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Efficacy of a single-dose regimen of inactivated whole-cell oral cholera vaccine: results from 2 years of follow-up of a randomised trial.

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Efficacy of a single-dose regimen of inactivated whole-cell oral cholera vaccine: results from 2 years of follow-up of a randomised trial.

Lancet Infect Dis. 2018 06;18(6):666-674

Authors: Qadri F, Ali M, Lynch J, Chowdhury F, Khan AI, Wierzba TF, Excler JL, Saha A, Islam MT, Begum YA, Bhuiyan TR, Khanam F, Chowdhury MI, Khan IA, Kabir A, Riaz BK, Akter A, Khan A, Asaduzzaman M, Kim DR, Siddik AU, Saha NC, Cravioto A, Singh AP, Clemens JD

Abstract
BACKGROUND: A single-dose regimen of inactivated whole-cell oral cholera vaccine (OCV) is attractive because it reduces logistical challenges for vaccination and could enable more people to be vaccinated. Previously, we reported the efficacy of a single dose of an OCV vaccine during the 6 months following dosing. Herein, we report the results of 2 years of follow-up.
METHODS: In this placebo-controlled, double-blind trial done in Dhaka, Bangladesh, individuals aged 1 year or older with no history of receipt of OCV were randomly assigned to receive a single dose of inactivated OCV or oral placebo. The primary endpoint was a confirmed episode of non-bloody diarrhoea for which the onset was at least 7 days after dosing and a faecal culture was positive for Vibrio cholerae O1 or O139. Passive surveillance for diarrhoea was done in 13 hospitals or major clinics located in or near the study area for 2 years after the last administered dose. We assessed the protective efficacy of the OCV against culture-confirmed cholera occurring 7-730 days after dosing with both crude and multivariable per-protocol analyses. This trial is registered at ClinicalTrials.gov, number NCT02027207.
FINDINGS: Between Jan 10, 2014, and Feb 4, 2014, 205 513 people were randomly assigned to receive either vaccine or placebo, of whom 204 700 (102 552 vaccine recipients and 102 148 placebo recipients) were included in the per-protocol analysis. 287 first episodes of cholera (109 among vaccine recipients and 178 among placebo recipients) were detected during the 2-year follow-up; 138 of these episodes (46 in vaccine recipients and 92 in placebo recipients) were associated with severe dehydration. The overall incidence rates of initial cholera episodes were 0·22 (95% CI 0·18 to 0·27) per 100 000 person-days in vaccine recipients versus 0·36 (0·31 to 0·42) per 100 000 person-days in placebo recipients (adjusted protective efficacy 39%, 95% CI 23 to 52). The overall incidence of severe cholera was 0·09 (0·07 to 0·12) per 100 000 person-days versus 0·19 (0·15 to 0·23; adjusted protective efficacy 50%, 29 to 65). Vaccine protective efficacy was 52% (8 to 75) against all cholera episodes and 71% (27 to 88) against severe cholera episodes in participants aged 5 years to younger than 15 years. For participants aged 15 years or older, vaccine protective efficacy was 59% (42 to 71) against all cholera episodes and 59% (35 to 74) against severe cholera. The protection in the older age groups was sustained throughout the 2-year follow-up. In participants younger than 5 years, the vaccine did not show protection against either all cholera episodes (protective efficacy -13%, -68 to 25) or severe cholera episodes (-44%, -220 to 35).
INTERPRETATION: A single dose of the inactivated whole-cell OCV offered protection to older children and adults that was sustained for at least 2 years. The absence of protection of young children might reflect a lesser degree of pre-existing natural immunity in this age group.
FUNDING: Bill & Melinda Gates Foundation to the International Vaccine Institute.

PMID: 29550406 [PubMed - indexed for MEDLINE]

Feasibility of a Comprehensive Targeted Cholera Intervention in The Kathmandu Valley, Nepal.

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Feasibility of a Comprehensive Targeted Cholera Intervention in The Kathmandu Valley, Nepal.

