Cholera Prevention Research Articles

An overview of cholera vaccines and their public health implications

The current cholera pandemic now involves almost the entire developing world and represents an important global challenge. Though improved water and sanitation remain the mainstays of cholera prevention efforts, major improvements to infrastructure continue to be a goal far out of reach for many of those affected and near-term interventions, including vaccines, need consideration. Prolonged and frequent epidemics, increased antimicrobial resistance, and heightening awareness of the role of climate change in disease burden have returned cholera to the forefront of the international public health forum. The availability of new oral cholera vaccines and supporting data have prompted the WHO to recommend vaccination be used with other prevention and control strategies where disease is endemic, and their use should be considered in outbreak situations. Vibrio cholerae, a highly transmissible organism, is found in aquatic reservoirs and is not an eradicable disease. New variant strains appear to cause more severe clinical disease, and may be displacing earlier seventh pandemic organisms as the major cause of cholera. Licensed newer-generation oral vaccines have proven to be well tolerated, protective (including against new variant strains), and affordable and offer a new tool to control cholera.

Cholera: Lessons from Haiti and Beyond

Cholera is an acute, severe diarrheal disease caused by Vibrio cholerae that affects millions of people each year. Without prompt rehydration, death can occur within hours of the onset of symptoms. In October 2010, cholera emerged in Haiti, and the resulting large epidemic continues today. As of August 29, 2011, more than 439,000 cases have been reported in Haiti, with over 6,200 deaths. This review covers important features of epidemiology, pathogenesis, treatment and prevention of cholera, with a focus on the ongoing epidemic in Haiti.

Knowledge, Attitudes, and Practices Related to Treatment and Prevention of Cholera, Haiti, 2010

In response to the recent cholera outbreak, a public health response targeted high-risk communities, including resource-poor communities in Port-au-Prince, Haiti. A survey covering knowledge and practices indicated that hygiene messages were received and induced behavior change, specifically related to water treatment practices. Self-reported household water treatment increased from 30.3% to 73.9%.

Cholera Management and Prevention at Hôpital Albert Schweitzer, Haiti

Abstract In October 2010, Hôpital Albert Schweitzer Haiti treated some of the first patients with cholera in Haiti. Over the following 10 months, a strategic plan was developed and implemented to improve the management of cases at the hospital level and to address the underlying risk factors at the community level.

Cholera Prevention Training Materials for Community Health Workers, Haiti, 2010–2011

Stopping the spread of the cholera epidemic in Haiti required engaging community health workers (CHWs) in prevention and treatment activities. The Centers for Disease Control and Prevention collaborated with the Haitian Ministry of Public Health and Population to develop CHW educational materials, train >1,100 CHWs, and evaluate training efforts.

Epidemic cholera in a crowded urban environment, Port-au-Prince, Haiti.

We conducted a case–control study to investigate factors associated with epidemic cholera. Water treatment and handwashing may have been protective, highlighting the need for personal hygiene for cholera prevention in contaminated urban environments. We also found a diverse diet, a possible proxy for improved nutrition, was protective against cholera.

The case of cholera preparedness, response and prevention in the SADC region: A need for proactive and multi-level communication and co-ordination

In this paper the authors seek to identify the most appropriate model for a regional co-ordination mechanism for cholera preparedness, response and prevention. The qualitative mixed-method data collection approach that was followed revealed the need for alternative solutions, including a socio-political understanding of cholera responses at different levels of scale and at different stages of an outbreak. Important areas that need to be understood include the multiplicity of actors and the complexity of their interaction, the importance of building local capacity, the need for varying responses at different levels of scale, the need for improved inter- and intra-country co-ordination and information exchange, the importance of cultural belief systems and the impact of the media on the response to cholera outbreaks. Ultimately, despite the proposed co-ordinating role that the Southern African Development Community (SADC) can play in a regional cholera response effort, the onus remains on states to build capacity at the local level and to capacitate local communities to drive response efforts semi-autonomously. Keywords: Cholera prevention, preparedness and response, socio-political understanding of cholera, socio-cultural understanding of cholera, transboundary disease, Southern African Development Community (SADC), cholera

