Table 1. VL incidence and affected households before and after bed-net impregnation program, Bangladesh, 2006–2010*.

Group	Bed-net impregnation		Rate changes (p value)	% Reduction† compared with control (p value)‡
	Before, no. (%) affected	After, no. (%) affected
HH§
Intervention, n = 2,512	40 (15.92)	3 (1.19)	–14.73 (<0.0001)	–70.52% (0.0007)
Control, n = 3,143	21 (6.68)	10 (3.18)	–3.50 (0.0476)
Total, n = 5,655	61 (10.79)	13 (2.30)	–8.49 (<0.0001)
Population¶
Intervention, n = 11,426	43 (37.63)	3 (2.63)	–35.01(<0.0001)	–66.49% (0.001)
Control, n = 14,021	26 (18.54)	12 (8.56)	–9.99 (0.023)
Total, n = 25,447	69 (27.12)	15 (5.89)	–21.22 (<0.0001)

*VL, visceral leishmaniasis; HH, households.
†Effect of intervention: (B/A) – (D/C) Where A = baseline value for VL-affected HH per 1,000 HH/VL incidence per 10,000 persons in the intervention area; B = post-intervention value for VL-affected HH per 1,000 HH/VL incidence per 10,000 persons in the intervention area; C = baseline value for VL-affected HH per 1,000 HH/VL incidence per 10,000 persons in the control area; D = post-intervention value for VL-affected HH per 1,000 HHs/VL incidence per 10,000 persons in the control area. The effect is negative or positive if the VL-affected HH per 1,000 HHs/VL incidence per 10,000 persons is decreased or increased after intervention. Then the percentage reduction by intervention is calculated as (EI/[A]) × 100.
‡p values were calculated by Z statistic for pre- or post-rate differences between intervention and control areas.
§Incidence per 1,000 HH.
¶Incidence per 10,000 persons.