Cholera Control Research Articles

The cholera risk assessment in Kano State, Nigeria: A historical review, mapping of hotspots and evaluation of contextual factors.

Nigeria is endemic for cholera since 1970, and Kano State report outbreaks annually with high case fatality ratios ranging from 4.98%/2010 to 5.10%/2018 over the last decade. However, interventions focused on cholera prevention and control have been hampered by a lack of understanding of hotspot Local Government Areas (LGAs) that trigger and sustain yearly outbreaks. The goal of this study was to identify and categorize cholera hotspots in Kano State to inform a national plan for disease control and elimination in the State. We obtained LGA level confirmed and suspected cholera data from 2010 to 2019 from the Nigeria Centre for Disease Control (NCDC) and Kano State Ministry of Health. Data on inland waterbodies and population numbers were obtained from online sources and NCDC, respectively. Clusters (hotspots) were identified using SaTScan through a retrospective analysis of the data for the ten-year period using a Poisson discrete space-time scan statistic. We also used a method newly proposed by the Global Task Force on Cholera Control (GTFCC) to identify and rank hotspots based on two epidemiological indicators including mean annual incidence per 100 000 population of reported cases and the persistence of cholera for the study period. In the ten-year period, 16,461 cholera cases were reported with a case fatality ratio of 3.32% and a mean annual incidence rate of 13.4 cases per 100 000 population. Between 2010 and 2019, the most severe cholera exacerbations occurred in 2014 and 2018 with annual incidence rates of 58.01 and 21.52 cases per 100 000 inhabitants, respectively. Compared to 2017, reported cases and deaths increased by 214.56% and 406.67% in 2018. The geographic distribution of outbreaks revealed considerable spatial heterogeneity with the widest in 2014. Space-time clustering analysis identified 18 out of 44 LGAs as high risk for cholera (hotspots) involving both urban and rural LGAs. Cholera clustered around water bodies, and the relative risk of having cholera inside the hotspot LGA were 1.02 to 3.30 times higher than elsewhere in the State. A total of 4,894,144 inhabitants were in these hotspots LGAs. Of these, six LGAs with a total population of 1.665 million had a relative risk greater than 2 compared to the state as a whole. The SaTScan (statistical) and GTFCC methods were in agreement in hotspots identification. This study identified cholera hotspots LGAs in Kano State from 2010–2019. Hotspots appeared in both urban and rural settings. Focusing control strategies on these hotspots will facilitate control and eliminate cholera from the State.

Cholera risk in cities in Uganda: understanding cases and contacts centered strategy (3CS) for rapid cholera outbreak control.

Introductionin the recent past, cities in sub-Saharan Africa have reported serious cholera outbreaks that last for several months. Uganda is one of the African countries where cities are prone to cholera outbreaks. Studies on cholera in Bangladesh show increased risk of cholera for the immediate household members (contacts) yet the control interventions mainly target cases with little or no focus on contacts. This study aimed to describe the rapid control of cholera outbreaks in Kampala and Mbale cities, Uganda, using, “Cases and Contacts Centered Strategy (3CS)” that consisted of identification and treatment of cases, promotion of safe water, sanitation, hygiene (WaSH) and selective chemoprophylaxis for the contacts.Methodsa cross-sectional study was conducted in 2015-2016 in the Kampala and Mbale cities during cholera outbreaks. Cholera cases were treated and 816 contacts from 188 households were listed and given cholera preventive packages. Data were collected, cleaned, analysed and stored in spreadsheet. Comparison of categories was done using Chi-Square test.Resultsa total of 58 and 41 confirmed cholera cases out of 318 and 153 suspected cases were recorded in Kampala and Mbale cities respectively. The outbreaks lasted for 41 days in both cities. Case fatality rates were high; 12.1% (5/41) for Mbale city and 1.7% (1/58) for Kampala city. Fifty-five percent (210/379) of stool samples were tested by culture to confirm V. choleraeO1. No contacts listed and given cholera preventive package developed cholera. Both sexes and all age groups were affected. In Kampala city, the males were more affected than the females in the age groups less than 14 years, p-value of 0.0097.Conclusionthis study showed that by implementing 3CS, it was possible to rapidly control cholera outbreaks in Kampala and Mbale cities and no cholera cases were reported amongst the listed household contacts. The findings on 3CS and specifically, selective antibiotic chemoprophylaxis for cholera prevention, could be used in similar manner to oral cholera vaccines to complement the core cholera control interventions (disease surveillance, treatment of cases and WaSH). However, studies are needed to guide such rollout and to understand the age-sex differences in Kampala city.