Cholera in the 21st century

This review will focus on recent advances in our understanding of biologic and environmental factors that shape current cholera outbreaks, advances in our understanding of host-pathogen interactions during cholera, and recent evolution of current treatment and cholera prevention strategies. New research studies have improved our understanding of a number of dynamic factors that shape the ecology of Vibrio cholerae and influence its transmission, including the role of lytic bacteriophage, biofilm formation, a hyperinfectious state of human-passaged V. cholerae, and the impact of severe weather events. Provision of safe water and improved sanitation continue to be the mainstays of preventing cholera transmission; however, the role of cholera vaccination as a control measure in both endemic and epidemic settings is evolving. Recent advances in our understanding of long-lived protective immunity after natural infection may aid in the global efforts to control cholera. Improved understanding of factors associated with protective immunity and dynamic factors associated with cholera outbreaks may lead to improved control and prevention strategies for cholera.

A cholera outbreak among semi-nomadic pastoralists in northeastern Uganda: epidemiology and interventions

In sub-Saharan Africa, many nomadic pastoralists have begun to settle in permanent communities as a result of long-term water, food, and civil insecurity. Little is known about the epidemiology of cholera in these emerging semi-nomadic populations. We report the results of a case-control study conducted during a cholera outbreak among semi-nomadic pastoralists in the Karamoja sub-region of northeastern Uganda in 2010. Data from 99 cases and 99 controls were analysed. In multivariate analyses, risk factors identified were: residing in the same household as another cholera case [adjusted odds ratio (aOR) 6·67, 95% confidence interval (CI) 2·83-15·70], eating roadside food (aOR 2·91, 95% CI 1·24-6·81), not disposing of children's faeces in a latrine (aOR 15·76, 95% CI 1·54-161·25), not treating drinking water with chlorine (aOR 3·86, 95% CI 1·63-9·14), female gender (aOR 2·43, 95% CI 1·09-5·43), and childhood age (10-17 years) (aOR 7·14, 95% CI 1·97-25·83). This is the first epidemiological study of cholera reported from a setting of semi-nomadic pastoralism in sub-Saharan Africa. Public health interventions among semi-nomadic pastoralists should include a two-faceted approach to cholera prevention: intensive health education programmes to address behaviours inherited from insecure nomadic lifestyles, as well as improvements in water and sanitation infrastructure. The utilization of community-based village health teams provides an important method of implementing such activities.

Would Cholera become a Neglected Tropical Disease?

Cholera is a serious public health problem, particularly in Africa, Asia, South and Central America. Similar to the neglected tropical diseases (NTD), it is common in places with unsafe water, poor sanitation and limited access to the basic health care. In the concurrent times when the world is shrinking into a Global village, the definition of NTD itself has lost significance owing to rapid transmission of such diseases. Even, the cholera non-endemic developed countries in Europe, Russia and Oceania have become vulnerable to imported cholera. The seventh pandemic of cholera is in its 51st year without any sign of abatement despite improvements in sanitation, safe drinking water supply, promotion of oral rehydration therapy and availability of alternative preventive interventions like oral cholera vaccines. Cholera is markedly under reported due to a myriad of reasons including economic ones. The under reporting is also resulted from weakening surveillance system across countries which in turn contributes to changing perceptions and attitudes on burden of the disease and deteriorating public health services. In addition to this, lack of evidence-based sector wide programmatic approach and inequitable resource allocation for prevention and control of cholera may also risk the disease to become a NTD in future.

