of 97 Vibrio cholerae O1 isolates from Mathbaria, Bangladesh, collected during 2010 and 2014 were analyzed for phenotypic and genotypic traits, including antimicrobial susceptibility. Of the 97 isolates, 95 possessed CTX-phage mediated genes, ctxA, ace, and zot, and two lacked the cholera toxin gene, ctxA. Also both CTX⁺ and CTX⁻V. cholerae O1 isolated in this study carried rtxC, tcpA^ET, and hlyA. The classical cholera toxin gene, ctxB1, was detected in 87 isolates, while eight had ctxB7. Of 95 CTX⁺V. cholerae O1, 90 contained rstR^ET and 5 had rstR^CL. All isolates, except two, contained SXT related integrase intSXT. Resistance to penicillin, streptomycin, nalidixic acid, sulfamethoxazole-trimethoprim, erythromycin, and tetracycline varied between the years of study period. Most importantly, 93% of the V. cholerae O1 were multidrug resistant. Six different resistance profiles were observed, with resistance to streptomycin, nalidixic acid, tetracycline, and sulfamethoxazole-trimethoprim predominant every year. Ciprofloxacin and azithromycin MIC were 0.003–0.75 and 0.19–2.00 μg/ml, respectively, indicating reduced susceptibility to these antibiotics. Sixteen of the V. cholerae O1 isolates showed higher MIC for azithromycin (≥0.5 μg/ml) and were further examined for 10 macrolide resistance genes, erm(A), erm(B), erm(C), ere(A), ere(B), mph(A), mph(B), mph(D), mef(A), and msr(A) with none testing positive for the macrolide resistance genes.

Characterization and Genetic Variation of Vibrio cholerae Isolated from Clinical and Environmental Sources in Thailand

Cholera is still an important public health problem in several countries, including Thailand. In this study, a collection of clinical and environmental V. cholerae serogroup O1, O139, and non-O1/non-O139 strains originating from Thailand (1983 to 2013) was characterized to determine phenotypic and genotypic traits and to investigate the genetic relatedness. Using a combination of conventional methods and whole genome sequencing (WGS), 78 V. cholerae strains were identified. WGS was used to determine the serogroup, biotype, virulence, mobile genetic elements, and antimicrobial resistance genes using online bioinformatics tools. In addition, phenotypic antimicrobial resistance was determined by the minimal inhibitory concentration (MIC) test. The 78 V. cholerae strains belonged to the following serogroups O1: (n = 44), O139 (n = 16) and non-O1/non-O139 (n = 18). Interestingly, we found that the typical El Tor O1 strains were the major cause of clinical cholera during 1983–2000 with two Classical O1 strains detected in 2000. In 2004–2010, the El Tor variant strains revealed genotypes of the Classical biotype possessing either only ctxB or both ctxB and rstR while they harbored tcpA of the El Tor biotype. Thirty O1 and eleven O139 clinical strains carried CTXϕ (Cholera toxin) and tcpA as well four different pathogenic islands (PAIs). Beside non-O1/non-O139, the O1 environmental strains also presented chxA and Type Three Secretion System (TTSS). The in silico MultiLocus Sequence Typing (MLST) discriminated the O1 and O139 clinical strains from other serogroups and environmental strains. ST69 was dominant in the clinical strains belonging to the 7^th pandemic clone. Non-O1/non-O139 and environmental strains showed various novel STs indicating genetic variation. Multidrug-resistant (MDR) strains were observed and conferred resistance to ampicillin, azithromycin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim and harboured variants of the SXT elements.

For the first time since 1986, the presence of V. cholerae O1 Classical was reported causing cholera outbreaks in Thailand. In addition, we found that V. cholerae O1 El Tor variant and O139 were pre-dominating the pathogenic strains in Thailand. Using WGS and bioinformatic tools to analyze both historical and contemporary V. cholerae circulating in Thailand provided a more detailed understanding of the V. cholerae epidemiology, which ultimately could be applied for control measures and management of cholera in Thailand.

