Table 1. Final negative binomial model for monthly count of reported Visceral Leishmaniaisis (VL) cases in Muzaffarpur district from 2000 to 2008.

Exploratory Variable	IRR	z	P-value	95% CI
Relative humidity same month	0.98	−4.96	<0.001	0.97–0.98
Monthly relative humidity lagged by 3 months	0.98	−5.48	<0.001	0.97–0.98
Monthly rainfall lagged by 2 months	1.69	3.26	0.001	1.23–2.32
Total rainfall in the previous year	0.87	−2.49	0.013	0.78–0.97
Linear effect of year	1.14	7.99	<0.001	1.12–1.18
VL cases reported in the previous month	1.0012	3.33	0.001	1.0004–1.0019

Results presented as Incidence Rate Ratio (IRR).