Associations between public awareness, local precipitation, and cholera in Yemen in 2017

In 2017–18, a large-scale cholera outbreak swept Yemen. We calculated the number of culture-confirmed cases from the suspected cases and diagnosis testing records. We estimate 184,248 confirmed cholera cases between April 2017 and the end of 2017, and the reproduction number of 2.2 with 95% CI of [2.1, 2.3] during the initial stage. We find a significantly (nonlinear) positive association between the reproduction number (R_t) and precipitation, explained 13% of transmissibility changes, with one unit (mm) increment in precipitation leading to an increment of 20.1% in R_t. We find a significantly (nonlinear) negative association between the R_t and cumulative Google Trends index (GTI), explained 62% of transmissibility changes, with one unit increment in cumulative GTI leading to a drop of 0.03% in R_t.