Meeting Cholera's Challenge to Haiti and the World: A Joint Statement on Cholera Prevention and Care

Cholera in Haiti: Acute-on-Chronic Long before the devastating earthquake on January 12, 2010, Haiti struggled beneath the burdens of intractable poverty and ill health. The poorest country in the Western Hemisphere, Haiti also faces some of the highest rates of maternal and infant mortality—widely used indicators of the robustness of a health system—in the world ([S1] in Text S1; [2], [3]). The October 2010 cholera outbreak is the most recent of a long series of affronts to the health of Haiti's population; it is yet another acute symptom of the chronic weakness of Haiti's health, water, and sanitation systems. Water and sanitation conditions highlight these systemic weaknesses. In 2002, Haiti ranked last out of 147 countries for water security [4], [5]. Before the earthquake struck, only half of the population in the capital, Port-au-Prince, had access to latrines or other forms of modern sanitation, and roughly one-third had no access to tap water [6]. Across the country, access to sanitation and clean water is even more limited: only 17% of Haitians had access to adequate sanitation in 2008, and 12% received treated water [7]. Not surprisingly, diarrheal diseases have long been a significant cause of death and disability, especially among children under 5 years of age [6]. The cholera outbreak began less than a year after a 7.0-magnitude earthquake took the lives of more than 300,000 people and left nearly 1.5 million homeless [6]. Almost 1 million Haitians still live in spontaneous settlements known as internally displaced persons (IDP) camps [8]. While post-earthquake conditions in Haiti were ripe for outbreaks of acute diarrheal illness, cholera was deemed “very unlikely to occur” by the United States Centers for Disease Control and Prevention (CDC) and other public health authorities [9]. Cholera had never before been reported in Haiti [S2] [10], [11]; health providers were unprepared for an influx of patients presenting with acute watery diarrhea. The cholera epidemic has been most severe in rural areas and large urban slums. Rural communities were charged with hosting hundreds of thousands of displaced people after the earthquake, placing greater demands on their already-scarce resources, including water. Surface water drawn directly from the source or piped from rivers and streams constitutes the principal supply of drinking water in rural Haiti. The lack of adequate piping, filtration, and water treatment systems (including chlorination) made these rural regions vulnerable to the rapid spread of waterborne disease. While most IDP camps have been supplied with potable water, large urban slums have had to rely on existing water sources—some of them containing Vibrio cholerae—and have therefore been vulnerable to rapid disease spread. Most slums also have poor sanitation infrastructure. Since the first cases were reported in Saint-Marc and Mirebalais, cholera has spread to every department in Haiti, and to other countries, too [S3] [12]–[14]. Public suspicion (ultimately validated by genomic sequence analyses [15]) of the strain's link to South Asia, home to a group of United Nations peacekeepers stationed in central Haiti, triggered blame and violence that interfered with response efforts. As we have learned from the global AIDS pandemic and other infectious disease epidemics, cycles of accusation can continue for years, diverting attention and resources from the delivery of care and prevention services [16]. Systemic problems that brought cholera to epidemic levels in Haiti will (unless addressed) continue to facilitate its spread. As a disease of poverty, cholera preys upon the bottom of the social gradient; international trade, migration, and travel—from South Asia or elsewhere—open direct channels for pathogens that follow social fault lines.

Revived interest in bacteriophages

Summary Phages have a track record of being left behind whenever science moves on to other things. But will the inexorable spread of antibiotic resistance lead to a revival of their role as antibacterial therapeutics? Michael Gross investigates.