Cholera pulse vaccination: A possible elimination strategy for cholera in endemic countries.

Cholera is a diarrheal disease causing major health issue in developing countries where it is endemic and causes outbreaks. India ranks first with an estimated 675,188 number of cases and 20,256 number of deaths annually with one-third of its population at risk. The two broad approaches for cholera control are improving sanitation and vaccination. Now both live and killed oral vaccines are available. Live vaccines are advantageous in respect of intestinal colonization and rapid immune response and also lead to in vivo exposure of bacterial products leading to good immunological response against wild Vibrio cholerae infection. The three major delivery strategies which can be considered for the implementation of oral cholera vaccine are preemptive vaccination, reactive vaccinations, and National Immunization Program. We propose the use of cholera live oral vaccines for achieving control of this disease by repeated vaccination of the susceptible population in a series of pulses to control it from the entire population.

Profile of Suspected Cholera Patients during May – November 2017 in Sanaa City Secondary Analysis

Introduction: From 27 April to 3 August 2017, 453,175 suspected cholera cases and 1,930 deaths (CFR: 0.4%) have been reported in 95.6% (22/23) of Yemen governorates, and 89.2% (297/333) of the districts.
 The five most affected governorates were Amanat Al-Asima, Al Hudaydah, Hajjah, Amran and Dhamar with 53% (239,877/453,175) of the cases reported since 27 April 2017. In amanat al Asimah (Sana'a city) 55563 cases 61 deaths are registered in that period with case fatality rate 0.1% and attack rate 1.68%
 Objectives: To study Profile of suspected cholera patients in Sanaa city.
 Materials and Methods: A retrospective descriptive study was carried out by using secondary analysis of available data collected from (DTCs), (ORCs) and other health facilities by department of epidemiological surveillance – Sanaa city health office.
 Results: A total of 92995 suspected cholera patients were included in the study whereas the average age of study subjects was 22.7 years where standard deviation (SD) 18.8 most affected age groups were (15-29),(5-14),(<5) the predominant of the study subjects from Sanaa city (96%) from Ma'ain, Bani-Alhareth, AND Al-Sabain districts Most cases are reported from DTCs (59300), ORCs (29547) Cases starts to appear in week 17 reaches a peak in weeks 24,25 and then slowly decreases. 155 suspected cholera cases were culture positives
 Conclusion: 1. Cholera is one of the urgent health problems in Sana’a city
 
 Cholera distribution is not gender sensitive, the most affected age group is (15-29) years, followed by (5-14) then under five
 Cases are mainly distributed in Ma'ain, Bani-Alhareth, & Al-Sabain within Sana’a city (50% of the total cases).
 The main cholera health care facilities are mainly DTCs and ORCs supported by WHO & UNICEF
 Most of the subjects seek medical care within the first 2 days after onset of symptoms
 The peak of cholera suspected cases is registered in weeks 24 & 24.
 Confirmed cholera cases by culture are 155 from 655 specimen tested whereas 1984 are positive by cholera RDT
 
 Recommendations:1. More cholera control interventions are necessary and urgent to eradicate it.
 
 More field related research must be carried out to guide control and management interventions.
 Some interventions must be concentrated on the age groups 5-14 & under five and at the most affected areas.