Am J Trop Med Hyg. 2019 Mar 18;:

Authors: Roskosky M, Acharya B, Shakya G, Karki K, Sekine K, Bajracharya D, von Seidlein L, Devaux I, Lopez AL, Deen J, Sack DA

Abstract
A comprehensive targeted intervention (CTI) was designed and deployed in the neighborhoods of cholera cases in the Kathmandu Valley with the intent of reducing rates among the neighbors of the case. This was a feasibility study to determine whether clinical centers, laboratories, and field teams were able to mount a rapid, community-based response to a case within 2 days of hospital admission. Daily line listings were requested from 15 participating hospitals during the monsoon season, and a single case initiated the CTI. A standard case definition was used: acute watery diarrhea, with or without vomiting, in a patient aged 1 year or older. Rapid diagnostic tests and bacterial culture were used for confirmation. The strategy included household investigation of cases; water testing; water, sanitation, and hygiene (WASH) intervention; and health education. A CTI coverage survey was conducted 8 months postintervention. From June to December of 2016, 169 cases of Vibrio cholerae O1 were confirmed by bacterial culture. Average time to culture result was 3 days. On average, the CTI Rapid Response Team (RRT) was able to visit households 1.7 days after the culture result was received from the hospital (3.9 days from hospital admission). Coverage of WASH and health behavior messaging campaigns were 30.2% in the target areas. Recipients of the intervention were more likely to have knowledge of cholera symptoms, treatment, and prevention than non-recipients. Although the RRT were able to investigate cases at the household within 2 days of a positive culture result, the study identified several constraints that limited a truly rapid response.

PMID: 30887946 [PubMed - as supplied by publisher]

Cholera epidemic in Yemen.

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Cholera epidemic in Yemen.

Lancet Glob Health. 2018 12;6(12):e1283

Authors: Dureab F, Shibib K, Yé Y, Jahn A, Müller O

PMID: 30316747 [PubMed - indexed for MEDLINE]

Cholera epidemic in Yemen - Author's reply.

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Cholera epidemic in Yemen - Author's reply.

Lancet Glob Health. 2018 12;6(12):e1284-e1285

Authors: Camacho A, Bouhenia M, Azman AS, Poncin M, Zagaria N, Luquero FJ

PMID: 30316746 [PubMed - indexed for MEDLINE]

Oral cholera vaccine coverage during a preventive door-to-door mass vaccination campaign in Nampula, Mozambique.

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Oral cholera vaccine coverage during a preventive door-to-door mass vaccination campaign in Nampula, Mozambique.

PLoS One. 2018;13(10):e0198592

Authors: Semá Baltazar C, Rafael F, Langa JPM, Chicumbe S, Cavailler P, Gessner BD, Pezzoli L, Barata A, Zaina D, Inguane DL, Mengel MA, Munier A

Abstract
BACKGROUND: In addition to improving water, sanitation and hygiene (WASH) measures and optimal case management, the introduction of Oral cholera vaccine (OCV) is a complementary strategy for cholera prevention and control for vulnerable population groups. In October 2016, the Mozambique Ministry of Health implemented a mass vaccination campaign using a two-dose regimen of the Shanchol™ OCV in six high-risk neighborhoods of Nampula city, in Northern Mozambique. Overall 193,403 people were targeted by the campaign, which used a door-to-door strategy. During campaign follow-up, a population survey was conducted to assess: (1) OCV coverage; (2) frequency of adverse events following immunization; (3) vaccine acceptability and (4) reasons for non-vaccination.
METHODOLOGY/PRINCIPAL FINDINGS: In the absence of a household listing and clear administrative neighborhood delimitations, we used geospatial technology to select households from satellite images and used the support of community leaders. One person per household was randomly selected for interview. In total, 636 individuals were enrolled in the survey. The overall vaccination coverage with at least one dose (including card and oral reporting) was 69.5% (95%CI: 51.2-88.2) and the two-dose coverage was 51.2% (95%CI: 37.9-64.3). The campaign was well accepted. Among the 185 non-vaccinated individuals, 83 (44.6%) did not take the vaccine because they were absent when the vaccination team visited their houses. Among the 451 vaccinated individuals, 47 (10%) reported minor and non-specific complaints, and 78 (17.3%) mentioned they did not receive any information before the campaign.
CONCLUSIONS/SIGNIFICANCE: In spite of overall coverage being slightly lower than expected, the use of a mobile door-to-door strategy remains a viable option even in densely-populated urban settings. Our results suggest that campaigns can be successfully implemented and well accepted in Mozambique in non-emergency contexts in order to prevent cholera outbreaks. These findings are encouraging and complement the previous Mozambican experience related to OCV.

PMID: 30281604 [PubMed - indexed for MEDLINE]

Challenges for programmatic implementation of killed whole cell oral cholera vaccines for prevention and control of cholera: a meta-opinion.

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Challenges for programmatic implementation of killed whole cell oral cholera vaccines for prevention and control of cholera: a meta-opinion.