Risk factors associated with cholera in Harare City, Zimbabwe, 2008

Two suspected cholera cases at Beatrice Road Infectious Diseases Hospital were reported to Harare City Health Department on 14 October 2008 setting in motion investigation and control measures. We determined the extent of the epidemic and risk factors for contracting cholera. An unmatched 1:1 case-control study was conducted. Any resident of Harare City, 2 years and above, with acute watery diarrhoea, with or without vomiting from 30 October 2008 to 01 December 2008. Any resident of Harare City, 2 years and above, neighbour to a case, who did not contract cholera during the same period. From 14 October 2008 to 21 January 2009, 11203 cases were reported with a case fatality rate (CFR) of 3.98%. We interviewed 140 cases and 140 controls. Median age was 28 years (Q1 = 20; Q3 = 37.5) and 28.5 years (Q1 = 23; Q3 = 38) for cases and controls respectively. Having a diarrhoea contact at home [AOR = 12.02; 95% CI (5.46 - 26.44)], having attained less than secondary education [AOR = 4.40; 95% CI (2.28 - 8.48)]; eating cold food [AOR = 4.24; 95% CI (1.53 - 11.70)] were independent risk factors while drinking tap water [AOR = 0.05; 95% CI (0.03 - 0.11)], washing hands after using toilet [AOR = 0.19; 95% CI (0.09 - 0.39)]; eating hot food always [AOR= 0.29; 95% CI (0.17 - 0.49)] were independently protective factors. The high CFR may be due to poor case management and staff shortage in treatment camps. Th e cholera outbreak in Harare resulted from poor personal and hygiene practices that occur when water supplies are cut. Lack of water, low knowledge on cholera prevention measures and delays in community health education campaigns contributed to the protracted outbreak. Having a diarrhoea contact at home increases chances of household members acquiring infection. Provision of safe drinking water, community health education, recruitment of staff and training of health workers on cholera case management must be prioritized.

Strategic framework for cholera prevention and control in Chengdu: construction and effectiveness evaluation

To construct an operable strategic framework for cholera prevention and control which mobilized the advantages of local resources and adapted to social developments in Chengdu, and to evaluate its application effects. (1) After analyzing the local epidemic data of cholera in Chengdu from 1994 to 2004, we determined the main problems of cholera prevention and control works as well as the efficiency and deficiency of employed measures, and then formed a basic strategic framework. (2) After 55 invited experts preliminarily scored the strategic framework, we selected 72 specific measures to establish a measure entry database, and then the importance and operability of each measure were scored by 17 core experts. (3) Finally, the effectiveness of this strategic framework was evaluated according to the analyzing results of infection control, health education and etiological monitoring. (1) The framework took government leadership as main scenario and the informatization as subordination scenario. Meanwhile, it focused on three points: the improvement of social environment, the completion of system and mechanisms for monitoring and early warning, and the enhancement of CDC response to public health emergencies. Total importance score and operability score of 35 specific measures included in this framework was 4.20 ± 0.86 and 4.09 ± 0.87, respectively. (2) Chengdu had maintained zero cholera incidence for five consecutive years from 2005 to 2009 since it gradually began to implement the strategic framework in 2002. There were 19 positive cholera cases detected by etiological monitoring and all of them were seafood or fishery products including soft-shelled turtles, silver carps and bullfrogs. The coverage rate and qualification rate of the training for grassroots cadres, grassroots medical workers, mobile cooks and their assistants was 98.14% (198 452/202 220) and 98.17% (194 820/198 452) in average, respectively. The qualification rate of the training for employees in food industry was over 96.00% (912 470/950 489). The average awareness rate of cholera prevention and cure knowledge in rural residents, grassroots cadres, grassroots medical workers, mobile cooks and their assistants was 93.87% (1653/1761) and the average formation rate of good hygiene habits was 70.58% (1243/1761). A strategic framework suitable for cholera prevention and control in Chengdu has been successfully established in this study. The incidence rate of cholera has maintained zero in Chengdu for five consecutive years under incessant threatening conditions such as the occurrence of cholera cases from time to time in its surrounding areas and the continuous existence of Bacillus comma in seafood or fishery products that entered local markets. Therefore, it demonstrated a good application effects.

The case for reactive mass oral cholera vaccinations.