Use of surveys to evaluate an integrated oral cholera vaccine campaign in response to a cholera outbreak in Hoima district, Uganda

ObjectivesTo evaluate the quality and coverage of the campaign to distribute oral cholera vaccine (OCV) during a cholera outbreak in Hoima, Uganda to guide future campaigns of cholera vaccine.DesignSurvey of...

Challenges and opportunities of setting-up a Cholera surveillance Microbiology laboratory in a research-naïve rural setting in Mozambique

Background: Limited microbiology capacity, important to confirm clinical diagnosis, impacts diagnostic and treatment of infectious diseases such as Cholera in LMICs. In Mozambique, is only possible in tertiary care, each serving ∼6million habitants and we implemented it in a secondary-care rural hospital, supported by Cholera Prevention and Control Project (MOCA) in partnership with the National Institute of Health (INS) and the International Vaccine Institute (IVI); Developed integrated approach comprising surveillance, vaccination campaign and WaSH, in a Cholera endemic District with challenging precarious roads and no microbiological diagnostic. Methods and materials: Key elements for the lab implementation included: engagement of international partners (IVI and KOICA) in providing a low-cost infrastructure (20”container), basic equipment and reagents; local partners (INS and MoH) engagement with local authorities in providing human resources and training both at central level and also local on-going training during project's supervision visits (every 2 months). Training package including translation of resource-rich practices to a resource-limited setting, such as using manual, instead of maintenance-intensive automated machinery, translation of standards procedures to support all levels of staff and the implementation of a stepwise quality assurance programme. Results: This lab will support MOCA's surveillance, implemented in 6 health care facilities (HCF), and the remainder districts health care network (16HCF), serving a population of 264,788 habitants. Capacity has been created for microbiological diagnostics other than diarrheal diseases and the newly implemented capacity will help focus interventions, identify and monitor outbreaks, and provide information for reports on newly emerging serotypes and changes in antibiotic resistance. Conclusion: The global roadmap to end cholera transmission by 90% in 2030 advocates for “a strategy focusing on containing outbreaks through early detection and rapid response. Through strengthening early warning surveillance and laboratory capacities, to drastically reduce the number of deaths from cholera.” Development of low- and middle-income country models of services, like this, are important to address antimicrobial resistance, burden of underreported pathogens and improve diagnosis and patient treatment and will be readily incorporated into routine clinical practice. Political commitment is crucial for the sustainability of the service and further studies should observe the impact in diagnosis and treatment of patients due to laboratory diagnosis.

Vibrio cholerae O1 transmission in Bangladesh: insights from a nationally representative serosurvey

SummaryBackgroundPandemic Vibrio cholerae from cholera-endemic countries around the Bay of Bengal regularly seed epidemics globally. Without reducing cholera in these countries, including Bangladesh, global cholera control might never be achieved. Little is known about the geographical distribution and magnitude of V cholerae O1 transmission nationally. We aimed to describe infection risk across Bangladesh, making use of advances in cholera seroepidemiology, therefore overcoming many of the limitations of current clinic-based surveillance.MethodsWe tested serum samples from a nationally representative serosurvey in Bangladesh with eight V cholerae-specific assays. Using these data with a machine-learning model previously validated within a cohort of confirmed cholera cases and their household contacts, we estimated the proportion of the population with evidence of infection by V cholerae O1 in the previous year (annual seroincidence) and used Bayesian geostatistical models to create high-resolution national maps of infection risk.FindingsBetween Oct 16, 2015, and Jan 24, 2016, we obtained and tested serum samples from 2930 participants (707 households) in 70 communities across Bangladesh. We estimated national annual seroincidence of V cholerae O1 infection of 17·3% (95% CI 10·5–24·1). Our high-resolution maps showed large heterogeneity of infection risk, with community-level annual infection risk within the sampled population ranging from 4·3% to 62·9%. Across Bangladesh, we estimated that 28·1 (95% CI 17·1–39·2) million infections occurred in the year before the survey. Despite having an annual seroincidence of V cholerae O1 infection lower than much of Bangladesh, Dhaka (the capital of Bangladesh and largest city in the country) had 2·0 (95% CI 0·6–3·9) million infections during the same year, primarily because of its large population.InterpretationSerosurveillance provides an avenue for identifying areas with high V cholerae O1 transmission and investigating key risk factors for infection across geographical scales. Serosurveillance could serve as an important method for countries to plan and monitor progress towards 2030 cholera elimination goals.FundingThe Bill & Melinda Gates Foundation, National Institutes of Health, and US Centers for Disease Control and Prevention.