Expert Opin Biol Ther. 2018 09;18(9):983-988

Authors: Chatterjee P, Kanungo S, Dutta S

Abstract
INTRODUCTION: Cholera remains a public health threat. The development of safe, effective, easy-to-administer, heat-stable, and cheap killed whole cell oral cholera vaccines (OCVs) has provided an additional tool to counter cholera. In this meta-opinion, we review the challenges of delivering OCVs through the existing public health infrastructure in vulnerable areas. Areas covered: We provide an overview of the available vaccines against cholera, the existing evidence about the effectiveness of a two-dose as well as a single-dose OCV strategy. We also highlight the experience from the public health campaigns for OCV deployment. Expert opinion: Several public health experiences have shown the feasibility of incorporating OCVs into the public health response against cholera. Combined with a comprehensive water, sanitation, and hygiene (WaSH) improvement plan, OCVs need to be deployed in identified vulnerable areas, targeting the highest risk groups first. Vaccination programs should not be deployed in lieu of investments in WaSH services, but as a complimentary service in a comprehensive, cholera control intervention package. It has been a challenge to have high two-dose coverage across all eligible recipients, necessitating the adoption of innovative strategies to boost coverage. Longer intervals between doses may help to overcome resource and logistical limitations enabling higher coverage.

PMID: 30107757 [PubMed - indexed for MEDLINE]

Influences of heatwave, rainfall, and tree cover on cholera in Bangladesh.

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Influences of heatwave, rainfall, and tree cover on cholera in Bangladesh.

Environ Int. 2018 11;120:304-311

Authors: Wu J, Yunus M, Ali M, Escamilla V, Emch M

Abstract
Cholera is a severe diarrheal disease and remains a global threat to public health. Climate change and variability have the potential to increase the distribution and magnitude of cholera outbreaks. However, the effect of heatwave on the occurrence of cholera at individual level is still unclear. It is also unknown whether the local vegetation could potentially mitigate the effects of extreme heat on cholera outbreaks. In this study, we designed a case-crossover study to examine the association between the risk of cholera and heatwaves as well as the modification effects of rainfall and tree cover. The study was conducted in Matlab, a cholera endemic area of rural Bangladesh, where cholera case data were collected between January 1983 and April 2009. The association between the risk of cholera and heatwaves was examined using conditional logistic regression models. The results showed that there was a higher risk of cholera two days after heatwaves (OR = 1.53, 95% CI: 1.07-2.19) during wet days (rainfall > 0 mm). For households with less medium-dense tree cover, the heatwave after a 2-day lag was positively associated (OR = 1.80, 95% CI: 1.01-3.22) with the risk of cholera during wet days. However, for households with more medium-dense tree cover, the association between the risk of cholera and heatwave in 2-day lag was not significant. These findings suggest that heatwaves might promote the occurrence of cholera, while this relationship was modified by rainfall and tree cover. Further investigations are needed to explore major mechanisms underlying the association between heatwaves and cholera as well as the beneficial effects of tree cover.

PMID: 30107291 [PubMed - indexed for MEDLINE]

Investigating a cholera outbreak in Kaiso Fishing Village, Hoima District, Uganda, October 2015.

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Investigating a cholera outbreak in Kaiso Fishing Village, Hoima District, Uganda, October 2015.

Pan Afr Med J. 2018;30(Suppl 1):14

Authors: Okuga M, Oguttu DW, Okullo AE, Park MM, Ko CP, Frimpong JA, Zhu BP, Ario AR

Abstract
Globally, even though improvements have been made to effective surveillance and response, communicable diseases such as cholera remain high priorities for national health programs, especially in Africa. High-quality surveillance information coupled with adequate laboratory facilities are effective in curbing outbreaks from such diseases, ultimately reducing morbidity and mortality. One way of building this capacity is through simulation of response to such health events. This case study based on a cholera outbreak investigated by FETP trainees in October 2015 in Uganda can be used to reinforce skills of frontline FETP trainees and other novice public health practitioners through a practical simulation approach. This activity should be completed in 2.5 hours.

PMID: 30858918 [PubMed - in process]

Cholera outbreak in a fishing village in Uganda: a case study.

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Cholera outbreak in a fishing village in Uganda: a case study.

