Cholera in Africa: A Closer Look and a Time for Action

Timely, accurate, and representative data on disease occurrence are the foundation for effective, targeted prevention and control. In recent years, the achievements of disease-specific programs in Africa, including the President's Emergency Plan for AIDS Relief, the President's Malaria Initiative, and campaigns to eradicate Guinea worm and polio, have demonstrated the power of enhanced surveillance closely coupled with prevention and control measures. Broadly-based programs for strengthening public health capacity, such as the Integrated Diseases Surveillance and Response program [1], the Field Epidemiology and Laboratory Training Program [2], the African Field Epidemiology Network [3], and the EPIVAC Field Vaccinology Training Program [4], combined with new international health regulations adopted in 2005 and fully implemented in 2012 [5], have provided new resources and lent new impetus to improved surveillance, investigation, and reporting for many diseases, including cholera. In the 43 years since the seventh cholera pandemic reached Africa, in 1970, cholera has become endemic in many African countries and remains a recurring cause of large, deadly, multinational epidemics in West, Central, and East Africa. National surveillance data reported to the World Health Organization (WHO) [6–11] and outbreak data reported to ProMED [12] show the extent to which cholera has become entrenched in Africa. Each year from 2007 through 2011, at least 20 African countries reported >100 000 cases of cholera to the WHO. During this period, annual case-fatality ratios (CFRs) for cholera in the African region ranged from 2.22% to 2.95%, and they exceeded 5% in ≥1 country each year [7–11]. With effective treatment, the CFR for cholera should be <1%. In 2012, at the time of writing, 25 African nations have reported 94 553 cholera cases, including >85 293 cases from large epidemics in the Democratic Republic of Congo, Sierra Leone, Ghana, Guinea, Uganda, and Niger [13]. During the same period, 1834 cholera deaths were reported, for a regional CFR of 1.9%. Despite this grim picture, there are opportunities and reasons for optimism. The Guinea Worm Eradication program, launched in 1986, is a model for success in the most remote and challenging parts of the continent. Active community-based surveillance for this waterborne infectious disease, coupled with a vigorous intervention program based on household water treatment and improved water supply, has eliminated cases and transmission of dracunculiasis from 13 of 17 African countries and greatly reduced the number of cases in the remaining 4 countries [14]. Unlike Guinea worm infection, which can be diagnosed reliably with the naked eye, cholera requires occasional laboratory confirmation; however, a simple, practical, and inexpensive rapid diagnostic test for cholera is now commercially available. Use of this test can help trigger rapid response efforts by indicating whether an outbreak of acute watery diarrhea is likely to be cholera [15]. The recent WHO prequalification of a new 2-dose oral cholera vaccine that is less expensive and less cumbersome to deliver than its predecessor [11], the recent use of this vaccine in pilot projects in Guinea and Haiti [16], and the anticipated creation of a cholera vaccine stockpile at the WHO [17] have stimulated interest in more timely, accurate, and comprehensive surveillance from affected countries. Finally, we have encouraging news from Haiti, the site in 2010 and 2011 of one of the most explosive cholera epidemics in modern history. In much the same way as occurred when cholera struck the Americas in the early 1990s, events in Haiti galvanized public and political attention to the problem of epidemic cholera, reenergized the public health sector, and yielded new guidelines and training materials in French and English that can be of immediate benefit in Africa [18, 19]. From 1 January 2011 through 13 May 2013, Haiti has had a cumulative CFR of <1% [20]. In 2012, reported cholera cases (101 411), hospitalizations (61 823), and deaths (905) decreased by 71%, 67%, and 69% respectively, compared with 2011 [20]. While much more needs to be done to further reduce the risk of endemic cholera in Haiti over the long term, the decline in cases and in the CFR is attributable in part to significant investments in primary prevention through community education and training, dissemination of products for water treatment and hygiene, construction of basic sanitation facilities, and provision of cholera treatment supplies and training in communities and health facilities [21, 22]. Leveraging this new interest and these new prevention tools to address the cholera crisis in Africa more effectively will require several essential elements. The first is a clearer picture of the epidemiology of cholera on subregional and subnational levels. While aggregated data at the regional and national levels are conveniently packaged and easily understood, they lack the detail and timeliness needed to inform and implement efficient, targeted prevention and control measures that have been critical to the success of disease-specific programs, such as those for smallpox, polio, and dracunculiasis. Thanks to support from the Africhol project, launched in 2009 by the Agence de Médecine Préventive with funding from the Bill and Melinda Gates Foundation, cholera surveillance has been enhanced and intensified in 9 of the most heavily affected countries in Africa [23]. This supplement, supported by the Africhol project, includes several articles that greatly enhance our understanding of cholera epidemiology and prevention at the national, subnational [24–28], and subregional [29] levels. Observations from these articles can help inform more-coordinated, focused, and