Endemic Cholera in India and Imported Cholera in Russia: What is Common?

The endemicity of cholera in India has been well researched. Among the other endemic areas, Indian subcontinent appears to be the cradle of Vibrio cholerae genovariants, which subsequently spread worldwide. In contrast, all the cholera cases recorded in Russia are of imported origin. In the past century, such importations might result in epidemics, which, however, ended with elimination of toxigenic V. cholerae (TVC) from the affected areas. Currently, the incidence of TVC in water reservoirs or infected returnees from Asian countries are rare events, mostly due to constant surveillance activities. Furthermore, the climatic conditions in the majority of Russian regions are unfavorable for longterm environmental survival of the pathogen. On the other hand, global shifts in climate accompanied by unexpected anomalies in previously stable climatic zones may promote dissemination of imported TVC and emergence of cholera. In some regions of Russia, seasonal weather patterns are pretty similar to Indian. Molecular studies of isolates from diverse territories show that TVC have been introduced into new areas and acquired additional traits, absent in their ancestors.This article describes genomic characteristics of TVC isolates from Russia, India and some other countries. The review is complemented by bioinformatics analysis of important genetic markers to discriminate between clones that emerged in endemic regions and were imported into cholera-free locations. We have found more evidence in support of primary Indian origin of recent genovariants and their ongoing transformation, including the emergence of a new rtxA gene allele with a 60 bp deletion in addition to the previously known null mutation. In certain conditions, TVC could pose a potential threat of spreading epidemic cholera into Russia and other territories. Cholera control requires joint efforts of researchers to learn more about the pathogen at the molecular level for developing effective strategies to protect the humankind throughout the world.

Cholera knowledge, socioeconomic and WaSH characteristics in Aden - Yemen, 2017: a community-based comparative survey.

SummaryObjectivesTo improve prevention and control response to the cholera outbreak, we sought to assess and compare the community’s cholera awareness and needs in high and low epidemic areas in Aden.MethodsA community-based comparative survey was conducted in 2017. We used multi-stage cluster sampling. Eligible household heads in high and low epidemic areas were interviewed. The data collected from both areas using a pretested questionnaire.ResultsCholera cases and mortality were higher in high epidemic areas compared with low epidemic areas. Socioeconomic, water, sanitation, and hygienic conditions were poorer in high epidemic areas compared with low epidemic areas. Knowledge of cholera transmission and prevention was sub-optimal in both areas. We found a mismatch between the delivered education and distributed preventive materials.ConclusionsStakeholders should tailor the design, content, and implementation of future cholera prevention and control methods to meet the needs of the community. Future educational camping should focus on the transmission prevention, including vaccination. Education and sustainable interventions should be implemented to improve the water, sanitation, and hygiene.

An Accidental Nutritionist.

My career as an accidental nutritionist began with my immersion in cholera control, a cyclone disaster, a smallpox epidemic, and formal training in ophthalmology and epidemiology. Interest in blindness prevention inexplicably led me to (re)pioneer the effects, treatment, and prevention of vitamin A deficiency, while faced with intense criticism by many leading scientists in the nutrition community. The resulting efforts by the World Health Organization and UNICEF in support of programs for the global control of vitamin A deficiency still face vocal opposition by some senior scientists, despite having been estimated to have saved tens of millions of children from unnecessary death and blindness. This entire journey was largely an accident!

Antibiotic Susceptibility Testing (AST) Reports: A Basis for Environmental/Epidemiological Surveillance and Infection Control Amongst Environmental Vibrio cholerae.