Pan Afr Med J. 2018;30(Suppl 1):8

Authors: Zhu BP, Pande G, Kwesiga B, Ario AR

Abstract
In June 2015, the District Health Officer of Kasese District, southwestern Uganda reported an outbreak of cholera in a fishing village. Two fellows of the Uganda Public Health Fellowship Program - Field Epidemiology Track conducted an investigation to verify the existence of an outbreak, determine the mode of transmission, and recommend control measures. This case study describes that investigation, which teaches the steps in an outbreak investigation and the details in each step, what needs to be done in each step to achieve the objectives of the investigation, and what might be the common pitfalls during an outbreak investigation. This case study can be used to teach the fundamental principles of an outbreak investigation and use of Epi Info for outbreak analysis. The audience are field epidemiologists at various levels in different settings.

PMID: 30858912 [PubMed - in process]

Evaluation of the SD bioline cholera rapid diagnostic test during the 2016 cholera outbreak in Lusaka, Zambia.

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Evaluation of the SD bioline cholera rapid diagnostic test during the 2016 cholera outbreak in Lusaka, Zambia.

Trop Med Int Health. 2018 08;23(8):834-840

Authors: Mwaba J, Ferreras E, Chizema-Kawesa E, Mwimbe D, Tafirenyika F, Rauzier J, Blake A, Rakesh A, Poncin M, Stoitsova S, Kwenda G, Azman AS, Chewe O, Serafini M, Lukwesa-Musyani C, Cohuet S, Quilici ML, Luquero FJ, Page AL

Abstract
OBJECTIVE: To assess the performance of the SD Bioline Cholera Ag O1/O139 rapid diagnostic test (RDT) compared to a reference standard combining culture and PCR for the diagnosis of cholera cases during an outbreak.
METHODS: RDT and bacterial culture were performed on site using fresh stools collected from cholera suspected cases, and from stools enriched in alkaline peptone water. Dried stool samples on filter paper were tested for V. cholerae by PCR in Lusaka (as part of a laboratory technology transfer project) and at a reference laboratory in Paris, France. A sample was considered positive for cholera by the reference standard if any of the culture or PCR tests was positive for V. cholerae O1 or O139.
RESULTS: Among the 170 samples tested with SD Bioline and compared to the reference standard, the RDT showed a sensitivity of 90.9% (95% CI: 81.3-96.6) and specificity of 95.2% (95% CI: 89.1-98.4). After enrichment, the sensitivity was 95.5% (95% CI: 87.3-99.1) and specificity 100% (95% CI: 96.5-100).
CONCLUSION: The observed sensitivity and specificity were within recommendations set by the Global Task Force for Cholera Control on the use of cholera RDT (sensitivity = 90%; specificity = 85%). Although the sample size was small, our findings suggest that the SD Bioline RDT could be used in the field to rapidly alert public health officials to the likely presence of cholera cases when an outbreak is suspected.

PMID: 29851181 [PubMed - indexed for MEDLINE]

Cholera Outbreak in Gaidataar: A Lesson for Further Strengthening the Task Force for Epidemic Management in Nepal.

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Cholera Outbreak in Gaidataar: A Lesson for Further Strengthening the Task Force for Epidemic Management in Nepal.

JNMA J Nepal Med Assoc. 2017 Jul-Sep;56(207):374-6

Authors: Yadav S

Abstract
Cholera is an acute enteric infection caused by the ingestion of bacterium Vibrio cholerae(1). Cholera is transmitted through contaminated food and water. Prevention and preparedness of cholera require a coordinated multi-disciplinary approach. The extremely short incubation period enhances the potentially explosive pattern of outbreaks. Cholera can lead to severe dehydration and death if left untreated. The laboratory testing is required for antimicrobial sensitivity testing and for confirming the end of an outbreak. Provision of safe drinking water, proper sanitation, and food safety are critical for preventing occurrence of cholera. Health education aims at communities adopting preventive behavior for averting contamination. Specific training for all the staffs about proper case management including avoidance of noso-comial infection (like face masks, gloves, antiseptic solution, hand scrubs). Sufficient pre-positioned medical supplies for case management (diarrhoeal disease kits, iv fluids, antibiotics, safety measures). Improved access to water, effective sanitation, proper waste management and vector control. Improved communication and public information. Oral Rehydration Salts can treat 80% of cholera1. Appropriate antibiotics can reduce the duration of purging. With a well and properly managed team of health experts with all essential medicines and a good rapid response team, any outbreak can be prevented, controlled and managed.

PMID: 29255324 [PubMed - indexed for MEDLINE]

Piloting a participatory, community-based health information system for strengthening community-based health services: findings of a cluster-randomized controlled trial in the slums of Freetown, Sierra Leone.

