Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance

Table 3 Bio-assay results for 200 LLINs and deltamethrin concentration of 40 selected LLINs three years after distribution in five provinces in Afghanistan, 2015

	All provinces	Balkh province	Herat province	Khost province	Kunduz province	Nangarhar province	P value
Bio-assay results (on 200 LLINs)
Median mosquito knock-down rate*, % (IQR)	92 (84–97)	90 (76–97)	90 (81–96)	94 (90–98)	91 (85–97)	91 (81–97)	< 0.0001
Median mosquito mortality, % (IQR)	58 (36–84)	50 (18–79)	55 (43–82)	69 (41–86)	71 (48–86)	55 (27–80)	< 0.0001
Percentage of LLINs meeting the ≥ 95% mosquito knock-down criterion*	37	35	31	48	35	35	0.654
Percentage of LLINs meeting the ≥ 80% mosquito mortality criterion*	28	25	21	35	38	23	0.307
Percentage of LLINs meeting the WHOPES criteria (≥ 95% mosquito knock-down or ≥ 80% mosquito mortality)*	44	40	35	55	48	43	0.437
Deltamethrin measurement results (on 34 LLINs)
Median Deltamethrin concentration*^,† (g/kg netting material) (IQR)	0.12 (0.03–0.27)	0.09 (0.03–0.31)	0.11 (0.08–0.23)	0.23 (0.02–0.87)	0.14 (0.02–0.34)	0.17 (0.03–0.26)	0.99

IQR = interquartile range; kdr = knock-down rate; LLIN = Long-lasting Insecticidal Nets; WHOPES = World Health Organization Pesticide Evaluation Scheme
*Calculation based on the average of the four position-specific measurements per LLIN
^†Analysis done on a random sub-selection of 34 LLINs (5–8 per province)

ISSN: 1475-2875