Distribution, investigation, surveillance and control (DISC) of cholera outbreaks in endemic/non-endemic regions has been a concerted approach towards the management of the causal pathogen. Relevant organization, government, health systems and the public have implemented several steps towards controlling the menace, yet pathogen continues to occur with diverse phenotypes/genotypes of high clinical and epidemiological relevance. The study determines antibiotic susceptibility/resistance pattern of Vibrio cholerae isolates retrieved from six domestic water sources between March and August 2018. Serological and molecular typing methods (polymerase chain reaction or PCR) were used to confirm the isolates identity. Antibiotic susceptibility testing was conducted using six commonly employed antibiotics of V. cholerae according to the recommendation of Clinical Laboratory Standard and European Committee for Antimicrobial Susceptibility Testing with other relevant antibiotics of investigative epidemiology and infection control, employing both disc diffusion test and PCR gene detection. Samples presumptive counts ranged between 1.10 to 7.91 log10 CFU/mL. Amongst the 759 presumptive isolates retrieved, sixty-one were confirmed as V. cholerae which were further serogrouped as Non-O1/Non-O139 V. cholerae. Various V. cholerae resistant phenotypes/genoytypes were detected vis: carbapenemase (CR-Vc; 31.1%/5.3%). New Delhi Metallobetalactamase (NDM-1-Vc; 23.0%/42.5%), extended spectrum betalactamase (ESBL-Vc; 42.6%/blaTEM:86,7%), chloramphenicol resistance (62.3%/Flor: 46.2%}, tetracycline resistance (70.5%/46.7%), AmpC resistance (21.0 (34.4%/56.7%)) and various other resistant genotypes/phenotypes. It was observed that more than 50% of the confirmed V. cholerae isolates possess resistance to two or more antibiotic classes/groups with multiple antibiotic resistance index (MARI) ranging from 0.031 to 0.5. This observation provides necessary information and updates for surveillance, planning and implementation of control strategies for cholera. It would also encourage decision making, formulation of policy by the government and cholera control authorities.

Distribution of hygiene kits during a cholera outbreak in Kasa\xef-Oriental, Democratic Republic of Congo: a process evaluation

BackgroundCholera remains a leading cause of infectious disease outbreaks globally, and a major public health threat in complex emergencies. Hygiene kits distributed to cholera case-households have previously shown an effect in reducing cholera incidence and are recommended by Médecins Sans Frontières (MSF) for distribution to admitted patients and accompanying household members upon admission to health care facilities (HCFs).MethodsThis process evaluation documented the implementation, participant response and context of hygiene kit distribution by MSF during a 2018 cholera outbreak in Kasaï-Oriental, Democratic Republic of Congo (DRC). The study population comprised key informant interviews with seven MSF staff, 17 staff from other organisations and a random sample of 27 hygiene kit recipients. Structured observations were conducted of hygiene kit demonstrations and health promotion, and programme reports were analysed to triangulate data.Results and conclusionsBetween Week (W) 28–48 of the 2018 cholera outbreak in Kasaï-Oriental, there were 667 suspected cholera cases with a 5% case fatality rate (CFR). Across seven HCFs supported by MSF, 196 patients were admitted with suspected cholera between W43-W47 and hygiene kit were provided to patients upon admission and health promotion at the HCF was conducted to accompanying household contacts 5–6 times per day. Distribution of hygiene kits was limited and only 52% of admitted suspected cholera cases received a hygiene kit. The delay of the overall response, delayed supply and insufficient quantities of hygiene kits available limited the coverage and utility of the hygiene kits, and may have diminished the effectiveness of the intervention. The integration of a WASH intervention for cholera control at the point of patient admission is a growing trend and promising intervention for case-targeted cholera responses. However, the barriers identified in this study warrant consideration in subsequent cholera responses and further research is required to identify ways to improve implementation and delivery of this intervention.

