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January 2017

GAAC's newsletter N°1 - March 2016

Auteurs : Aurélie Jeandron, Jaime Mufitini Saidi, Alois Kapama, Manu Burhole, Freddy Birembano, Thierry Vandevelde, Antonio Gasparrini, Ben Armstrong, Sandy Cairncross, Jeroen H. J. Ensink. PLOS Medicine.

Auteur(s): S. Rebaudet | B. Sudre | B. Faucher | R. Piarroux - Date de Publication: 2013-10-07 - Publication: Journal of Infectious Diseases - Resumé: Cholera is generally regarded as the prototypical waterborne and environmental disease. In Africa, available studies are scarce, and the relevance of this disease paradigm is questionable. Cholera outbreaks have been repeatedly reported far from the coasts: from 2009 through 2011, three-quarters of all cholera cases in Africa occurred in inland regions. Such outbreaks are either influenced by rainfall and subsequent floods or by drought- and water-induced stress. Their concurrence with global climatic events has also been observed. In lakes and rivers, aquatic reservoirs of Vibrio cholerae have been evocated. However, the role of these reservoirs in cholera epidemiology has not been established. Starting from inland cholera-endemic areas, epidemics burst and spread to various environments, including crowded slums and refugee camps. Human displacements constitute a major determinant of this spread. Further studies are urgently needed to better understand these complex dynamics, improve water and sanitation efforts, and eliminate cholera from Africa.

Auteur(s): J. J. Muyembe | D. Bompangue | G. Mutombo | L. Akilimali | A. Mutombo | B. Miwanda | J. d. D. Mpuruta | K. K. Deka | F. Bitakyerwa | J. M. Saidi | A. L. Mutadi | R. S. Kakongo | F. Birembano | M. Mengel | B. D. Gessner | B. K. Ilunga - Date de Publication: 2013-10-07 - Publication: Journal of Infectious Diseases - Resumé: We evaluated published and unpublished data on cholera cases and deaths reported from clinical care facilities in the 56 health districts of the Democratic Republic of Congo to the National Ministry of Health during 2000–2011. Cholera incidence was highest in the eastern provinces bordering lakes and epidemics primarily originated in this region. Along with a strong seasonal component, our data suggest a potential Vibrio cholerae reservoir in the Rift Valley lakes and the possible contribution of the lakes’ fishing industry to the spread of cholera. The National Ministry of Health has committed to the elimination—rather than control—of cholera in DRC and has adopted a new national policy built on improved alert, response, case management, and prevention. To achieve this goal and implement all these measures it will require strong partners in the international community with a similar vision.

Auteur(s): S. Rebaudet | B. Sudre | B. Faucher | R. Piarroux - Date de Publication: 2013-10-07 - Publication: Journal of Infectious Diseases - Resumé: According to the “cholera paradigm,” epidemiology of this prototypical waterborne disease is considered to be driven directly by climate-induced variations in coastal aquatic reservoirs of Vibrio cholerae. This systematic review on environmental determinants of cholera in coastal Africa shows that instead coastal epidemics constitute a minor part of the continental cholera burden. Most of coastal cholera foci are located near estuaries, lagoons, mangrove forests, and on islands. Yet outbreaks often originate in coastal cities, where cholera is more likely to be imported from distant areas. Cholera outbreaks also may intensify in densely populated slum quarters before spreading to adjacent regions. Frequent seasonality of cholera incidence appears driven by the rainfall-induced contamination of unprotected water sources through latrine overflow and sewage, as well as by the periodicity of human activities like fishing or traveling. Lulls in transmission periods of several years are repeatedly recorded even in high-risk coastal areas. To date, environmental studies have failed to demonstrate a perennial aquatic reservoir of toxigenic V. cholerae around the continent. Finally, applicability of the cholera paradigm therefore appears questionable in Africa, although available data remain limited. Thorough surveys with microbiological analyses of water samples and prospective genotyping of environmental and clinical strains of V. cholerae are needed to understand determinants of cholera in coastal Africa and better target prevention and control measures.

Auteur(s): UNICEF - Date de Publication: 2013 - Resumé: The Toolkit provides the health and WASH sectors an integrated approach to cholera prevention, preparedness and response. In addition it includes specific content linked to education, nutrition, communication for development (C4D), child protection and other relevant sectors.

