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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 surveillancesystems.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 zonesand four outbreak sites in Togo, the Democratic Republic of Congo (DRC), Guinea,Uganda, Mozambique and Cote d’Ivoire. All health facilities treating cholera cases wereincluded. Cholera incidences were calculated using culture-confirmed cholera cases andculture-confirmed cholera cases corrected for lack of culture testing usually due to overwhelmedhealth systems and imperfect test sensitivity. Of 13,377 reported suspectedcases, 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% hadsites. From 0–40% of suspected cases were aged under five years and from 0.3–86% hadrice water stools. Within surveillance zones, 0–37% of suspected cases had confirmed choleracompared to 27–38% during outbreaks. Annual confirmed incidence per 10,000 populationwas <0.5 in surveillance zones, except Goma where it was 4.6. Goma and Conakry hadcorrected 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 rangedfrom 0–10% (median, 1%) by country.

Conclusions/Significance

Across different African epidemiological contexts, substantial variation occurred in choleraincidence, age distribution, clinical presentation, culture confirmation, and testing frequency.These results can help guide preventive activities, including vaccine use.