Cholera Control Research Articles

Renewed Interest in Cholera Control

Cholera is an ancient disease of significant public health importance accounting for approximately 1.3-4 million cases worldwide and about 21000–143,000 deaths. Cholera is endemic in many developing countries where sanitation is poor and lack in safe water. The disease has the potential to cause large-scale epidemics and pandemics. The ongoing seventh pandemic has spread to more than 100 countries since its origin in 1961 in Indonesia. Travellers from developed countries travelling to cholera endemic areas are at higher risk of getting cholera. Oral rehydration therapy (ORT) has revolutionized the treatment of cholera and causes reduction of mortality. ORT has saved the lives of millions of children all over the world and is considered the single most significant discovery in medicine of the century. Effective oral cholera vaccines have been developed and are being used but not to its full potential to control cholera. Since the disease burden due to cholera is huge and we have the tools to combat cholera, particularly reduce mortality, it is imperative that the global communities should embark on cholera control as an urgent priority of human health. Cholera control should be viewed as a poverty alleviation programme for the marginalised population. The current pandemic of COVID-19 overwhelmed the economy and healthcare systems so much so that the health authorities undermined the cholera control measures even during ongoing epidemics of cholera. The World Health Organization (WHO) has reframed the strategy with renewed interest on cholera control with a target of reducing the mortality from cholera by 90 percent by 2030. Member countries should mobilize enough funds for the programme and actively implement it. Improvement of sanitation and safe water for all should continue as long-term solution for combating the menace of cholera.

Diagnosis, Management, and Future Control of Cholera.

Cholera, caused by Vibrio cholerae, persists in developing countries due to inadequate access to safe water, sanitation, and hygiene. There are approximately 4 million cases and 143,000 deaths each year due to cholera. The disease is transmitted fecally-orally via contaminated food or water. Severe dehydrating cholera can progress to hypovolemic shock due to the rapid loss of fluids and electrolytes, which requires a rapid infusion of intravenous (i.v.) fluids. The case fatality rate exceeds 50% without proper clinical management but can be less than 1% with prompt rehydration and antibiotics. Oral cholera vaccines (OCVs) serve as a major component of an integrated control package during outbreaks or within zones of endemicity. Water, sanitation, and hygiene (WaSH); health education; and prophylactic antibiotic treatment are additional components of the prevention and control of cholera. The World Health Organization (WHO) and the Global Task Force for Cholera Control (GTFCC) have set an ambitious goal of eliminating cholera by 2030 in high-risk areas.

Economic impact of cholera in households in rural southern Malawi: a prospective study

IntroductionCholera remains a significant contributor to diarrhoeal illness, especially in sub-Saharan Africa. Few studies have estimated the cost of illness (COI) of cholera in Malawi, a cholera-endemic country. The present...

Cholera: A Recent Epidemic

Cholera in an intestinal infection caused by Vibrio cholerae. Its symptoms include profuse secretory diarrhea. Cholera can be endemic, epidemic or pandemic. This disease still remains a challenge to the modern world. Although it can be asymptomatic or mild but in severe complications it can cause death within hours due to dehydration. About one in 20 infected people have severe water diarrhea along with vomiting, leading to dehydration. Even the asymptomatic people can spread the infection. Other symptoms include rapid heart rate, loss of skin elasticity, dry mucous membranes, low blood pressure, thirst and muscle cramps.
 Precautionary measures include increased water intake and use of boiled water for drinking, washing face, teeth, washing vegetable and fruits, washing utensils. Avoid raw or unpeeled fruits and vegetables, unpasteurized milk, uncooked meat. It is highly treatable disease but hydration is must and maintained. Antibiotics are not used for emergency treatment but it can only reduce the span of disease by half and thus help in further spread of disease [1].
 Director General of ‘Global Task Force; on cholera control side event in observance of WHA, held of 25th May, 2022 stated that, ‘Although cholera was eliminated from the globe north more than 150 years ago, it continues to plague the global south. Cholera is a disease of inequity. Almost exclusively, it affects the communities without adequate water, sanitation and hygiene and those who have been displaced. Despite pandemic, humanitarian crises and natural disasters, the Democratic Republic of Congo, Malawi, Tanzania, Uganda, Yemen, Zambia all conducted preventive campaigns with oral cholera vaccine. Cases and deaths have declined in the recent years but preliminary data for 2021 shows a massive increase in the number of cholera-related death, with an average case fatality rate of 3%. The trend in 2022 remains very concerning, with at least 14 countries experiencing new cholera outbreaks. This is why the work of Global Task Force on Cholera Control is so important’ [2].