IntroductionThe outbreak of cholera in Zimbabwe intensified interest in the control and prevention of cholera. While there is agreement that safe water, sanitation, and personal hygiene are ideal for the long term control of cholera, there is controversy about the role of newer approaches such as oral cholera vaccines (OCVs). In October 2009 the Strategic Advisory Group of Experts advised the World Health Organization to consider reactive vaccination campaigns in response to large cholera outbreaks. To evaluate the potential benefit of this pivotal change in WHO policy, we used existing data from cholera outbreaks to simulate the number of cholera cases preventable by reactive mass vaccination.MethodsDatasets of cholera outbreaks from three sites with varying cholera endemicity—Zimbabwe, Kolkata (India), and Zanzibar (Tanzania)—were analysed to estimate the number of cholera cases preventable under differing response times, vaccine coverage, and vaccine doses.FindingsThe large cholera outbreak in Zimbabwe started in mid August 2008 and by July 2009, 98,591 cholera cases had been reported with 4,288 deaths attributed to cholera. If a rapid response had taken place and half of the population had been vaccinated once the first 400 cases had occurred, as many as 34,900 (40%) cholera cases and 1,695 deaths (40%) could have been prevented. In the sites with endemic cholera, Kolkata and Zanzibar, a significant number of cases could have been prevented but the impact would have been less dramatic. A brisk response is required for outbreaks with the majority of cases occurring during the early weeks. Even a delayed response can save a substantial number of cases and deaths in long, drawn-out outbreaks. If circumstances prevent a rapid response there are good reasons to roll out cholera mass vaccination campaigns well into the outbreak. Once a substantial proportion of a population is vaccinated, outbreaks in subsequent years may be reduced if not prevented. A single dose vaccine would be of advantage in short, small outbreaks.ConclusionsWe show that reactive vaccine use can prevent cholera cases and is a rational response to cholera outbreaks in endemic and non-endemic settings. In large and long outbreaks a reactive vaccination with a two-dose vaccine can prevent a substantial proportion of cases. To make mass vaccination campaigns successful, it would be essential to agree when to implement reactive vaccination campaigns and to have a dynamic and determined response team that is familiar with the logistic challenges on standby. Most importantly, the decision makers in donor and recipient countries have to be convinced of the benefit of reactive cholera vaccinations.

Development of multiplex real time PCR methodology for better identification and discrimination of Vibrio cholerae and O139 serotype

To develop a rapid, sensitive and specific assay method, based on multiplex real time PCR for identifying Vibrio cholerae and distinguishing Vibrio cholerae O139 serotype from Vibrio cholerae. Cholera toxin A subunit gene (ctxA) and glycosyltransferase gene (LPSgt) were chosen as targets according to Vibrio cholerae and Vibrio cholerae O139 serotype, and then the primers and TaqMan-MGB probe were designed. The 5'end of probes was labeled with FAM and VIC fluoresceins respectively while the 3'end of probes was labeled with MGB. The PCR reaction was optimized systematically. Then the specificity, sensitivity and reproducibility of multiplex real time PCR were estimated. Finally, multiplex real time PCR was applied to detect the clinical specimens. Vibrio cholerae was identified by multiplex real time PCR accurately and quickly, which could distinguish Vibrio cholerae O139 serotype from Vibrio cholerae. Vibrio cholerae was identified positive for primer pairs and probes from ctxA gene, and Vibrio cholerae O139 serotype tested was positive for LPSgt gene. Meanwhile, none of other bacteria was identified. Sensitivity of the test was 2 × 10(2) cfu/ml. When this assay was applied directly to identify 45 clinical specimens, results showed that 10 were positive to Vibrio cholerae, in which 4 clinical specimens were positive to Vibrio cholerae O139 serotype. All the results were the same to the one that had been obtained from the conventional assays. Our results showed that the multiplex real time PCR was a reliable, accurate and feasible method for identifying Vibrio cholerae that carrying toxin gene and distinguishing Vibrio cholerae O139 serotype from Vibrio cholerae. This method could be applied to the cholera surveillance, prevention and control system for identifying and distinguishing Vibrio cholerae in the labs.