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Piloting a participatory, community-based health information system for strengthening community-based health services: findings of a cluster-randomized controlled trial in the slums of Freetown, Sierra Leone.

J Glob Health. 2019 Jun;9(1):010418

Authors: O'Connor EC, Hutain J, Christensen M, Kamara MS, Conteh A, Sarriot E, Samba TT, Perry HB

Abstract
Background: Although community engagement has been promoted as a strategy for health systems strengthening, there is need for more evidence for effectiveness of this approach. We describe an operations research (OR) Study and assessment of one form of community engagement, the development and implementation of a participatory community-based health information system (PCBHIS), in slum communities in Freetown, Sierra Leone.
Methods: A child survival project was implemented in 10 slum communities, which were then randomly allocated to intervention (PCBHIS) and comparison areas. In the 5 PCBHIS communities, the findings from monthly reports submitted by community health workers (CHWs) and verbal autopsy findings for deaths of children who died before reaching 5 years of age, were processed and shared at bimonthly meetings in each community. These meetings, called Community Health Data Review (CHDR) meetings, were attended by community leaders, including members of the Ward Development Committee (WDC) and Health Management Committee (HMC), by the CHW Peer Supervisors, and by representatives of the Peripheral Health Unit. Following a review of the information, attendees proposed actions to strengthen community-based health services in their community. These meetings were held over a period of 20 months from July 2015 to March 2017. At baseline and endline, knowledge, practice and coverage (KPC) surveys measured household health-related behaviors and care-seeking behaviors. The capacity of HMCs and WDCs to engage with the local health system was also measured at baseline and endline. Reports of CHW household contact and assessments of CHW quality were obtained in the endline KPC household survey, and household contacts measured in monthly submitted reports were also tabulated.
Results: The self-assessment scores of WDCs' capacity to fulfil their roles improved more in the intervention than in the comparison area for all six components, but for only 1 of the 6 was the improvement statistically significant (monthly and quarterly meetings in which Peer Supervisor and/or CHW supervision was an agenda item). The scores for the HMCs improved less in the intervention area than in the comparison area for all six components, but none of these differences were statistically significant. Topics of discussion in CHDRs focused primarily on CHW functionality. All three indicators of CHW functioning (as measured by reports submitted from CHWs) improved more in the intervention area relative to the comparison area, with 2 out of 3 measures of improvement reaching statistical significance. Five of 7 household behaviors judged to be amenable to promotion by CHWs improved more in the intervention area than in the comparison area, and 2 out of the 5 were statistically significant (feeding colostrum and appropriate infant and young child feeding). Four of the 6 care-seeking behaviors judged to be amenable to promotion by CHWs improved more in the intervention area than in the comparison area, and 1 was statistically significant (treatment of diarrhea with ORS and zinc). None of the findings that favored the comparison area were statistically significant.
Conclusions: This study was implemented in challenging circumstances. The OR Study intervention was delayed because of interruptions in finalizing the national CHW policy, two separate cholera epidemics, and the Ebola epidemic lasting more than 2 years. Weaknesses in the CHW intervention severely limited the extent to which the PCBHIS could be used to observe trends in mortality and morbidity. Nonetheless, the positive results achieved in the area of functionality of the CHW intervention and community structure capacity are encouraging. Results suggest there is value in further methodologically rigorous investigations into improving community-based health system functioning through a similar approach to community engagement.

PMID: 30842881 [PubMed - indexed for MEDLINE]

Analysis of 19 Highly Conserved Vibrio cholerae Bacteriophages Isolated from Environmental and Patient Sources Over a Twelve-Year Period.

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Analysis of 19 Highly Conserved Vibrio cholerae Bacteriophages Isolated from Environmental and Patient Sources Over a Twelve-Year Period.

Viruses. 2018 06 01;10(6):

Authors: Angermeyer A, Das MM, Singh DV, Seed KD

Abstract
The Vibrio cholerae biotype "El Tor" is responsible for all of the current epidemic and endemic cholera outbreaks worldwide. These outbreaks are clonal, and it is hypothesized that they originate from the coastal areas near the Bay of Bengal, where the lytic bacteriophage ICP1 (International Centre for Diarrhoeal Disease Research, Bangladesh cholera phage 1) specifically preys upon these pathogenic outbreak strains. ICP1 has also been the dominant bacteriophage found in cholera patient stools since 2001. However, little is known about the genomic differences between the ICP1 strains that have been collected over time. Here, we elucidate the pan-genome and the phylogeny of the ICP1 strains by aligning, annotating, and analyzing the genomes of 19 distinct isolates that were collected between 2001 and 2012. Our results reveal that the ICP1 isolates are highly conserved and possess a large core-genome as well as a smaller, somewhat flexible accessory-genome. Despite its overall conservation, ICP1 strains have managed to acquire a number of unknown genes, as well as a CRISPR-Cas system which is known to be critical for its ongoing struggle for co-evolutionary dominance over its host. This study describes a foundation on which to construct future molecular and bioinformatic studies of these V. cholerae-associated bacteriophages.