Factors responsible for the 2015 Cholera outbreak and spread in Ebonyi state, Nigeria

Background: Cholera outbreaks are frequent across Nigeria irrespective of season. Cholera outbreak began on the 17th January 2015 in a community in Ebonyi State. We carried out an investigation to confirm the diagnosis, identify the source of infection, determine the factors associated with its spread and carried out some interventions.Methods: Descriptive cross-sectional study was carried out in the affected communities during which active case search, environmental survey and key informant interviews were done. Stool samples were taken from cases for laboratory diagnosis. A cholera case was defined as any person that presented with diarrhoea and or vomiting with laboratory confirmation or with epidemiological linkage to the affected areas.Results: A total of 551 cases were recorded in 38 communities with a case fatality rate of 8.6%. Vibrio Cholera was isolated from 5 stool samples. Those who were 20 years or less and females were more commonly affected. Males and attendance at burial in another community within the two weeks preceding onset of outbreak was significantly associated with death (p<0.001). Inadequate safe water supplies, poor sanitation and hygiene practices were observed.Conclusion: The outbreak was caused by Vibrio Cholera. Socio-cultural practices surrounding burial such as overcrowding, ceremonial killing of animals and communal eating together may have contributed to its widespread. A system thinking approach such as behavior change communication and community dialogue are needed for Cholera control.

Three Consecutive Waves of Cholera Outbreak in Ethiopia (2015- 2017): Explanatory Analysis

BACKGROUND: Cholera is an acute epidemic infectious disease. It is characterized by watery diarrhea, extreme loss of fluid and electrolytes, and severe dehydration. Ethiopia faced three consecutive waves of cholera outbreaks: nearly all regional states and city administrations, with the exception of one, were affected. The study was conducted with the aim of describing the epidemiology of the outbreak within the defined three years.METHODS: Secondary data review was conducted along with explanatory methods of analysis individual patient data reported from different corners of the country in the time period of 2015 –2017. Cases were identified using the case definition stated on the national guideline for cholera control in Ethiopia.RESULT: A total of 36,154 cholera cases and 246 deaths were reported (overall case-fatality rate [CFR=0.7%] affecting all regions of the country except Gambella). The outbreak began in 2015 with 238 cases and 2 deaths [CFR=0.8%]. The largest outbreak during the period under this study occurred in 2016, with 29,338 cases and 188 deaths [CFR=0. 6%]. Following a decline in disease occurrence, the country experienced a resurgence of epidemic cholera during 2017 (6,578 cases and 56 deaths; CFR, 0.9%), which declined rapidly to a few cases. AR was higher in males [37.01/100,000] and persons in the age group of 15–44years [44.10/100,000] in 2016.CONCLUSION: The outbreak affected nearly every corner of the country. Taken together, the epidemiological trends of cholera in Ethiopia showed an annual decrement in frequency and length of outbreaks during the 3 years under review. The recent decreases in cholera case counts may reflect cholera control measures put in place by public health authorities of the national Ministry of Health.

Costing oral cholera vaccine delivery using a generic oral cholera vaccine delivery planning and costing tool (CholTool)

ABSTRACT Cholera is both an endemic and epidemic disease in many low and middle-income countries (LMICs). Strategies for cholera control include improving water, sanitation, and hygiene; providing early and effective treatment; and deploying oral cholera vaccine (OCV). This last strategy is relatively new, and countries considering its introduction are interested in knowing the potential cost not only of the vaccine, but also the cost of introduction. This paper describes the costing of OCV introduction in LMICs using a publicly available Excel-based tool known as the CholTool. It includes estimates of delivery cost categories which cover not only the service delivery costs (e.g. vaccine procurement, handling, storage, and transport; vaccination administration, monitoring supervision, and field support), but also the programmatic costs associated with introducing a new vaccine (i.e. microplanning, communication and training materials development, sensitization/social mobilization, and personnel training) to ensure that a comprehensive estimate is provided with health payer perspective. CholTool takes the user through a structured sequence of interlinked modules containing input parameter cells (assumptions), decision cells (variable selections), and formulas (calculations) to produce customized cost estimates based on standardized methods. The tool provides both financial and economic cost estimates, to ensure that both costs are available for consideration. Four examples of applications of CholTool are presented in three countries- one in Ethiopia, two in Malawi and one in Nepal. The estimates of economic delivery cost per dose (including service delivery and programmatic costs) were (in USD 2016): $2.89 in Ethiopia, $3.04 in Malawi1, $3.35 in Malawi2 and $3.06 in Nepal. A cost projection conducted before the campaign using the tool and a retrospective costing using the tool in Nepal resulted in no significant difference between economic delivery costs per dose.

