Agbevo Abel, Syme Thomas, Fagbohoun Josias, Fongnikin Augustin, Ahoga Juniace, Accrombessi Manfred, Protopopoff Natacha, Cook Jackie, Churcher Thomas S, Padonou Gil G, Sovi Arthur, Ahogni Idelphonse, Govoetchan Renaud, Todjinou Damien, Akogbeto Martin, Ngufor Corine
London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.
Malar J. 2024 Dec 18;23(1):388. doi: 10.1186/s12936-024-05199-0.
Cluster-randomized controlled trials (cluster-RCTs) have demonstrated variation in the epidemiological efficacy of different next-generation insecticide-treated net (ITN) types, with some providing shorter-lived impact than others. Further studies are needed to assess changes in the insecticidal durability of these ITNs over time to complement cluster-RCT results.
A series of experimental hut trials were performed to evaluate the bioefficacy of new and field-aged next-generation ITNs (PermaNet 3.0, Royal Guard, Interceptor G2) compared to a pyrethroid-only net (Interceptor) against pyrethroid-resistant malaria vectors in Covè, southern Benin. Field-aged nets were withdrawn from households at 12, 24 and 36 months. Net pieces cut from whole ITNs were analysed for chemical content, and susceptibility bioassays were performed during each trial to assess changes in insecticide resistance in the Covè vector population.
Interceptor G2 induced superior mosquito mortality than the other ITNs across all time points. The improved mortality with Interceptor G2 compared to Interceptor was evident across all time points but was greater with new nets (odds ratio (OR) = 8.6, 95% CI [7.4, 10.1]) than field-aged nets (OR = 2.5, 95% CI [1.8, 3.5] at 12 months, OR = 2.4, 95% CI [1.6, 3.7] at 24 months and OR = 2.9, 95% CI [1.6, 5.1] at 36 months). New Royal Guard reduced mosquito fertility compared to the other ITNs, but this improvement fell after field-ageing, particularly at 24 months when it was similar to Interceptor (11% vs 3%, p = 0.08). When new, mortality was significantly higher with PermaNet 3.0 compared to Interceptor (OR = 3.6, 95% CI [3.0, 4.2]); however, this benefit was lost with field-aged nets at 12 months (OR = 1.1, 95% CI [0.8, 1.5]) and 24 months (OR = 0.6, 95% CI [0.4, 0.9]). Retention of the non-pyrethroid compound in next-generation nets was low after 36 months (27% for PermaNet 3.0, 26% for Royal Guard and 15% for Interceptor G2).
Interceptor G2 outperformed the other ITNs, confirming the superiority of pyrethroid-chlorfenapyr nets over other net types. When new, all next-generation ITNs showed superior bioefficacy compared to Interceptor; however, the size of this improvement fell after field-ageing due to poor durability of the non-pyrethroid compound. These findings emphasize the need to enhance the insecticidal durability of next-generation ITNs.
整群随机对照试验（cluster-RCTs）已证明不同类型的新一代杀虫剂处理蚊帐（ITN）在流行病学效果上存在差异，其中一些的效果持续时间比其他的短。需要进一步研究来评估这些ITN的杀虫耐久性随时间的变化，以补充整群随机对照试验的结果。
在贝宁南部的科韦，进行了一系列实验小屋试验，以评估新型和使用过一段时间的新一代ITN（PermaNet 3.0、皇家卫士、Interceptor G2）与仅含拟除虫菊酯的蚊帐（Interceptor）相比，对具有拟除虫菊酯抗性的疟疾媒介的生物有效性。使用过一段时间的蚊帐在12、24和36个月时从家庭中收回。从完整的ITN上剪下的蚊帐碎片进行化学含量分析，并在每次试验期间进行敏感性生物测定，以评估科韦媒介种群中杀虫剂抗性的变化。
在所有时间点，Interceptor G2诱导的蚊子死亡率均高于其他ITN。与Interceptor相比，Interceptor G2在所有时间点的死亡率改善都很明显，但新蚊帐（优势比（OR）=8.6，95%置信区间[7.4,10.1]）比使用过一段时间的蚊帐更显著（12个月时OR=2.5，95%置信区间[1.8,3.5]；24个月时OR=2.4，95%置信区间[1.6,3.7]；36个月时OR=2.9，95%置信区间[1.6,5.1]）。与其他ITN相比，新的皇家卫士降低了蚊子的繁殖力，但这种改善在使用一段时间后有所下降，特别是在24个月时，与Interceptor相似（11%对3%，p=0.08）。新的PermaNet 3.0与Interceptor相比，死亡率显著更高（OR=3.6，95%置信区间[3.0,4.2]）；然而，在12个月（OR=1.1，95%置信区间[0.8,1.5]）和24个月（OR=0.6，95%置信区间[0.4,0.9]）时，使用过一段时间的蚊帐失去了这种优势。36个月后，新一代蚊帐中非拟除虫菊酯化合物的保留率较低（PermaNet 3.0为27%，皇家卫士为26%，Interceptor G2为15%）。
Interceptor G2的性能优于其他ITN，证实了拟除虫菊酯-氯芬那普蚊帐优于其他类型的蚊帐。新的所有新一代ITN与Interceptor相比，生物有效性均更优；然而，由于非拟除虫菊酯化合物的耐久性差，使用一段时间后这种改善程度降低。这些发现强调了提高新一代ITN杀虫耐久性的必要性。