Infectious Disease Control and Management in Ethiopia: A Case Study of Cholera.

Cholera remains a significant public health problem among the vulnerable populations living in many resource-limited settings with poor access to safe and clean water and hygiene practice. Around 2.86 million cholera cases and 95,000 deaths are estimated to occur in endemic countries. In Ethiopia, cholera has been one of the major epidemic diseases since 1634 when the first cholera outbreak was recorded in-country. Several cholera epidemics occurred with recent outbreaks in 2019–2021. Cholera has been often reported as acute watery diarrhea due to limited diagnostic capacity in remote areas in Ethiopia and sensitivities around cholera outbreaks. The government of Ethiopia has been executing several phases of multi-year health sector development plan in the past decades and has recently developed a national cholera control plan. Here, we aim to present the existing cholera control guidelines and health system in Ethiopia, including case detection and reporting, outbreak declaration, case management, and transmission control. Challenges and way forward on further research and public health interventions are also discussed to address the knowledge and health service gaps related to cholera control in Ethiopia.

Application of the Child Health and Nutrition Research Initiative (CHNRI) methodology to prioritize research to enable the implementation of Ending Cholera: A global roadmap to 2030.

The "Ending Cholera: A Global Roadmap to 2030" (Roadmap) was launched in October 2017. Following its launch, it became clear that additional evidence is needed to assist countries in controlling cholera and that a prioritized list of research questions is required to focus the limited resources to address the issues most relevant to the implementation of the Roadmap. A comprehensive list of research questions was developed based on inputs from the Working Groups of the Global Taskforce for Cholera Control and other experts. The Child Health and Nutrition Research Initiative methodology was adapted to identify the relevant assessment criteria and assign weights to each criterion. The assessment criteria were applied to each research question by cholera experts to derive a score based on which they were prioritized. The consultation process involved 177 experts and stakeholders representing different constituencies and geographies with research priority scores ranging from 88·8 to 65·7% and resulted in the prioritization of the top 20 research questions across all Roadmap pillars, the top five research questions for each Roadmap pillar, and three discovery research questions. This resulted in 32 non-duplicative research questions that considers both immediate and long-term Roadmap goals. The transparent, inclusive, and rigorous process to develop a Research Agenda is aimed to secure broad buy-in and serve as a guide for funding agencies and researchers to focus their efforts to fill the evidence gaps plaguing cholera-endemic countries.

Cholera outbreaks in sub-Saharan Africa during 2010-2019: a descriptive analysis

BackgroundCholera remains a public health threat but is inequitably distributed across sub-Saharan Africa. Lack of standardized reporting and inconsistent outbreak definitions limit our understanding of cholera outbreak epidemiology. MethodsFrom a database of cholera incidence and mortality, we extracted data from sub-Saharan Africa and reconstructed outbreaks of suspected cholera starting in January 2010 to December 2019 based on location-specific average weekly incidence rate thresholds. We then described the distribution of key outbreak metrics. ResultsWe identified 999 suspected cholera outbreaks in 744 regions across 25 sub-Saharan African countries. The outbreak periods accounted for 1.8 billion person-months (2% of the total during this period) from January 2010 to January 2020. Among 692 outbreaks reported from second-level administrative units (e.g., districts), the median attack rate was 0.8 per 1000 people (interquartile range (IQR), 0.3-2.4 per 1000), the median epidemic duration was 13 weeks (IQR, 8-19), and the median early outbreak reproductive number was 1.8 (range, 1.1-3.5). Larger attack rates were associated with longer times to outbreak peak, longer epidemic durations, and lower case fatality risks. ConclusionsThis study provides a baseline from which the progress toward cholera control and essential statistics to inform outbreak management in sub-Saharan Africa can be monitored.