PMID: 29857590 [PubMed - indexed for MEDLINE]

Long-term effectiveness of one and two doses of a killed, bivalent, whole-cell oral cholera vaccine in Haiti: an extended case-control study.

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Long-term effectiveness of one and two doses of a killed, bivalent, whole-cell oral cholera vaccine in Haiti: an extended case-control study.

Lancet Glob Health. 2018 09;6(9):e1028-e1035

Authors: Franke MF, Ternier R, Jerome JG, Matias WR, Harris JB, Ivers LC

Abstract
BACKGROUND: No study of long-term protection following killed oral cholera vaccination has been done outside of the historically cholera-endemic areas of south Asia, or has examined protection after a single-dose vaccination regimen. To address this, we examined the duration of protection of the standard two-dose regimen and an incomplete regimen of one dose up to 4 years after vaccination in Haiti.
METHODS: In the setting of two-dose vaccination campaigns with a killed, bivalent, whole-cell oral cholera vaccination, we did a case-control study from October, 2012 through November, 2016. Eligible participants were required to be resident in the vaccine catchment area (Artibonite Department or Central Department) where they were recruited at the start of the study; and be eligible for the vaccination campaign (ie, aged ≥12 months, not pregnant, and living in the region at the time of the vaccine campaign). Patients with cholera had a positive stool culture and were recruited from cholera treatment centres. Community controls were matched to people with cholera by age group, time, and neighbourhood. We did adjusted matched regression analyses to calculate vaccine effectiveness and examine heterogeneity in effectiveness over time. The primary outcome was the effectiveness of one and two oral cholera doses as compared with zero doses from 2 months to 48 months after vaccination, measured by self reporting.
FINDINGS: Among 178 people assigned to the case group and 706 people assigned to the control group, we found no evidence that two-dose effectiveness decreased during follow-up. In adjusted analyses, the average cumulative 4 year effectiveness for two doses was 76% (95% CI 59-86). In contrast, single-dose effectiveness decreased over time in a log-linear fashion, with a predicted vaccine effectiveness of 79% at the end of 12 months (95% CI 43-93), which declined to zero before the end of the second year.
INTERPRETATION: In a setting of epidemic and newly endemic cholera in Haiti, single-dose vaccination with killed, bivalent, whole-cell oral cholera vaccination provided short-term protection; however, vaccination with two doses was required for long-term protection, which lasted up to 4 years after vaccination. These results add to the evidence in support of the use of killed, bivalent, whole-cell oral cholera vaccination as part of comprehensive cholera control plans.
FUNDING: US National Institute of Allergy and Infectious Diseases of the National Institutes of Health and the Bill & Melinda Gates Foundation.

PMID: 30103980 [PubMed - indexed for MEDLINE]

Rainfall as a driver of epidemic cholera: Comparative model assessments of the effect of intra-seasonal precipitation events.

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Rainfall as a driver of epidemic cholera: Comparative model assessments of the effect of intra-seasonal precipitation events.

Acta Trop. 2019 Feb;190:235-243

Authors: Lemaitre J, Pasetto D, Perez-Saez J, Sciarra C, Wamala JF, Rinaldo A

Abstract
The correlation between cholera epidemics and climatic drivers, in particular seasonal tropical rainfall, has been studied in a variety of contexts owing to its documented relevance. Several mechanistic models of cholera transmission have included rainfall as a driver by focusing on two possible transmission pathways: either by increasing exposure to contaminated water (e.g. due to worsening sanitary conditions during water excess), or water contamination by freshly excreted bacteria (e.g. due to washout of open-air defecation sites or overflows). Our study assesses the explanatory power of these different modeling structures by formal model comparison using deterministic and stochastic models of the type susceptible-infected-recovered-bacteria (SIRB). The incorporation of rainfall effects is generalized using a nonlinear function that can increase or decrease the relative importance of the large precipitation events. Our modelling framework is tested against the daily epidemiological data collected during the 2015 cholera outbreak within the urban context of Juba, South Sudan. This epidemic is characterized by a particular intra-seasonal double peak on the incidence in apparent relation with particularly strong rainfall events. Our results show that rainfall-based models in both their deterministic and stochastic formulations outperform models that do not account for rainfall. In fact, classical SIRB models are not able to reproduce the second epidemiological peak, thus suggesting that it was rainfall-driven. Moreover we found stronger support across model types for rainfall acting on increased exposure rather than on exacerbated water contamination. Although these results are context-specific, they stress the importance of a systematic and comprehensive appraisal of transmission pathways and their environmental forcings when embarking in the modelling of epidemic cholera.