Principles of antidote pharmacology: an update on prophylaxis, post‐exposure treatment recommendations and research initiatives for biological agents

The use of biological agents has generally been confined to military-led conflicts. However, there has been an increase in non-state-based terrorism, including the use of asymmetric warfare, such as biological agents in the past few decades. Thus, it is becoming increasingly important to consider strategies for preventing and preparing for attacks by insurgents, such as the development of pre- and post-exposure medical countermeasures. There are a wide range of prophylactics and treatments being investigated to combat the effects of biological agents. These include antibiotics (for both conventional and unconventional use), antibodies, anti-virals, immunomodulators, nucleic acids (analogues, antisense, ribozymes and DNAzymes), bacteriophage therapy and micro-encapsulation. While vaccines are commercially available for the prevention of anthrax, cholera, plague, Q fever and smallpox, there are no licensed vaccines available for use in the case of botulinum toxins, viral encephalitis, melioidosis or ricin. Antibiotics are still recommended as the mainstay treatment following exposure to anthrax, plague, Q fever and melioidosis. Anti-toxin therapy and anti-virals may be used in the case of botulinum toxins or smallpox respectively. However, supportive care is the only, or mainstay, post-exposure treatment for cholera, viral encephalitis and ricin - a recommendation that has not changed in decades. Indeed, with the difficulty that antibiotic resistance poses, the development and further evaluation of techniques and atypical pharmaceuticals are fundamental to the development of prophylaxis and post-exposure treatment options. The aim of this review is to present an update on prophylaxis and post-exposure treatment recommendations and research initiatives for biological agents in the open literature from 2007 to 2009.

Hormoz Ebrahimnejad (ed.), The development of modern medicine in non-western countries: historical perspectives, Royal Asiatic Society Books, London and New York, Routledge, 2009, pp. xiv, 241, £80.00 (hardback 978-0-415-44742-3).

Hormoz Ebrahimnejad (ed.), The development of modern medicine in non-western countries: historical perspectives, Royal Asiatic Society Books, London and New York, Routledge, 2009, pp. xiv, 241, £80.00 (hardback 978-0-415-44742-3). - Volume 54 Issue 2

A influenza invisível: a resposta comunitária à pandemia de 1918-1920 no norte rural da Suécia

Ao longo da história humana, pandemias recorrentes de influenza têm afetado indivíduos e sociedades em todo o mundo. No entanto, as respostas sociais têm variado no tempo e no espaço. Este artigo discute a resposta da sociedade à influenza espanhola de 1918-1920 no norte rural da Suécia, focando as medidas tomadas pelas comunidades locais para fazer frente à pandemia que avançava. Nas cinco comunidades rurais estudadas, a resposta oficial foi esparsa e reativa, e a presença da influenza pandêmica é quase invisível nos registros municipais. Medidas preventivas em potencial, tais como o fechamento de escolas e proibições de aglomerações públicas, foram utilizadas inadequadamente e introduzidas tarde demais para que fossem eficazes. Como algumas explicações para a aparente inércia das autoridades locais durante a influenza espanhola sugerem-se a luta, então corrente, contra as privações de uma época de guerra, a crise de alimentos somada a uma economia tensa, uma insuficiente administração pública de saúde, uma política pública nacional preventiva que almejava primordialmente à prevenção da cólera e o uso continuado de métodos tradicionais para se lidar com crise na sociedade.

Dual peak cholera transmission in Bengal Delta: A hydroclimatological explanation

Cholera has reemerged as a global killer with the world witnessing an unprecedented rise in cholera infection and transmission since the 1990s. Cholera outbreaks across most affected areas show infection patterns with a single annual peak. However, cholera incidences in the Bengal Delta region, the native homeland of cholera, show bi‐annual peaks. The mechanisms behind this unique seasonal dual peak phenomenon in cholera dynamics, especially the role of climatic and hydrologic variables, are not fully understood. Here, we show that low flow in the Brahmaputra and the Ganges during spring is associated with the first outbreaks of cholera in Bangladesh; elevated spring cholera outbreaks are seen in low discharge years. Peak streamflow of these rivers, on the other hand, create a different cholera transmission environment; peak flood volumes and extent of flood‐affected areas during monsoon are responsible for autumn cholera outbreaks. Our results demonstrate how regional hydroclimatology may explain the seasonality and dual peaks of cholera incidence in the Bengal Delta region. A quantitative understanding of the relationships among the hydroclimatological drivers and seasonal cholera outbreaks will help early cholera detection and prevention efforts.