Etiological and epidemiological characteristics of Vibrio cholerae in Beijing, 2015-2021

Objective: To analyze the etiological and epidemiological characteristics of Vibrio cholerae in Beijing during 2015-2021 and provide evidence for the prevention and control of cholera. Methods: The V. cholerae strains isolated in Beijing during 2015-2021 were analyzed by serotyping and virulence genes detection. Pulsed field gel electrophoresis (PFGE) was performed for the molecular typing of the strains. Based on the collected epidemiological and clinical data of cholera cases,the epidemiological characteristics of cholera were analyzed by descriptive epidemiology method. Results: A total of 76 Vibrio cholerae O1 strains were isolated in Beijing during 2015-2021, including 61 strains from human, 10 strains from environment and 5 strains from seafood. The 76 strains consisted of 68 Ogawa strains and 8 Inaba strains. Six Ogawa strains isolated from sporadic cases carried ctxAB. After NotⅠ digestion, 76 strains were divided into 33 PFGE patterns. From 2015 to 2021, a total of 38 cholera epidemics were reported in Beijing, most of them were sporadic ones, accounting for 92.11% (35/38). A total of 45 cases were reported, and the cases occurred during June-September accounted for 97.78% (44/45). Cholera cases occurred in 9 districts of Beijing, and the cases reported in Chaoyang district accounted for 42.22% (19/45) and in Changping district accounted for 31.11% (14/45). The age of the cholera cases ranged from 19 to 63 years. Except for one case with unknown clinical symptoms, 44 cases had diarrhea symptoms with 84.09% (37/44) of the cases reporting diarrhea (3-9 times/day), followed by yellow watery stool (95.45%, 42/44), abdominal pain (68.18%, 30/44), nausea and vomiting (40.91%, 18/44) and fever (36.36%, 16/44). Conclusion: Vibrio cholerae strains isolated in Beijing during 2015-2021 were mainly O1 serotype Ogawa,most of which were non-toxigenic. The PFGE of the strains varied. Cholera epidemics occurred in 9 districts of Beijing, but most were sporadic ones with incidence peak during June-September.

Inadequate Hand Washing, Lack of Clean Drinking Water and Latrines as Major Determinants of Cholera Outbreak in Somali Region, Ethiopia in 2019.

IntroductionCholera remains a serious public health problem characterized by a large disease burden, frequent outbreaks, persistent endemicity, and high mortality, particularly in tropical and subtropical low-income countries including Ethiopia. The recent cholera outbreak in the Somali region began on 4 September to 1 November 2019. Cholera may spread rapidly through a population so that an early detection and reporting of the cases is mandatory. This study aimed to identify determinants of cholera infection among >5 years of age population in Somali region, Ethiopia.MethodsA community-based unmatched case-control study was conducted among 228 (76 cases and 152 controls, 1:2 ratio) systematically selected population. Data were collected using a structured questionnaire administered by an interviewer and a record review. Descriptive statistics and multivariable logistic regression analysis was used to identify the determinants of the risk factors of cholera infection with a 95% confidence interval and statistical significance was declared a tap-value < 0.05.ResultsA total of 228 participants (33.3% cases and 66.7% controls) were enrolled in this study. The majority of the cases were in the range of 20–49 years of age (69.7%). The odds of acquiring cholera infection increased significantly by drinking unsafe pipe water (AOR 4.3, 95% CI 1.65–11.2), not having a household level toilet/latrine (AOR 3.25, 95% CI 1.57–6.76), hand washing only sometimes after the toilet (AOR 3.04, 95% CI 1.58–5.86) and not using water purification methods (AOR 2.3, 95% CI 1.13–4.54).ConclusionMajor risk factors for cholera infection were related to drinking water and latrine hygiene. Improvement in awareness creation about cholera prevention and control methods, including water treatment, hygiene and sanitation were crucial in combating this cholera outbreak. Primary public health actions are ensuring clean drinking water, delivery of water purification tablets, soap and hand sanitizers and provision of health care and outbreak response. Long term goals in cholera affected areas include comprehensive water and sanitation strategies. Overall, the strategic role of a multi-sectoral approach in the design and implementation of public health interventions aimed at preventing and controlling cholera are essential to avert cholera outbreaks. Preparedness should be highlighted in cholera prone areas like Somali region especially after drought periods.

