Table 2.

Factors influencing the probability of an individual field vole becoming infected with A. phagocytophilum showing the best model for (a) all captures conforming to inclusion criteria described in text and (b) all such captures where the animal was also caught in the preceding month. ΔAIC=the change in the AIC if the single term is dropped. σ²=the variance attributable to a random effect. sd=standard deviation of σ²

Term	Coefficient (SE)	z-value	P-value	ΔAIC
(a) Model for all captures
Intercept	−2.72 (0.35)	−7.88	<0.001	—
Autumn	−0.33 (0.47)	−0.70	0.48	—
Male	0.24 (0.30)	0.81	0.42	—
Recapture	−0.84 (0.26)	−3.16	0.002	9.3
Males in autumn	−1.16 (0.51)	−2.28	0.023	4.2
B. microti	0.69 (0.24)	2.87	0.004	7.3
Random effect: site * session	σ2=0.58; sd=0.76
(b) Model for data of animals caught in preceding month
Intercept	−4.05 (0.43)	−9.48	<0.001	—
Chronic B. microti	0.43 (0.48)	0.88	0.38	10
New B. microti	2.17 (0.56)	3.86	<0.001
Random effect: site * session	σ2=1.03; sd=1.01