Cholera in Africa: genomic and epidemiologic data identify 3–4 cross-border transmission units

Authors combined phylogeographic methods with epidemiologic data to show where cholera crosses borders more often in Africa. The clusters were tested in simulations.

A team of researchers reported in Science Advances that cholera transmission in sub-Saharan Africa is organized into 3–4 distinct "cholera transmission units". Cross-border spread has been more frequent within each unit. The authors used traditional phylogeographic techniques together with new methods that combine epidemiologic and genomic data science.org.

The units group into two major clusters. One covers Western Africa and bordering countries; the other spans the Central, Eastern and Southern regions. In simulation studies, the authors used these clusters to assess the risk of international spread of introduced cholera strains and to identify differences in the speed of spread depending on where an outbreak starts.

The methods also allow the authors to infer cholera incidence attributable to specific lineages when no sequencing data are available. According to the authors, the work has clear implications for cholera control.