PMID: 30465744 [PubMed - indexed for MEDLINE]

Cholera prevention and control in Asian countries.

Cholera prevention and control in Asian countries.

BMC Proc. 2018;12(Suppl 13):62

Authors: Ahmed MU, Baquilod M, Deola C, Tu ND, Anh DD, Grasso C, Gautam A, Hamzah WM, Heng S, Iamsirithaworn S, Kadim M, Kar SK, Le Thi Quynh M, Lopez AL, Lynch J, Memon I, Mengel M, Long VN, Pandey BD, Quadri F, Saadatian-Elahi M, Gupta SS, Sultan A, Sur D, Tan DQ, Ha HTT, Hein NT, Lan PT, Upreti SR, Endtz H, Ganguly NK, Legros D, Picot V, Nair GB

Abstract
Cholera remains a major public health problem in many countries. Poor sanitation and inappropriate clean water supply, insufficient health literacy and community mobilization, absence of national plans and cross-border collaborations are major factors impeding optimal control of cholera in endemic countries. In March 2017, a group of experts from 10 Asian cholera-prone countries that belong to the Initiative against Diarrheal and Enteric Diseases in Africa and Asia (IDEA), together with representatives from the World Health Organization, the US National Institutes of Health, International Vaccine Institute, Agence de médecine préventive, NGOs (Save the Children) and UNICEF, met in Hanoi (Vietnam) to share progress in terms of prevention and control interventions on water, sanitation and hygiene (WASH), surveillance and oral cholera vaccine use. This paper reports on the country situation, gaps identified in terms of cholera prevention and control and strategic interventions to bridge these gaps.

PMID: 30807619 [PubMed]

Estimating cholera incidence with cross-sectional serology.

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Estimating cholera incidence with cross-sectional serology.

Sci Transl Med. 2019 Feb 20;11(480):

Authors: Azman AS, Lessler J, Luquero FJ, Bhuiyan TR, Khan AI, Chowdhury F, Kabir A, Gurwith M, Weil AA, Harris JB, Calderwood SB, Ryan ET, Qadri F, Leung DT

Abstract
The development of new approaches to cholera control relies on an accurate understanding of cholera epidemiology. However, most information on cholera incidence lacks laboratory confirmation and instead relies on surveillance systems reporting medically attended acute watery diarrhea. If recent infections could be identified using serological markers, cross-sectional serosurveys would offer an alternative approach to measuring incidence. Here, we used 1569 serologic samples from a cohort of cholera cases and their uninfected contacts in Bangladesh to train machine learning models to identify recent Vibrio cholerae O1 infections. We found that an individual's antibody profile contains information on the timing of V. cholerae O1 infections in the previous year. Our models using six serological markers accurately identified individuals in the Bangladesh cohort infected within the last year [cross-validated area under the curve (AUC), 93.4%; 95% confidence interval (CI), 92.1 to 94.7%], with a marginal performance decrease using models based on two markers (cross-validated AUC, 91.0%; 95% CI, 89.2 to 92.7%). We validated the performance of the two-marker model on data from a cohort of North American volunteers challenged with V. cholerae O1 (AUC range, 88.4 to 98.4%). In simulated serosurveys, our models accurately estimated annual incidence in both endemic and epidemic settings, even with sample sizes as small as 500 and annual incidence as low as two infections per 1000 individuals. Cross-sectional serosurveys may be a viable approach to estimating cholera incidence.

PMID: 30787170 [PubMed - in process]

Cholera Epidemic in South Sudan and Uganda and Need for International Collaboration in Cholera Control.

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Cholera Epidemic in South Sudan and Uganda and Need for International Collaboration in Cholera Control.