Auteur(s): Ronald J. Waldman | Eric D. Mintz | Heather E. Papowitz Date de Publication: 2013-02-14Publication: New England Journal of Medicine Resumé: Whenever epidemics of cholera occur, the global public health community is energized. Experts meet, guidelines for control are reviewed and reissued, and new and modified interventions are proposed and promoted. In the past two decades, these things happened after cholera appeared in Latin America in 1991, in the wake of the Rwandan genocide and the ensuing refugee crisis in Zaire (now Democratic Republic of Congo) in 1994, in Zimbabwe in 2008, and in October 2010, at the onset of the ongoing epidemic in Haiti (see article by Barzilay et al.). But even when it is not covered in the news or noticed by the public, cholera occurs regularly in the developing world, and the annual number of cases reported to the World Health Organization (WHO) has increased over the past few years to more than half a million cases and 7816 related deaths reported from all regions in 2011. Moreover, these reported numbers grossly underestimate the actual global burden of cholera: the WHO estimates that 3 million to 5 million cases and 100,000 to 200,000 deaths due to cholera occur annually.

Auteur(s): Jason B Harris | Regina C LaRocque | Firdausi Qadri | Edward T Ryan | Stephen B Calderwood - Date de Publication: 2012-06-30 - Publication: The Lancet - Resumé: Cholera is an acute, secretory diarrhoea caused by infection with Vibrio cholerae of the O1 or O139 serogroup. It is endemic in more than 50 countries and also causes large epidemics. Since 1817, seven cholera pandemics have spread from Asia to much of the world. The seventh pandemic began in 1961 and affects 3—5 million people each year, killing 120 000. Although mild cholera can be indistinguishable from other diarrhoeal illnesses, the presentation of severe cholera is distinct, with pronounced diarrhoeal purging. Management of patients with cholera involves aggressive fluid replacement; effective therapy can decrease mortality from more than 50% to less than 0•2%. Antibiotic treatment decreases volume and duration of diarrhoea by 50% and is recommended for patients with moderate to severe dehydration. Prevention of cholera depends on access to safe water and sanitation. Two oral cholera vaccines are available and the most effective use of these in integrated prevention programmes is being actively assessed.

Auteur(s): Global Alliance Against Cholera - Date de Publication: 2011-01 - Institution: Global Alliance Against Cholera - Resumé: This new strategy to eliminate cholera in the Democratic Republic of Congo (DRC), and other affected countries, includes but goes far beyond the traditional emergency medical response to cholera epidemics. This proposed new paradigm will effectively eliminate cholera and other waterborne contagious diseases by analyzing, securing, and reinforcing access to potable water, health education, and effective sanitation services for at risk populations. The new paradigm is based on two interrelated principles: i) Enforcement of epidemiological surveillance in at risk populations, including the screening of suspected cases, through which laboratory confirmation will identify the pattern of the spread of the disease; and ii) Designation of sanctuary zones in which the provision of potable water, focused health education and effective sanitation facilities will be assured for vulnerable areas in which the cholera epidemics are likely to emerge. These actions will only be successful given a proper and timely transfer of technical competencies to the local health service personnel, and the launch of effective public health information campaigns about cholera contamination factors that must be understood by the “at risk” local communities.

Auteur(s): R. Piarroux | D. Bompangue | P. Y. Oger | F. Haaser | A. Boinet | T. Vandevelde - Date de Publication: 2009 - Publication: Field Actions Science Reports - Resumé: The Democratic Republic of Congo (DRC) is the country in the world which reported the highest number of cholera cases to WHO from 2002 to 2007 (128 936 cases out of a worldwide 902 071 cases). We, therefore, implemented research work which intends to understand the epidemiology of cholera in the DRC and to ensure improvements in the strategy to fight against cholera. This broad study enabled us to accurately determine the cholera epidemic's mechanisms on different scales; to identify the source zones of the disease, and the groups of populations acting as vectors of the spread. It was then possible to demonstrate the role of "sanctuary'', played by some suburbs of lakeside cities. A collaborative network, including several scientific institutions in Europe and in the DRC, local and national government administrations in the field of public health and sanitation, international agencies, NGOs and private foundations, was progressively set up. Following the conclusions of our epidemiological studies, a drastic change of strategy was proposed: the limited curative approach on the one hand, the few existing water/sanitation programs on the other hand, have been merged in a global approach involving a larger scale water and sanitation infrastructure improvement, environmental protection, hygiene awareness and medical surveys targeting a few focus areas playing a central role in the epidemics. In conclusion, by better targeting intervention zones, one can gather human and technical resources previously scattered on the vast territory of the DRC. The strategy presented here revives the hope to eliminate cholera in the DRC.