Unique Clones of Vibrio cholerae O1 El Tor with Haitian Type ctxB Allele Implicated in the Recent Cholera Epidemics from Nigeria, Africa

Background and Objectives

The antimicrobial susceptibility patterns and genetic characteristics of Vibrio cholerae O1, which is responsible for several cholera epidemics in Nigeria, are not reported in detail since 2007. In this study, we screened V. cholerae O1 El Tor biotype isolates from cholera cases and water samples from different states to investigate their phenotypic and genetic attributes with special reference to their clonality.

Results

All the V. cholerae O1 biotype El Tor isolates isolated during 2007–2013 were susceptible to fluoroquinolones and tetracycline, the drugs currently used in the treatment of cholera cases in Nigeria. Emergence of CT genotype 7 (Haitian type of ctxB allele) was predominantly seen among Ogawa serotype and the CT genotype 1 (classical ctxB allele) was mostly found in Inaba serotype. Overall, V. cholerae O1 from clinical and water samples were found to be closely related as determined by the pulsed-field gel electrophoresis. V. cholerae isolates from Abia, Kano and Bauchi were found to be genetically distinct from the other states of Nigeria.

Conclusion

Fecal contamination of the water sources may be the possible source of the cholera infection. Combined prevalence of Haitian and classical ctxB alleles were detected in Ogawa and Inaba serotypes, respectively. This study further demonstrated that V. cholerae O1 with the ctxB has been emerged similar to the isolates reported in Haiti. Our findings suggest that the use of fluoroquinolones or tetracycline/doxycycline may help in the effective management of acute cholera in the affected Nigerian states. In addition, strengthening the existing surveillance in the hospitals of all the states and supply of clean drinking water may control cholera outbreaks in the future.

Multidrug resistant Vibrio cholerae O1 from clinical and environmental samples in Kathmandu city

Background

Cholera, an infectious disease caused by Vibrio cholerae, is a major public health problem and is a particularly burden in developing countries including Nepal. Although the recent worldwide outbreaks of cholera have been due to V. cholerae El Tor, the classical biotypes are still predominant in Nepal. Serogroup O1 of the V. cholerae classical biotype was the primary cause of a cholera outbreak in Kathmandu in 2012. Thus, this study was designed to know serotypes and biotypes of V. cholerae strains causing recent outbreak with reference to drug resistant patterns. Moreover, we also report the toxigenic strains of V. cholerae from both environmental and clinical specimens by detecting the ctx gene.

Methods

Twenty four V. cholerae (n = 22 from stool samples and n = 2 from water samples) isolated in this study were subjected to Serotyping and biotyping following the standard protocols as described previously. All of the isolates were tested for antimicrobial susceptibility patterns using the modified Kirby-Bauer disk diffusion method as recommended by CLSI guidelines. The screening of the ctx genes (ctxA2-B gene) were performed by PCR method using a pair of primers; C2F (5′-AGGTGTAAAATTCCTTGACGA-3′) and C2R (5′-TCCTCAGGGTATCCTTCATC-3′) to identify the toxigenic strains of V. cholerae.

Results

Among twenty four V. cholerae isolates, 91.7% were clinical and 8.3% were from water samples. Higher rate of V. cholerae infection was found among adults of aged group 20–30 years. All isolates were serogroups O1 of the V. cholerae classical biotype and sub serotype, Ogawa. All isolates were resistant to ampicillin, nalidixic acid and cotrimoxazole. 90.9% were resistant to erythromycin however, tetracycline was found to be the most effective drug for the isolates. All isolates were multidrug resistant (MDR) and possessed a ctx gene of approximately 400 base pairs indicating the toxigenic strains.

Conclusion

Hundred percent strains of V. cholerae were MDR possessing a ctx gene. It suggests that toxigenic strains be identified and proper antibiotic susceptibility testing be conducted. This will allow effective empirical therapy to be used to treat and control cholera.