National Institute of Malaria Research Field Unit, Raipur 492015, India.
Malar J. 2012 Jun 10;11:189. doi: 10.1186/1475-2875-11-189.
In the present study, Interceptor®, long-lasting polyester net, 75 denier and bursting strength of minimum 250 kPa coated with alpha-cypermethrin @ 200 mg/m² was evaluated for its efficacy in reducing the mosquito density, blood feeding inhibition and malaria incidence in a tribal dominated malaria endemic area in Chhattisgarh state, central India. Its durability, washing practices and usage pattern by the community was also assessed up to a period of three years.
The study was carried out in two phases. In the first phase (September 2006 to August 2007), 16 malaria endemic villages in district Kanker were randomized into three groups, viz. Interceptor net (LN), untreated polyester net (100 denier) and without net. Malaria cases were detected by undertaking fortnightly surveillance by home visits and treated as per the national drug policy. Mosquito collections were made by hand catch and pyrethrum space spray methods from human dwellings once every month. Slide positivity rate (SPR) and malaria incidence per 1000 population (PI) were compared between the three study arms to assess the impact of use of Interceptor nets. Simultaneously, wash resistance studies were carried out in the laboratory by doing cone bioassays on Interceptor LNs washed up to 20 times. Activities undertaken in second Phase (April 2008 to October 2009) after an interval of about 18 months post-net distribution included questionnaire based surveys at every six months, i.e. 18, 24, 30 and 36 months to observe durability, usage pattern of LNs and washing practices by the community. After 36 months of field use, 30 nets were retrieved and sampled destructively for chemical analysis.
Interceptor nets were found effective in reducing the density, parity rate and blood feeding success rate of main malaria vector Anopheles culicifacies as compared to that in untreated net and no net villages. SPR in LN villages was 3.7% as compared to 6.5% in untreated and 11% in no net villages. PI in LN villages was 16.4 in comparison to 24.8 and 44.2 in untreated polyester net and no net villages respectively. In surveys carried out after three years of initial distribution, 78.7% (737/936) nets were still in possession with the households, of which 68% were used every night. An. culicifacies mortality was >80% in cone bioassays done on LNs washed up to 20 times in laboratory. Mean alpha-cypermethrin content was 43.5 ± 31.7 mg/m² on Interceptor LNs withdrawn after three years of household use against the baseline specification of 200 mg/m². A gradual increase in the proportion of holed nets was observed with the increased period of usage.
Interceptor nets were highly effective in reducing vector densities as well as malaria incidence in the study villages. Availability of 78% nets with the households in usable condition clearly indicated durability of Interceptor LNs up to three years in the rural setting of India. The nets were found to contain an effective concentration of alpha-cypermethrin against malaria vector after three years of household use.
本研究评估了长效聚酯网Interceptor（网目 75 旦尼尔，最小断裂强度 250kPa，涂覆 200mg/m²的α-氯菊酯）在减少印度恰蒂斯加尔邦部落主导的疟疾流行地区的蚊虫密度、抑制血液摄入和疟疾发病率方面的效果。还评估了社区在三年内的耐用性、洗涤习惯和使用模式。
研究分为两个阶段进行。在第一阶段（2006 年 9 月至 2007 年 8 月），将卡克尔区的 16 个疟疾流行村庄随机分为三组，即Interceptor 网（LN）、未处理的聚酯网（100 旦尼尔）和无网。通过家访每两周进行一次监测来发现疟疾病例，并根据国家药物政策进行治疗。每月一次通过人工捕捉和拟除虫菊酯空间喷雾方法从人类居所收集蚊虫。在三个研究臂之间比较滑动阳性率（SPR）和每 1000 人口疟疾发病率（PI），以评估使用Interceptor 网的影响。同时，在实验室进行锥形生物测定，对使用过的Interceptor LNs 进行了多达 20 次的洗涤，进行了耐洗性研究。在分配网后约 18 个月的第二阶段（2008 年 4 月至 2009 年 10 月）开展了活动，包括每六个月进行一次基于问卷调查的调查，即 18、24、30 和 36 个月，以观察耐用性、LN 的使用模式和社区的洗涤习惯。在现场使用 36 个月后，回收了 30 个网并进行破坏性取样进行化学分析。
Interceptor 网在降低主要疟疾传播媒介致倦库蚊的密度、配育率和血液摄入成功率方面被证明是有效的，与未处理的网和无网村庄相比。LN 村的 SPR 为 3.7%，而未处理的和无网村的 SPR 分别为 6.5%和 11%。LN 村的 PI 为 16.4，而未处理的聚酯网和无网村的 PI 分别为 24.8 和 44.2。在初始分配三年后进行的调查中，78.7%（936 户中的 737 户）的家庭仍持有蚊帐，其中 68%的家庭每天晚上都使用。在实验室进行的锥形生物测定中，对洗涤了 20 次的 LNs 进行测试，An. culicifacies 的死亡率>80%。Interceptor LNs 在家庭使用三年后的平均 α-氯菊酯含量为 43.5±31.7mg/m²，而基线规格为 200mg/m²。随着使用时间的延长，网眼的比例逐渐增加。
Interceptor 网在降低研究村庄的蚊虫密度和疟疾发病率方面非常有效。在印度农村环境中，有 78%的家庭拥有可用的蚊帐，这清楚地表明了Interceptor LNs 的耐用性长达三年。经过三年的家庭使用，发现网中含有有效浓度的α-氯菊酯，可有效对抗疟疾媒介。