The seasonality of cholera in sub-Saharan Africa: a statistical modelling study

SummaryBackgroundCholera remains a major threat in sub-Saharan Africa (SSA), where some of the highest case-fatality rates are reported. Knowing in what months and where cholera tends to occur across the continent could aid in improving efforts to eliminate cholera as a public health concern. However, largely due to the absence of unified large-scale datasets, no continent-wide estimates exist. In this study, we aimed to estimate cholera seasonality across SSA and explore the correlation between hydroclimatic variables and cholera seasonality.MethodsUsing the global cholera database of the Global Task Force on Cholera Control, we developed statistical models to synthesise data across spatial and temporal scales to infer the seasonality of excess (defined as incidence higher than the 2010–16 mean incidence rate) suspected cholera occurrence in SSA. We developed a Bayesian statistical model to infer the monthly risk of excess cholera at the first and second administrative levels. Seasonality patterns were then grouped into spatial clusters. Finally, we studied the association between seasonality estimates and hydroclimatic variables (mean monthly fraction of area flooded, mean monthly air temperature, and cumulative monthly precipitation).Findings24 (71%) of the 34 countries studied had seasonal patterns of excess cholera risk, corresponding to approximately 86% of the SSA population. 12 (50%) of these 24 countries also had subnational differences in seasonality patterns, with strong differences in seasonality strength between regions. Seasonality patterns clustered into two macroregions (west Africa and the Sahel vs eastern and southern Africa), which were composed of subregional clusters with varying degrees of seasonality. Exploratory association analysis found most consistent and positive correlations between cholera seasonality and precipitation and, to a lesser extent, between cholera seasonality and temperature and flooding.InterpretationWidespread cholera seasonality in SSA offers opportunities for intervention planning. Further studies are needed to study the association between cholera and climate.FundingUS National Aeronautics and Space Administration Applied Sciences Program and the Bill & Melinda Gates Foundation.

Identifying transferable lessons from cholera epidemic responses by M\xe9decins Sans Fronti\xe8res in Mozambique, Malawi and the Democratic Republic of Congo, 2015\u20132018: a scoping review

BackgroundCholera epidemics occur frequently in low-income countries affected by concurrent humanitarian crises. Evaluations of these epidemic response remains largely unpublished and there is a need to generate evidence on response efforts to inform future programmes. This review of MSF cholera epidemic responses aimed to describe the main characteristics of the cholera epidemics and related responses in these three countries, to identify challenges to different intervention strategies based on available data; and to make recommendations for epidemic prevention and control practice and policy.MethodsCase studies from the Democratic Republic of Congo, Malawi and Mozambique were purposively selected by MSF for this review due to the documented burden of cholera in each country, frequency of cholera outbreaks, and risk of humanitarian crises. Data were extracted on the characteristics of the epidemics; time between alert and response; and, the delivery of health and water, sanitation and hygiene interventions. A Theory of Change for cholera response programmes was built to assess factors that affected implementation of the responses.Results and conclusions20 epidemic response reports were identified, 15 in DRC, one in Malawi and four in Mozambique. All contexts experienced concurrent humanitarian crises, either armed conflict or natural disasters. Across the settings, median time between the date of alert and date of the start of the response by MSF was 23 days (IQR 14–41). Almost all responses targeted interventions community-wide, and all responses implemented in-patient treatment of suspected cholera cases in either established health care facilities (HCFs) or temporary cholera treatment units (CTUs). In three responses, interventions were delivered as case-area targeted interventions (CATI) and four responses targeted households of admitted suspected cholera cases. CATI or delivery of interventions to households of admitted suspected cases occurred from 2017 onwards only. Overall, 74 factors affecting implementation were identified including delayed supplies of materials, insufficient quantities of materials and limited or lack of coordination with local government or other agencies. Based on this review, the following recommendations are made to improve cholera prevention and control efforts: explore improved models for epidemic preparedness, including rapid mobilisation of supplies and deployment of trained staff; invest in and strengthen partnerships with national and local government and other agencies; and to standardise reporting templates that allow for rigorous and structured evaluations within and across countries to provide consistent and accessible data.