Reproductive, maternal, newborn and child health service delivery during conflict in Yemen: a case study

BackgroundArmed conflict, food insecurity, epidemic cholera, economic decline and deterioration of essential public services present overwhelming challenges to population health and well-being in Yemen. Although the majority of the population is in need of humanitarian assistance and civil servants in many areas have not received salaries since 2016, many healthcare providers continue to work, and families continue to need and seek care.MethodsThis case study examines how reproductive, maternal, newborn, child and adolescent health and nutrition (RMNCAH+N) services have been delivered since 2015, and identifies factors influencing implementation of these services in three governorates of Yemen. Content analysis methods were used to analyze publicly available documents and datasets published since 2000 as well as 94 semi-structured individual and group interviews conducted with government officials, humanitarian agency staff and facility-based healthcare providers and six focus group discussions conducted with community health midwives and volunteers in September–October 2018.ResultsHumanitarian response efforts focus on maintaining basic services at functioning facilities, and deploying mobile clinics, outreach teams and community health volunteer networks to address urgent needs where access is possible. Attention to specific aspects of RMNCAH+N varies slightly by location, with differences driven by priorities of government authorities, levels of violence, humanitarian access and availability of qualified human resources. Health services for women and children are generally considered to be a priority; however, cholera control and treatment of acute malnutrition are given precedence over other services along the continuum of care. Although health workers display notable resilience working in difficult conditions, challenges resulting from insecurity, limited functionality of health facilities, and challenges in importation and distribution of supplies limit the availability and quality of services.ConclusionsChallenges to providing quality RMNCAH+N services in Yemen are formidable, given the nature and scale of humanitarian needs, lack of access due to insecurity, politicization of aid, weak health system capacity, costs of care seeking, and an ongoing cholera epidemic. Greater attention to availability, quality and coordination of RMNCAH services, coupled with investments in health workforce development and supply management are needed to maintain access to life-saving services and mitigate longer term impacts on maternal and child health and development. Lessons learned from Yemen on how to address ongoing primary health care needs during massive epidemics in conflict settings, particularly for women and children, will be important to support other countries faced with similar crises in the future.

Stemming cholera tides in Zimbabwe through mass vaccination

BackgroundIn 2018, Zimbabwe declared another major cholera outbreak a decade after recording one of the worst cholera outbreaks in Africa. MethodsA mathematical model for cholera was used to estimate the magnitude of the cholera outbreak and vaccination coverage using cholera cases reported data. A Markov chain Monte Carlo method based on a Bayesian framework was used to fit the model in order to estimate the basic reproductive number and required vaccination coverage for cholera control. ResultsThe results showed that the outbreak had a basic reproductive number of 1.82 (95% credible interval [CrI] 1.53–2.11) and required vaccination coverage of at least 58% (95% Crl 45–68%) to be contained using an oral cholera vaccine of 78% efficacy. Sensitivity analysis demonstrated that a vaccine with at least 55% efficacy was sufficient to contain the outbreak but at higher coverage of 75% (95% Crl 58–88%). However, high-efficacy vaccines would greatly reduce the required coverage, with 100% efficacy vaccine reducing coverage to 45% (95% Crl 35–53%). ConclusionsThese findings reinforce the crucial need for oral cholera vaccines to control cholera in Zimbabwe, considering that the decay of water reticulation and sewerage infrastructure is unlikely to be effectively addressed in the coming years.