Emerg Infect Dis. 2018 05;24(5):883-887

Authors: Abubakar A, Bwire G, Azman AS, Bouhenia M, Deng LL, Wamala JF, Rumunu J, Kagirita A, Rauzier J, Grout L, Martin S, Orach CG, Luquero FJ, Quilici ML

Abstract
Combining the official cholera line list data and outbreak investigation reports from the ministries of health in Uganda and South Sudan with molecular analysis of Vibrio cholerae strains revealed the interrelatedness of the epidemics in both countries in 2014. These results highlight the need for collaboration to control cross-border outbreaks.

PMID: 29664387 [PubMed - indexed for MEDLINE]

Organization and implementation of an oral cholera vaccination campaign in an endemic urban setting in Dhaka, Bangladesh.

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Organization and implementation of an oral cholera vaccination campaign in an endemic urban setting in Dhaka, Bangladesh.

Glob Health Action. 2019;12(1):1574544

Authors: Khan IA, Khan AI, Rahman A, Siddique SA, Islam MT, Bhuiyan MAI, Chowdhury AI, Saha NC, Biswas PK, Saha A, Chowdhury F, Clemens JD, Qadri F

Abstract
Bangladesh has historically been cholera endemic, with seasonal cholera outbreaks occurring each year. In collaboration with the government of Bangladesh, the Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) initiated operational research to test strategies to reach the high-risk urban population with an affordable oral cholera vaccine (OCV) "ShancholTM" and examine its effectiveness in reducing diarrhea due to cholera. Here we report a sub-analysis focusing on the organization, implementation and effectiveness of different oral cholera vaccine delivery strategies in the endemic urban setting in Bangladesh. We described how the vaccination program was planned, prepared and implemented using different strategies to deliver oral cholera vaccine to a high-risk urban population in Dhaka, Bangladesh based on administrative data and observations made during the program. The objective of this study is to evaluate the organization, implementation and effectiveness of different oral cholera vaccine delivery strategies in the endemic urban setting in Bangladesh. OCV administration by trained local volunteers through outreach sites and mop-up activities yielded high coverage of 82% and 72% of 172,754 targeted individuals for the first and second dose respectively, using national Expanded Program on Immunization (EPI) campaign mechanisms without disrupting routine immunization activities. The cost of delivery was low. Safety and cold chain requirements were adequately managed. The adopted strategies were technically and programmatically feasible. Current evidence on implementation strategies in different settings together with available OCV stockpiles should encourage at-risk countries to use OCV along with other preventive and control measures.

PMID: 30764750 [PubMed - in process]

Characterization of the clonal profile of methicillin resistant Staphylococcus aureus isolated from patients with early post-operative orthopedic implant based infections.

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Characterization of the clonal profile of methicillin resistant Staphylococcus aureus isolated from patients with early post-operative orthopedic implant based infections.

Ann Clin Microbiol Antimicrob. 2019 Feb 13;18(1):8

Authors: Jain S, Chowdhury R, Datta M, Chowdhury G, Mukhopadhyay AK

Abstract
BACKGROUND: To analyze the molecular epidemiology and to compare between the major methicillin resistant Staphylococcus aureus biotypes for association with patient characteristics who had an implant for closed fracture and developed early post-operative wound infections (POWI) in a tertiary care hospital of India.
METHODS: Pulsed-field gel electrophoresis (PFGE), antimicrobial resistance, accessory gene regulator (agr) and staphylococcal cassette chromosome mec (SCCmec) types, Paton-Valentine leukocidin (PVL) gene, toxin gene profiling, biofilm formation and patient demographics were correlated with MLST clonal complexes (CC).
FINDINGS: Overall eight different sequence types (STs) were detected with a predominance of ST239 (66%), ST22 (18%) and some minor types ST772, ST30 (4% each) ST1, ST642, ST6, ST107 (2% each). All ST239 isolates belong to CC239 and SCCmec III whereas ST22 isolates belong to CC22 and SCCmec IV. The isolates varied in the distribution of various toxin genes. With 63.63% biofilm formers ST239 were all multidrug resistant with frequent resistance to erythromycin, clindamycin, gentamicin, cefuroxime, amoxyclav and ciprofloxacin indicating doxycycline, amikacin, vancomycin and linezolid can be the drug of choice.
CONCLUSION: This study shows that ST239 MRSA is still most prevalent strain with new emergence of ST642 and ST107 isolates in association with orthopedic implant based POWI. As compare to other ST types ST239 strain was associated with adverse treatment outcomes. This highlights the importance of improving nosocomial infection control measures in this unit.

PMID: 30760263 [PubMed - in process]

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