Auteur(s): Guillaume Constantin de Magny | Raghu Murtugudde | Mathew RP Sapiano | Azhar Nizam | Christopher W. Brown | Antonio J. Busalacchi | Mohammad Yunus | G. Balakrish Nair | Ana I. Gil | Claudio F. Lanata - Date de Publication: 2008-11-18 - Publication: Proceedings of the National Academy of Sciences - Resumé: The causative agent of cholera, Vibrio cholerae, has been shown to be autochthonous to riverine, estuarine, and coastal waters along with its host, the copepod, a significant member of the zooplankton community. Temperature, salinity, rainfall and plankton have proven to be important factors in the ecology of V. cholerae, influencing the transmission of the disease in those regions of the world where the human population relies on untreated water as a source of drinking water. In this study, the pattern of cholera outbreaks during 1998–2006 in Kolkata, India, and Matlab, Bangladesh, and the earth observation data were analyzed with the objective of developing a prediction model for cholera. Satellite sensors were used to measure chlorophyll a concentration (CHL) and sea surface temperature (SST). In addition, rainfall data were obtained from both satellite and in situ gauge measurements. From the analyses, a statistically significant relationship between the time series for cholera in Kolkata, India, and CHL and rainfall anomalies was determined. A statistically significant one month lag was observed between CHL anomaly and number of cholera cases in Matlab, Bangladesh. From the results of the study, it is concluded that ocean and climate patterns are useful predictors of cholera epidemics, with the dynamics of endemic cholera being related to climate and/or changes in the aquatic ecosystem. When the ecology of V. cholerae is considered in predictive models, a robust early warning system for cholera in endemic regions of the world can be developed for public health planning and decision making.

Auteur(s): Didier Bompangue | Patrick Giraudoux | Pascal Handschumacher | Martine Piarroux | Bertrand Sudre | Mosiana Ekwanzala | Ilunga Kebela | Renaud Piarroux - Date de Publication: 2008-05 - Publication: Emerging infectious diseases

Auteur(s): Guillaume Constantin de Magny | Jean-François Guégan | Michel Petit | Bernard Cazelles - Date de Publication: 2007-03-19 - Publication: BMC Infectious Diseases - Resumé: Background: The relationship between cholera and climate was explored in Africa, the continent with the most reported cases, by analyzing monthly 20-year cholera time series for five coastal adjoining West African countries: Côte d'Ivoire, Ghana, Togo, Benin and Nigeria. Methods: We used wavelet analyses and derived methods because these are useful mathematical tools to provide information on the evolution of the periodic component over time and allow quantification of non-stationary associations between time series. Results: The temporal variability of cholera incidence exhibits an interannual component, and a significant synchrony in cholera epidemics is highlighted at the end of the 1980's. This observed synchrony across countries, even if transient through time, is also coherent with both the local variability of rainfall and the global climate variability quantified by the Indian Oscillation Index. Conclusion: Results of this study suggest that large and regional scale climate variability influence both the temporal dynamics and the spatial synchrony of cholera epidemics in human populations in the Gulf of Guinea, as has been described for two other tropical regions of the world, western South America and Bangladesh.

Auteur(s): Rita R. Colwell | Anwar Huq | M. Sirajul Islam | K. M. A. Aziz | Md Yunus | N. Huda Khan | A. Mahmud | R. Bradley Sack | G. B. Nair | J. Chakraborty - Date de Publication: 2003-02-04 - Publication: Proceedings of the National Academy of Sciences - Resumé: Based on results of ecological studies demonstrating that Vibrio cholerae, the etiological agent of epidemic cholera, is commensal to zooplankton, notably copepods, a simple filtration procedure was developed whereby zooplankton, most phytoplankton, and particulates >20 μm were removed from water before use. Effective deployment of this filtration procedure, from September 1999 through July 2002 in 65 villages of rural Bangladesh, of which the total population for the entire study comprised ≈133,000 individuals, yielded a 48% reduction in cholera (P < 0.005) compared with the control.

Resumé: The origin of cholera has been elusive, even though scientific evidence clearly shows it is a waterborne disease. However, standard bacteriological procedures for isolation of the cholera vibrio from environmental samples, including water, between epidemics generally were unsuccessful. Vibrio cholerae, a marine vibrio, requiring salt for growth, enters into a dormant, viable but nonculturable stage when conditions are unfavorable for growth and reproduction. The association of Vibrio cholerae with plankton, notably copepods, provides further evidence for the environmental origin of cholera, as well as an explanation for the sporadic and erratic occurrence of cholera epidemics. On a global scale, cholera epidemics can now be related to climate and climatic events, such as El Niño, as well as the global distribution of the plankton host. Remote sensing, with the use of satellite imagery, offers the potential for predicting conditions conducive to cholera outbreaks or epidemics.