A mathematical model of cholera in a periodic environment with control actions

In this paper, we studied the impact of sensitization and sanitation as possible control actions to curtail the spread of cholera epidemic within a human community. Firstly, we combined a model of Vibrio Cholerae with a generic SIRS cholera model. Classical control strategies in terms of the sensitization of population and sanitation are integrated through the impulsive differential equations. Then we presented the theoretical analysis of the model. More precisely, we computed the disease free equilibrium. We derive the basic reproduction number [Formula: see text] which determines the extinction and the persistence of the infection. We show that the trivial disease-free equilibrium is globally asymptotically stable whenever [Formula: see text], while when [Formula: see text], the trivial disease-free equilibrium is unstable and there exists a unique endemic equilibrium point which is globally asymptotically stable. Theoretical results are supported by numerical simulations, which further suggest that the control of cholera should consider both sensitization and sanitation, with a strong focus on the latter.

What are the drivers of recurrent cholera transmission in Nigeria? Evidence from a scoping review

BackgroundThe 2018 cholera outbreak in Nigeria affected over half of the states in the country, and was characterised by high attack and case fatality rates. The country continues to record cholera cases and related deaths to date. However, there is a dearth of evidence on context-specific drivers and their operational mechanisms in mediating recurrent cholera transmission in Nigeria. This study therefore aimed to fill this important research gap, with a view to informing the design and implementation of appropriate preventive and control measures.MethodsFour bibliographic literature sources (CINAHL (Plus with full text), Web of Science, Google Scholar and PubMed), and one journal (African Journals Online) were searched to retrieve documents relating to cholera transmission in Nigeria. Titles and abstracts of the identified documents were screened according to a predefined study protocol. Data extraction and bibliometric analysis of all eligible documents were conducted, which was followed by thematic and systematic analyses.ResultsForty-five documents met the inclusion criteria and were included in the final analysis. The majority of the documents were peer-reviewed journal articles (89%) and conducted predominantly in the context of cholera epidemics (64%). The narrative analysis indicates that social, biological, environmental and climatic, health systems, and a combination of two or more factors appear to drive cholera transmission in Nigeria. Regarding operational dynamics, a substantial number of the identified drivers appear to be functionally interdependent of each other.ConclusionThe drivers of recurring cholera transmission in Nigeria are diverse but functionally interdependent; thus, underlining the importance of adopting a multi-sectoral approach for cholera prevention and control.

Toxigenic Vibrio cholerae evolution and establishment of reservoirs in aquatic ecosystems

The spread of cholera in the midst of an epidemic is largely driven by direct transmission from person to person, although it is well-recognized that Vibrio cholerae is also capable of growth and long-term survival in aquatic ecosystems. While prior studies have shown that aquatic reservoirs are important in the persistence of the disease on the Indian subcontinent, an epidemiological view postulating that locally evolving environmental V. cholerae contributes to outbreaks outside Asia remains debated. The single-source introduction of toxigenic V. cholerae O1 in Haiti, one of the largest outbreaks occurring this century, with 812,586 suspected cases and 9,606 deaths reported through July 2018, provided a unique opportunity to evaluate the role of aquatic reservoirs and assess bacterial transmission dynamics across environmental boundaries. To this end, we investigated the phylogeography of both clinical and aquatic toxigenic V. cholerae O1 isolates and show robust evidence of the establishment of aquatic reservoirs as well as ongoing evolution of V. cholerae isolates from aquatic sites. Novel environmental lineages emerged from sequential population bottlenecks, carrying mutations potentially involved in adaptation to the aquatic ecosystem. Based on such empirical data, we developed a mixed-transmission dynamic model of V. cholerae, where aquatic reservoirs actively contribute to genetic diversification and epidemic emergence, which underscores the complexity of transmission pathways in epidemics and endemic settings and the need for long-term investments in cholera control at both human and environmental levels.