The epidemic prevention committee of the temporary capital Luoyang and its cholera control in 1932

The epidemic prevention committee of the temporary capital Luoyang was launched by the Examination Authority of the National Government in order to prevent the spread of cholera in Luoyang in August 1932. With the assistance of the ministries and commissions of both the central and local governments, the epidemic prevention committee of the temporary capital Luoyang organised a powerful anti-epidemic team and collected relatively sufficient funds and drugs for epidemic prevention, therefore, ensuring the operation of each organisation and the development of epidemic prevention mechanisms. Meanwhile, it took two strategies for epidemic prevention in terms of treatment and prevention. The infected patients were given medical treatment on the one hand; Active prevention strategies were developed on the other, such as vaccination, water disinfection and epidemic prevention propaganda. The two strategies effectively controlled the spread of cholera in Luoyang and its surrounding areas. It was found that such effective cholera control was determined by the particular and political identity of Luoyang as the temporary capital at that time, and the strong support from diverse organisations and departments as well.

Evolutionary Sweeps of Subviral Parasites and Their Phage Host Bring Unique Parasite Variants and Disappearance of a Phage CRISPR-Cas System.

ABSTRACTVibrio cholerae is a significant threat to global public health in part due to its propensity for large-scale evolutionary sweeps where lineages emerge and are replaced. These sweeps may originate from the Bay of Bengal, where bacteriophage predation and the evolution of antiphage counterdefenses is a recurring theme. The bacteriophage ICP1 is a key predator of epidemic V. cholerae and is notable for acquiring a CRISPR-Cas system to combat PLE, a defensive subviral parasite encoded by its V. cholerae host. Here, we describe the discovery of four previously unknown PLE variants through a retrospective analysis of >3,000 publicly available sequences as well as one additional variant (PLE10) from recent surveillance of cholera patients in Bangladesh. In recent sampling we also observed a lineage sweep of PLE-negative V. cholerae occurring within the patient population in under a year. This shift coincided with a loss of ICP1’s CRISPR-Cas system in favor of a previously prevalent PLE-targeting endonuclease called Odn. Interestingly, PLE10 was resistant to ICP1-encoded Odn, yet it was not found in any recent V. cholerae strains. We also identified isolates from within individual patient samples that revealed both mixed PLE(+)/PLE(−) V. cholerae populations and ICP1 strains possessing CRISPR-Cas or Odn with evidence of in situ recombination. These findings reinforce our understanding of the successive nature of V. cholerae evolution and suggest that ongoing surveillance of V. cholerae, ICP1, and PLE in Bangladesh is important for tracking genetic developments relevant to pandemic cholera that can occur over relatively short timescales.

Dynamical behavior and optimal control of a stochastic mathematical model for cholera

A stochastic cholera model with saturation recovery rate is discussed. Firstly, the existence and uniqueness of the global positive solution of the system are proved. Secondly, the asymptotic behavior of the solutions of the stochastic cholera model near the disease-free equilibrium and the corresponding deterministic endemic equilibrium is discussed. Then, the phenomenon that the large noise can cause the extinction of cholera is obtained. Furthermore, on the basis of the stochastic model, the optimal control is added and studied to provide a theoretical basis for the prevention and control of cholera. Finally, the theoretical results are verified by numerical simulations and some suggestions on how to better control the disease are presented.

Analysis of Cholera model with treatment noncompliance

A model for transmission dynamics of cholera infection between human host and environment is developed. We incorporate the proportion of infectious individuals who do not comply with treatment into the human population. Stability analysis, as well as simulation of the model, is done. The results from the stability analysis show that the disease-free equilibrium solution is locally asymptotically stable if R0 1. The technical tool used for our analysis is the theory of competitive systems, compound matrices and stability of periodic orbits. Finally, we investigate, numerically, the influence of seasonal variation on the control of cholera.

