Turning points, reproduction number, and impact of climatological events for multi‐wave dengue outbreaks

Abstract

Three turning points occurred around early August, late August/early September, and late October/early November. The 'initial' reproduction number for the first wave was R(i) = 4.67 (95% CI: 0*-10.92), where 0* = max{0, lower bound}, and R(i) = 3.93 (95% CI: 1.74-6.13) for the second wave. The highest correlation was between dengue incidence and two climatological variables: maximum temperature at a lag of 5 weeks (r = 0.66 and 0.71) and total precipitation at a lag of seven weeks (r = 0.53). Conclusions The first two turning points were partially attributable to two typhoons around early to mid-August that brought a sharp drop in temperature and substantial rainfall. The drop in temperature first drove the dengue incidence down, then the rainfall drove it up at the beginning of fall. In recent years, Taiwan has witnessed increasingly frequent large summer dengue outbreaks that persisted into early winter, perhaps due to warmer autumns. This highlights the possible impact of global warming on the spread of infectious diseases.