Fig. 2

Correlogram of monthly and annual human WNV reports. Dotted blue lines indicate coverage probability of 95% confidence interval (CI), outside which correlations are considered significant. Autocorrelations at 1-month and 12-month lags are significant for monthly cases (95% CI: -0.18–0.18). However, autocorrelation at the annual level is not significant (95% CI: -0.51–0.51). Correlation at the monthly scale may be more meaningful than correlation observed at the annual level