Department of Environmental Studies, Emory University, Atlanta, Georgia, USA.
Malar J. 2013 Feb 1;12:46. doi: 10.1186/1475-2875-12-46.
Despite the extensive ownership and use of insecticide-treated nets (ITNs) over the last decade, the effective lifespan of these nets, especially their physical integrity, under true operational conditions is not well-understood. Usefulness of nets declines primarily due to physical damage or loss of insecticidal activity.
A community based cross-sectional survey was used to determine the physical condition and to identify predictors of poor physical condition for bed nets owned by individuals from communities in Kwale County, coastal Kenya. A proportionate hole index (pHI) was used as a standard measure, and the cut-offs for an 'effective net' (offer substantial protection against mosquito bites) and 'ineffective nets' (offer little or no protection against mosquito bites) were determined (pHI ≤88 (about ≤500 cm2 of holes surface area) and pHI of >88 (≥500 cm2 of holes surface area), respectively).
The vast majority (78%) of the surveyed nets had some holes. The median pHI was 92 (range: 1-2,980). Overall, half of the nets were categorized as 'effective nets' or 'serviceable nets'. Physical deterioration of nets was associated with higher use and washing frequency. Young children and older children were found to use ineffective bed nets significantly more often than infants, while the physical integrity of nets owned by pregnant women was similar to those owned by infants. Estuarine environment inhabitants owned nets with the worst physical condition, while nets owned by the coastal slope inhabitants were in fairly good physical condition. The results suggest that bed nets are optimally utilized when they are new and physically intact. Thereafter, bed net utilization decreases gradually with increasing physical deterioration, with most net owners withdrawing physically damaged nets from routine use.This withdrawal commonly happens following 1.5 years of use, making bed net use the most important predictor of physical integrity. On average, the nets were washed twice within six months prior to the survey. Washing frequency was significantly influenced by the bed net colour and bed net age. Lack of knowledge on reasons for net retreatment and the retreatment procedure was evident, while net repair was minimal and did not seem to improve the physical condition of the nets. The "catch-up" bed net distribution strategies are sufficient for ensuring adequate ownership and utilization of 'effective nets' in the targeted groups, but bi-annual mass distribution is necessary to provide similar ownership and utilization for the other groups not targeted by "catch-up" strategies.
Monitoring and maintenance strategies that will deliver locally appropriate education messages on net washing and repair will enhance the effectiveness of malaria control programmes, and further research to assess ineffective nets need is needed.
尽管在过去十年中，人们广泛拥有和使用了经杀虫剂处理的蚊帐（ITN），但这些蚊帐的实际使用寿命，尤其是在实际操作条件下的物理完整性，仍未得到充分了解。蚊帐的有用性主要由于物理损坏或杀虫剂活性丧失而降低。
采用社区为基础的横断面调查，确定个人拥有的蚊帐的物理状况，并确定导致其物理状况不佳的预测因素。比例孔指数（pHI）被用作标准衡量指标，确定“有效蚊帐”（提供对蚊虫叮咬的实质性保护）和“无效蚊帐”（提供几乎没有或没有对蚊虫叮咬的保护）的截止值（pHI≤88（约≤500cm2 的孔表面积）和 pHI＞88（≥500cm2 的孔表面积））。
调查的蚊帐中绝大多数（78％）有一些孔。中位数 pHI 为 92（范围：1-2980）。总体而言，一半的蚊帐被归类为“有效蚊帐”或“可用蚊帐”。蚊帐的物理恶化与更高的使用和洗涤频率有关。研究发现，年龄较大的儿童和儿童比婴儿更频繁地使用无效的蚊帐，而孕妇拥有的蚊帐的物理完整性与婴儿拥有的蚊帐相似。河口环境居民拥有的蚊帐物理状况最差，而沿海坡居民拥有的蚊帐则状况良好。结果表明，当新的和完整的物理状态下，蚊帐得到最佳利用。此后，随着物理恶化程度的增加，蚊帐的利用率逐渐下降，大多数蚊帐所有者会将物理损坏的蚊帐从常规使用中撤出。这种撤出自使用 1.5 年后开始，这使得蚊帐的使用成为物理完整性的最重要预测因素。平均而言，在调查前的六个月内，蚊帐每两个月洗一次。洗涤频率受蚊帐颜色和蚊帐年龄的显著影响。显然，人们缺乏有关重新处理蚊帐的原因和处理程序的知识，而蚊帐的修复很少，并且似乎没有改善蚊帐的物理状况。“追赶”蚊帐分配策略足以确保目标群体中“有效蚊帐”的充分拥有和利用，但需要每两年进行一次大规模分配，以确保其他未被“追赶”策略覆盖的群体也能拥有和利用类似的蚊帐。
监测和维护策略将提供有关蚊帐洗涤和修复的当地适当教育信息，这将增强疟疾控制规划的有效性，还需要进一步研究来评估无效蚊帐的需求。
