Eric Mintz , 2 Gopinath

The current supplement presents an overview of cholera disease burden and critical issues for the diagnosis, detection, prevention, and control of cholera in Africa. In 2013, the seventh cholera pandemic reached its 43rd year in Africa, with no evidence that it will end soon. More than 20 African countries have reported cholera to the World Health Organization (WHO) every year between 2007 and 2012, including large recent epidemics in the Democratic Republic of Congo (DRC), Sierra Leone, Uganda, Ghana, Niger, and Guinea [1]. In the current supplement, articles from individual countries highlight the human toll of cholera, including more than 200 000 cases and 7000 deaths in DRC from 2000 through 2008 [2]; 68 000 cases and 2600 deaths in Kenya from 1998 through 2010 [3]; 28 000 cases and 1300 deaths in Cameroon from 2010 through 2011 [4]; 25 000 cases and 220 deaths in Mozambique from 2009 through 2011 [5]; and more than 12 000 cases and 500 deaths in Togo from 1996 through 2010 [6]. Two patterns emerge from these reports. The first is endemic, as in DRC, where cholera has occurred continuously in specific regions with an increase in the number of outbreaks during the rainy season. The second pattern is epidemic or outbreak driven, as in Mozambique, where many districts have been affected over relatively short periods, separated by prolonged quiescent periods. Although factors such as climate might increase outbreak risk, in these settings it remains difficult to predict the specific districts or communities that will be affected during any given year. Difficulties in interpreting country-level data exist. Most African countries currently rely on reporting of aggregate data from the district level, whose completeness remains unknown. This could lead to serious underestimation of cholera burden that is likely to vary by geographic area, age group, or other risk factors. A reliance on aggregate data that are limited to case counts and deaths prevents evaluation by basic demographic features such as age, gender, and town of residence, making identification and targeting of high-risk groups difficult. Additionally, in most circumstances, countries have collected data on suspected cholera cases based on clinical symptoms rather than laboratory confirmation. Although this has the distinct advantage of conserving laboratory resources and, practically, might be justified during large outbreaks, to the extent that other acute diarrheal illnesses occur simultaneously with cholera, it might lead to overestimation of cholera burden. Complicating this situation are changes in cholera case definitions, such as those that occurred in Cameroon [4]. In 2 articles, Rebaudet and colleagues distinguish between coastal [7] and inland [8] cholera, arguing that unlike in Bangladesh, cholera in Africa is not driven primarily by the impact of climate on coastal aquatic reservoirs. Instead, the majority of African epidemics have occurred inland, in areas such as the Great Lakes Region, Lake Chad Basin, and the Sahelian belt. Nevertheless, water does play a critical role in cholera transmission and amplification in Africa. In coastal areas, most outbreaks occur near estuaries, lagoons, mangrove forests, and on islands, while inland cholera epidemics most often have their “roots” and “branches” along rivers and lakes. In all settings, climatic disruptions in water supply—either droughts or floods—are likely to increase cholera incidence by altering access to and safety of drinking water supplies and the ability to maintain proper sanitation. So what can be done? Fortunately, large strides have been made. In all settings reported in this supplement, cholera case fatality ratios have decreased dramatically, at least at the country level, even if not within all regions or Correspondence: Bradford D. Gessner, AMP, Bureau de liaison. Immeuble JB Say 13 Chemin du Levant, 01210 Ferney-Voltaire, France ([email protected]). The Journal of Infectious Diseases 2013;208(S1):S1–3 © The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: [email protected]. DOI: 10.1093/infdis/jit403