successful campaigns to reduce morbidity and mortality from cholera in Africa. The successful fight against cholera also requires dedicated human and financial resources. Per capita investments in cholera prevention and control in Haiti have far outstripped those typically allotted to epidemic cholera in African countries, but here too there are encouraging signs, with increased attention to cholera prevention and control in Africa from several nongovernmental organizations, including Oxfam, Médecins sans Frontières (MSF), Americares, and the International Centre for Diarrheal Diseases Research, Bangladesh (ICDDR,B). To address the extensive cholera epidemic in Sierra Leone, the government of the United Kingdom recently activated its Rapid Response Facility, a network of aid organizations and private sector partners, coordinated by the Department for International Development, while MSF, the Centers for Disease Control and Prevention, the ICDDR,B and other organizations provided on-site support to the Ministry of Health for clinical, epidemiologic, and laboratory aspects of the response. The WHO is actively seeking funding to support the initiation of a cholera vaccine stockpile, and the Bill and Melinda Gates Foundation has generously supported cholera research in Asia and, more recently, in Africa. While these efforts are welcome beginnings, much more needs to be done to address the root conditions that enable transmission of epidemic cholera and a Pandora's box of other infectious diseases—fecally contaminated drinking water and inadequate disposal of human fecal waste. In 2010, sub-Saharan Africa had the lowest population coverage with improved water sources (61%) of any region except Oceania and the lowest population coverage rates with improved sanitation facilities (30%) of any region [30]. According to a recent report by Water Aid, 40% of the global population without access to improved drinking water sources and 24% of the global population without access to improved sanitation lives in sub-Saharan Africa [30, 31]. While the globe as a whole achieved the Millennium Development Goal (MDG) for drinking water 5 years ahead of schedule, in 2010, sub-Saharan Africa is still not on track to meet that goal or the MDG for improved sanitation by the 2015 target date. The proportion of overseas development aid for water and sanitation directed to sub-Saharan Africa increased only modestly, from 22.8% in 2000–2002 to 26.5% in 2008–2010; even then, it averaged only $2.39 per person per year, barely half of the $15 billion estimated as needed each year to meet the region's MDG financing gap [31]. Mobilizing funds for major investments in water, sanitation, and hygiene in the parts of Africa that have the largest burden of endemic and epidemic cholera, through a mechanism like the “Call to Action” that was launched by the governments of Haiti and the Dominican Republic in January 2011, would yield enormous benefits if successful [32]. More precise, timely, and cross-cutting surveillance can enhance cholera prevention and control in several ways. The occurrence of cholera in specific areas is an indicator that can be used to more efficiently target rapid investments in household water treatment and sustained improvements in water supply, emulating the Guinea Worm Eradication program. Collecting timely data on case counts and case-fatality rates and linking these to rapid inventory control data from health facilities and cholera treatment centers could help prevent “death by stock out.” Stock outs occur when cholera treatment centers run out of critical treatment supplies and are a disturbingly persistent and widespread risk factor for cholera mortality [27, 33]. Informed and effective decisions on whether to use cholera vaccine to control an ongoing outbreak—so-called reactive use—requires quickly detecting and confirming the outbreak, having reliable data on the availability of resources needed for a vaccine campaign (eg, staff, vehicles, and cold storage), and using surveillance data to predict the likelihood that the outbreak will not end before resources can be mobilized, vaccine delivered, and immunity increased in the target population [25]. Developing and implementing national cholera plans has been proposed as a way to strengthen mechanisms for data collection and establish mechanisms for decision making in advance of the next cholera outbreak. The resources necessary to support more-detailed cholera surveillance and to use surveillance data to implement targeted interventions that will reduce cholera morbidity and mortality are available within the budgets of development banks and of governmental and nongovernmental agencies in Africa and elsewhere. The public health and economic benefits of investing these resources in this effort will go far beyond the costs exacted by cholera, as great as those costs are. Morbidity and mortality from other diseases spread by the same routes as cholera, including typhoid fever, dysentery, hepatitis A and E, and a broad spectrum of other parasitic, viral, and bacterial infections, will also be alleviated by improvements in water, sanitation, and hygiene. The persistence of cholera is closely correlated with elevated infant mortality [34] and is an indicator for where the risk of waterborne diseases and the need for intervention are greatest. Spurred in large part by pandemic cholera, the impact of water and sanitation improvements on infant mortality and increased life span in Europe and the United States and, more recently, in Latin America have been well documented [35, 36]. Is it not time to replicate that experience in the cradle of humankind? Financial support. This work was supported by Africhol, a project funded by the Bill and Melinda Gates Foundation. Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.