The association of WNV seroprevalence with age in 2002 and 2013.

<p>No significant differences were observed in the seroprevalence between the different age groups except for the youngest age group (1–3 yr) in 2002, in which a significant lower seroprevalence was observed. *P<0.05.</p

Univariate analysis for demographic risk factors associated with WNV seroprevalence in horses in Israel in 2002 (n = 827).

<p>OR: odds ratio; CI: confidence interval; P: p value; REF: reference variable.</p><p>Age was not recorded for 7/827 horses. Breed was not recorded for 19/827 horses.</p><p>Univariate analysis for demographic risk factors associated with WNV seroprevalence in horses in Israel in 2002 (n = 827).</p

Logistic regression model for the association of WNV seroprevalence in horses in Israel with demographic (age, gender, breed, colour) and geographical/environmental (Great Rift Valley - GRV) risk factors in 2002 (n = 802).

<p>Exp(B): odds ratio (the exponentiation of the B coefficient); S.E.: standard error; CI: confidence interval; GRV: Great Rift Valley; REF: reference variable.</p><p>Logistic regression model for the association of WNV seroprevalence in horses in Israel with demographic (age, gender, breed, colour) and geographical/environmental (Great Rift Valley - GRV) risk factors in 2002 (n = 802).</p

Average spring and autumn/winter precipitation (mm) in the years 1997–2007.

<p>Arrows represent years with documented increased human WNV incidence. Between 1997–2007, the average spring precipitation (mm) was significantly lower (P<0.05) in the group of years belonging to the “increased WNV incidence” (arrows), as compared to the rest of the years. No differences in average autumn/winter precipitations were noted.</p

Spatial distribution of WNV seroprevalence in horses in Israel during 1997, 2002 and 2013.

<p>Circles inside the dashed orange marking represent farms located in the Great Rift Valley (GRV) area.</p

Univariate analyses for the association of WNV seroprevalence in horses in Israel and the geographical location of the horses along the Great Rift Valley - GRV (1997, 2002, 2013).

<p>OR: odds ratio; CI: confidence interval; P: p value; REF: reference variable; GRV: Great Rift Valley.</p><p>*Prevalence ratio.</p><p>Univariate analyses for the association of WNV seroprevalence in horses in Israel and the geographical location of the horses along the Great Rift Valley - GRV (1997, 2002, 2013).</p