Tungu Patrick, Messenger Louisa A, Kirby Matthew J, Sudi Wema, Kisinza William, Rowland Mark
National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania.
Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.
Arch Public Health. 2016 Dec 30;74:56. doi: 10.1186/s13690-016-0168-2. eCollection 2016.
Universal coverage of long-lasting insecticidal nets (LNs) made from polyester or polyethylene fibres has been adopted as the standard of care to control malaria among at-risk populations. To obtain a WHO recommendation, LNs must undergo prospective monitoring of insecticidal efficacy against mosquito vectors over 3 years of household use. The retention of bioefficacy and physical durability of a LN is influenced by net usage practices, textile polymer material and insecticide treatment technology. Fabric durability is the critical factor which determines the interval required between LN replacement campaigns. To investigate factors known to affect LN durability and bioefficacy, we describe a three-arm WHO Pesticide Evaluation Scheme (WHOPES) Phase III evaluation of a LN made uniquely from polypropylene (LifeNet®, Bayer CropScience) compared to standard LNs made from polyester and polyethylene, all treated with deltamethrin, over 3 years of use.
This is a prospective three-arm household randomized, equivalence trial of LNs in Tanzania, with nets as the unit of observation. Equal numbers of houses will be randomized to receive deltamethrin-treated polypropylene, polyester or polyethylene LNs; all sleeping spaces in a given household will be provided with one type of net. Bioefficacy (insecticidal activity against mosquitoes), insecticide content of net fibres, and fabric integrity (number, location and size of holes) will be measured every 6 months, using WHO cone or tunnel bioassays, chemical analysis and calculation of hole index, respectively. A cohort of LNs will be surveyed annually to assess survivorship (median LN survival time) and cumulative loss of fabric integrity. Field durability outcomes will be compared with laboratory strength tests.
This is the first trial to compare the relative durability of three LNs each made from a different textile polymer, treated with the same insecticide, in the same community side-by-side over 3 years of use. Trial findings will 1) guide global health organizations on procurement policy and the type of textile polymer which maximizes the interval between LN replacement campaigns, and 2) stimulate manufacturers to improve product performance and development of longer lasting polymers. A full WHO recommendation may be granted to LifeNet® upon successful Phase III completion.
采用由聚酯或聚乙烯纤维制成的长效驱虫蚊帐（LLIN）进行普遍覆盖，已被用作控制高危人群疟疾的标准护理措施。为获得世界卫生组织（WHO）的推荐，LLIN必须在家庭使用3年期间对蚊虫媒介进行杀虫效果的前瞻性监测。LLIN的生物活性和物理耐用性的保持受到蚊帐使用习惯、纺织聚合物材料和杀虫剂处理技术的影响。织物耐用性是决定LLIN更换活动所需间隔时间的关键因素。为了研究已知影响LLIN耐用性和生物活性的因素，我们描述了一项由世界卫生组织农药评价方案（WHOPES）第三阶段进行的三臂试验，该试验对一种由聚丙烯独特制成的LLIN（LifeNet®，拜耳作物科学公司）与由聚酯和聚乙烯制成的标准LLIN进行了比较，所有蚊帐均用溴氰菊酯处理，使用3年。
这是一项在坦桑尼亚进行的前瞻性三臂家庭随机等效性试验，以蚊帐作为观察单位。将相同数量的房屋随机分配，分别接受经溴氰菊酯处理的聚丙烯、聚酯或聚乙烯LLIN；给定家庭中的所有睡眠空间将配备同一种蚊帐。每6个月分别使用WHO锥形或隧道生物测定法、化学分析和孔洞指数计算来测量生物活性（对蚊子的杀虫活性）、蚊帐纤维中的杀虫剂含量以及织物完整性（孔洞的数量、位置和大小）。每年对一组LLIN进行调查，以评估其存活率（LLIN中位存活时间）和织物完整性的累积损失。将现场耐用性结果与实验室强度测试进行比较。
这是第一项在同一社区中对三种分别由不同纺织聚合物制成、使用相同杀虫剂处理的LLIN在3年使用期内的相对耐用性进行并排比较的试验。试验结果将：1）为全球卫生组织提供采购政策指导，并确定哪种纺织聚合物能最大限度延长LLIN更换活动的间隔时间；2）激励制造商提高产品性能并开发更耐用的聚合物。若第三阶段试验成功完成，LifeNet®可能会获得WHO的全面推荐。