The 2021 Cholera Outbreak in West Africa: Epidemiology and Public Health Implications

Introduction: Cholera is one of the most frequent public health emergencies in Sub Saharan Africa. The disease is targeted for elimination by the World Health Organization and the Global Task Force on Cholera Control.

Environmental Impacts of Pesticides - A Review

Pesticides are applied in various sectors such as agriculture, domestic, material building, personal and public health for control of weeds, pests, rodents; household and garden spray, control of animals and birds; incorporation of paints, glues, plastic protection sheeting; for application of clothing and skincare; and for control of malaria, dengue fever and cholera. In agriculture, chemicals are purposefully discharged into the environment. Application of pesticides in agriculture is a subcategory of the largest group of manufactured compounds used in the present world. Excessive and inappropriate use of pesticides has resulted in contamination of environment. Pesticides are degraded into organic micro pollutants that have negative effects on the environment. By the mechanism of biomagnification and bioconcentration, they cause deleterious effects on the living organisms. Ecological impacts of pesticides are different but they are chronic and inter-related. During precipitation, pesticides from land, float to aquatic systems and become harmful to fishes, birds, non-target creatures, etc. They also interact with injurious algal blooms, which enhances the original poisonous nature of the pesticides. This review focuses on environmental impacts of pesticides on contamination of water, fate, effects and behaviour in the environment, effects of contamination on natural resources, food safety, non-target organisms and threats to biodiversity. This study recommends application of suitable amounts of less harmful formulation of pesticides, as and when required.

A SIQRB delayed model for cholera and optimal control treatment

We improve a recent mathematical model for cholera by adding a time delay that represents the time between the instant at which an individual becomes infected and the instant at which he begins to have symptoms of cholera disease. We prove that the delayed cholera model is biologically meaningful and analyze the local asymptotic stability of the equilibrium points for positive time delays. An optimal control problem is proposed and analyzed, where the goal is to obtain optimal treatment strategies, through quarantine, that minimize the number of infective individuals and the bacterial concentration, as well as treatment costs. Necessary optimality conditions are applied to the delayed optimal control problem, with a L1 type cost functional. We show that the delayed cholera model fits better the cholera outbreak that occurred in the Department of Artibonite - Haiti, from 1 November 2010 to 1 May 2011, than the non-delayed model. Considering the data of the cholera outbreak in Haiti, we solve numerically the delayed optimal control problem and propose solutions for the outbreak control and eradication.

Cholera Prevention, Control Strategies, Challenges and World Health Organization Initiatives in the Eastern Mediterranean Region: A Narrative Review

Cholera Prevention, Control Strategies, Challenges and World Health Organization Initiatives in the Eastern Mediterranean Region: A Narrative Review

Optimal Strategies for the Control of Cholera with Three Infection Routes

Cholera is an acute intestinal infection and water borne disease that has claimed and continue to claim the lives of millions of people in the developing countries. Its effects on developing countries cannot be ignored since most of the people who get infected or die from the disease are usually children and adults who are in their economically active years. This paper presents an epidemic mathematical model that is aimed at describing the dynamics of the spread of Cholera. In this paper, infection of the disease is considered to be through contact with Infectives or vibrio cholerae in the dry lands and the water bodies. The model is qualitatively analyzed to determine conditions for successful fight against cholera. It is shown that if the basic reproduction number , is less than unity, then the disease-free equilibrium is locally asymptotically stable and the disease dies out and when the basic reproduction number is greater than unity, the vibrio cholerae and the disease will persist in the population. Numerical simulations are also carried out and various combinations of intervention strategies are compared to determine the most effective strategy that should be employed in order to control the spread of the v.cholerae. It is observed that the strategy that adopts education on open defecation, environmental sanitation and water treatment are the most effective strategies in the fight against the spread of the disease Keywords and phrases: Mathematical model, local stability, basic reproduction number, optimal control. DOI: 10.7176/MTM/12-1-02 Publication date: January 31 st 2022