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Table 1 Field activities by country

From: Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity

Country Angola Benin Kenya Malawi Mozambique Senegal Zambia
Years 2011–2014 2011–2014 2009–2014 2009–2013 2008–2011 2010–2013 2012–2014
Sites 4 municipalities in 2 provinces (Kwanza Sul and Uije) 6 sites Gem District Chikhwawa District 6 sites in Nampula Province (Malema, Chiulo, Ribaue, Quinga, Chinga, Angoche) 5–6 villages, depending on the number of LLINs available 4 districts in Luapula Province and 4 districts in Northern Province
Target nets distributed 2671 nets 500 per site (2 sites for retrospective, 4 sites for prospective) 4505 (attrition) 3120 (attrition) 6000 were barcoded, 2023 were found in mapping exercise 600 per village 500 each brand, distributed Feb-June 2011 (nets not distributed as part of study)
Frequency of Follow up Annual Every 6 months Every 6 months Every 6 months Annually Every 6 months Every 6 months
Mean Households interviewed at each follow up (range) 230 (153–307) 1426 (978–1821) 3745 (2962–4383) 2369 (1948–2693) 214 (198–232) 1919 (747–3151) 815 (545–999)
Average Percentage of nets examined for holes (%) 48.9 51.0 13.1a 7.5a 69.8 69.7 78.7
Assignment of LLIN brands to sites Not random Not random Randomly assigned to several villages (at least two villages per brand) Olyset Net was tested in one area only. Other LLIN brands distributed randomly Not random 5 LLIN brands tested concurrently in 17 villages Not random
Study design Repeated cross-sections of 50 households per district once per year Retrospective 2-year-post (2007–2008). Prospective with visits every 6-monthly (2011 on) Prospective, with surveys every 6 months Prospective, with surveys every 6 months Repeated cross-sections of 30 LLINs collected per site once per year Prospective, with surveys every 6 months Prospective (each Peace Corps Volunteer followed 25 LLINs for length of study with surveys every 6 months)
Quantification of hole size Measurement of long axis to the nearest centimeter; holes < 0.5 cm recorded as < 0.5 cm. 0.5–1 cm recorded as 1 cm Categories: (I—smaller than a coin); (II—between coin and hand size); (III—larger than a hand); Length at widest point; distance from bottom of the LLIN Small (< 2 cm rod), medium (> 2 cm rod, < 9 cm rod), large (> 9 cm rod) Measurement of long axis to the nearest centimeter; for 0.5–1 cm holes record as 1 cm, for < 0.5 cm record as < 0.5 cm Counted by size (< 5 cm vs > 5 cm) and placement (top, side, or bottom) Classified relative to thumb size (0.5–2 cm)
Laboratory hole counting Yes No Yes Yes Yes Yes No
  1. aIn both Kenya and Malawi 30 randomly sampled nets were selected for hole counting and chemistry every 6 months for first 2.5 years; in later surveys 50 were selected