Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change

Table 2 Validation of the nymphal tick immigration index.

Variable	Factor	Coefficient (SE)	Wald z
Index of tick immigration		0.043 (0.004)	10.86***
Province	Newfoundland & Labrador	Reference factor
	Saskatchewan	-2.524 (0.254)	-4.12***
	Manitoba	1.692 (0.289)	5.85***
	Ontario	-1.27 (0.299)	-4.24***
	Quebec	-0.405 (0.304)	1.33
	New Brunswick	0.482 (0.303)	1.59
	Prince Edward Island	3.131 (0.315)	9.93***
	Nova Scotia	0.583 (0.349)	1.67
Constant		-9.831 (0.254)	-38.65

*** = P < 0.001
The association of the nymphal tick immigration index with the number of I. scapularis submitted in each Canadian census sub-division in passive surveillance in Canada from 1990 to 2003 was investigated using a multivariable negative binomial regression model. In this model nymphal tick immigration index and Province were explanatory variables, and the natural logarithm of human population was included as an offset.

ISSN: 1476-072X