Laboratory of Vector and Parasite Ecology (UCAD), Dakar, Senegal.
Laboratory of Parasitology (UCAD), Dakar, Senegal.
BMC Public Health. 2022 Apr 11;22(1):719. doi: 10.1186/s12889-022-13051-w.
Long lasting insecticidal nets (LLIN) are one of the core components of global malaria prevention and control. The lifespan of LLIN varies widely depending on the population or environment, and randomized studies are required to compare LLIN inaccording to arbitrary thresholds households under different field conditions. This study investigated survival of different LLIN brands in Senegal.
Ten thousand six hundred eight LLINs were distributed in five regions, each stratified by rural and urban setting. As part of the longitudinal follow-up, 2222 nets were randomly sampled and monitored from 6 to 36 months. Using random effects for households, Bayesian models were used to estimate independent survival by net type (Interceptor®, Life Net®, MAGNet™, Netprotect®, Olyset® Net, PermaNet® 2.0 R, PermaNet® 2.0 C, Yorkool® LN) and by area (rural/urban). In addition to survival, median survival time and attrition of each LLIN brand was determined. Attrition was defined as nets that were missing because they were reported given away, destroyed and thrown away, or repurposed.
Three net types had a proportion of survival above 80% after 24 months: Interceptor®87.8% (95% CI 80-93.4); conical PermaNet® 2.0 86.9% (95% CI 79.3-92.4) and Life Net® 85.6% (95% CI 75-93). At 36 months, conical PermaNet® 2.0 maintained a good survival rate, 79.5% (95% CI 65.9-88.8). The attrition due to redistributed nets showed that the two conical net types (PermaNet® 2.0 and Interceptor®) were more often retained by households and their median retention time was well above 3 years (median survival time = 3.5 years for PermaNet® 2.0 and median survival time = 4 years for Interceptor®). Despite this good retention, Interceptor® had weak physical integrity and its median survival due to wear and tear was below 3 years (median survival time = 2.4 years). The odds ratio of survival was 2.5 times higher in rural settings than in urban settings (OR 2.5; 95% CI 1.7-3.7).
Differences in survival among LLIN may be driven by brand, shape or environmental setting. In this study in Senegal, conical PermaNet® 2.0 were retained in households while rectangular PermaNet® 2.0 had lower retention, suggesting that net shape may play a role in retention and should be further investigated. Distribution of preferred LLIN shape, accompanied by good communication on care and repair, could lead to increased effective lifespan, and allow for longer intervals between universal coverage campaigns.
长效杀虫蚊帐（LLIN）是全球疟疾预防和控制的核心组成部分之一。LLIN 的使用寿命因人群或环境而异，需要进行随机研究来比较不同条件下家庭中任意阈值的 LLIN。本研究调查了塞内加尔不同 LLIN 品牌的生存情况。
在五个地区发放了 10080 顶蚊帐，每个地区按农村和城市环境分层。作为纵向随访的一部分，从第 6 到 36 个月，随机抽取并监测了 2222 顶蚊帐。使用家庭的随机效应，贝叶斯模型用于根据蚊帐类型（Interceptor®、Life Net®、MAGNet™、Netprotect®、Olyset® Net、PermaNet® 2.0 R、PermaNet® 2.0 C、Yorkool® LN）和地区（农村/城市）独立估计生存情况。除了生存情况外，还确定了每种 LLIN 品牌的中位生存时间和损耗。损耗定义为因报告赠送、损坏和扔掉或重新使用而丢失的蚊帐。
在 24 个月后，有三种蚊帐类型的存活率超过 80%：Interceptor®87.8%（95%CI80-93.4）；圆锥形 PermaNet® 2.0 86.9%（95%CI79.3-92.4）和 Life Net® 85.6%（95%CI75-93）。在 36 个月时，圆锥形 PermaNet® 2.0 保持了良好的存活率，为 79.5%（95%CI65.9-88.8）。由于重新分配的蚊帐造成的损耗表明，两种圆锥形蚊帐（PermaNet® 2.0 和 Interceptor®）更常被家庭保留，其中位保留时间远超过 3 年（PermaNet® 2.0 的中位保留时间为 3.5 年，Interceptor®的中位保留时间为 4 年）。尽管保留情况良好，但 Interceptor®的物理完整性较弱，由于磨损导致的中位生存时间低于 3 年（中位生存时间=2.4 年）。农村地区的生存几率是城市地区的 2.5 倍（OR 2.5；95%CI1.7-3.7）。
LLIN 之间的生存差异可能是由品牌、形状或环境条件驱动的。在塞内加尔的这项研究中，圆锥形 PermaNet® 2.0 被家庭保留，而矩形 PermaNet® 2.0 的保留率较低，这表明蚊帐形状可能在保留方面发挥作用，应进一步研究。分发首选的 LLIN 形状，并辅以良好的护理和修复沟通，可能会延长有效寿命，并允许延长普遍覆盖运动之间的间隔。
