Volcanic activity controls cholera outbreaks in the East African Rift

International audienceWe hypothesized that Cholera (Vibrio cholerae) that appeared along Lake Kivu in theAfrican Rift in the seventies, might be controlled by volcano-tectonic activity, which, byincreasing surface water and groundwater salinity and temperature, may partly rule thewater characteristics of Lake Kivu and promote V. cholerae proliferation. Volcanic activity(assessed weekly by the SO2 flux of Nyiragongo volcano plume over the 2007–2012 period)is highly positively correlated with the water conductivity, salinity and temperature of theKivu lake. Over the 2007–2012 period, these three parameters were highly positively correlatedwith the temporal dynamics of cholera cases in the Katana health zone that border thelake. Meteorological variables (air temperature and rainfall), and the other water characteristics(namely pH and dissolved oxygen concentration in lake water) were unrelated to choleradynamics over the same period. Over the 2016–2018 period, we sampled weekly lake watersalinity and conductivity, and twice a month vibrio occurrence in lake water and fish. Theabundance of V. cholerae in the lake was positively correlated with lake salinity, temperature,and the number of cholera cases in the population of the Katana health zone. V. choleraeabundance in fishes was positively correlated with V. cholerae abundance in lakewater, suggesting that their consumption directly contaminate humans. The activity of thevolcano, by controlling the physico-chemical characteristics of Lake Kivu, is therefore amajor determinant of the presence of the bacillus in the lake. SO2 fluxes in the volcanoplume can be used as a tool to predict epidemic risks