Cholera Incidence and Mortality in Sub-Saharan African Sites during Multi-country Surveillance.

BACKGROUND: Cholera burden in Africa remains unknown, often because of weak national surveillance systems. We analyzed data from the African Cholera Surveillance Network (www.africhol.org). METHODS/ PRINCIPAL FINDINGS: During June 2011-December 2013, we conducted enhanced surveillance in seven zones and four outbreak sites in Togo, the Democratic Republic of Congo (DRC), Guinea, Uganda, Mozambique and Cote d'Ivoire. All health facilities treating cholera cases were included. Cholera incidences were calculated using culture-confirmed cholera cases and culture-confirmed cholera cases corrected for lack of culture testing usually due to overwhelmed health systems and imperfect test sensitivity. Of 13,377 reported suspected cases, 34% occurred in Conakry, Guinea, 47% in Goma, DRC, and 19% in the remaining sites. From 0-40% of suspected cases were aged under five years and from 0.3-86% had rice water stools. Within surveillance zones, 0-37% of suspected cases had confirmed cholera compared to 27-38% during outbreaks. Annual confirmed incidence per 10,000 population was <0.5 in surveillance zones, except Goma where it was 4.6. Goma and Conakry had corrected incidences of 20.2 and 5.8 respectively, while the other zones a median of 0.3. During outbreaks, corrected incidence varied from 2.6 to 13.0. Case fatality ratios ranged from 0-10% (median, 1%) by country. CONCLUSIONS/SIGNIFICANCE: Across different African epidemiological contexts, substantial variation occurred in cholera incidence, age distribution, clinical presentation, culture confirmation, and testing frequency. These results can help guide preventive activities, including vaccine use.

Cholera surveillance in Uganda: an analysis of notifications for the years 2007-2011.

INTRODUCTION: Cholera outbreaks have occurred periodically in Uganda since 1971. The country has experienced intervals of sporadic cases and localized outbreaks, occasionally resulting in prolonged widespread epidemics. METHODS: Cholera surveillance data reported to the Uganda Ministry of Health from 2007 through 2011 were reviewed to determine trends in annual incidence and case fatality rate. Demographic characteristics of cholera cases were analyzed from the national line list for 2011. Cases were analyzed by district and month of report to understand the geographic distribution and identify any seasonal patterns of disease occurrence. RESULTS: From 2007 through 2011, Uganda registered a total of 7615 cholera cases with 181 deaths (case fatality rate = 2.4%). The absolute number of cases and incidence per 100 000 varied from year to year with the highest incidence occurring in 2008 following heavy rainfall and flooding in eastern Uganda. For 2011, cholera cases occurred in 1.6 times more males than females. The geographical areas affected by the outbreaks shifted each year, with the exception of a few endemic districts. No clear seasonal trends in cholera occurrence were identified for this time period. CONCLUSIONS: We observed an overall decline in cases reported during the 5 years under review. During this period, concerted efforts were made by the Ugandan government and development partners to educate communities on proper sanitation and hygiene and provide safe water and timely treatment. Mechanisms to ensure timely and complete cholera surveillance data are reported to the national level should continue to be strengthened.