Emerson Paul M, Lindsay Steve W, Alexander Neal, Bah Momodou, Dibba Sheik-Mafuji, Faal Hannah B, Lowe Kebba O, McAdam Keith P W J, Ratcliffe Amy A, Walraven Gijs E L, Bailey Robin L
Medical Research Council Laboratories, PO Box 273, Banjul, The Gambia.
Lancet. 2004 Apr 3;363(9415):1093-8. doi: 10.1016/S0140-6736(04)15891-1.
Eye-seeking flies have received much attention as possible trachoma vectors, but this remains unproved. We aimed to assess the role of eye-seeking flies as vectors of trachoma and to test provision of simple pit latrines, without additional health education, as a sustainable method of fly control.
In a community-based, cluster-randomised controlled trial, we recruited seven sets of three village clusters and randomly assigned them to either an intervention group that received regular insecticide spraying or provision of pit latrines (without additional health education) to each household, or to a control group with no intervention. Our primary outcomes were fly-eye contact and prevalence of active trachoma. Frequency of child fly-eye contact was monitored fortnightly. Whole communities were screened for clinical signs of trachoma at baseline and after 6 months. Analysis was per protocol.
Of 7080 people recruited, 6087 (86%) were screened at follow-up. Baseline community prevalence of active trachoma was 6%. The number of Musca sorbens flies caught from children's eyes was reduced by 88% (95% CI 64-100; p<0.0001) by insecticide spraying and by 30% (7-52; p=0.04) by latrine provision by comparison with controls. Analysis of age-standardised trachoma prevalence rates at the cluster level (n=14) showed that spraying was associated with a mean reduction in trachoma prevalence of 56% (19-93; p=0.01) and 30% with latrines (-81 to 22; p=0.210) by comparison with the mean rate change in the controls.
Fly control with insecticide is effective at reducing the number of flies caught from children's eyes and is associated with substantially lower trachoma prevalence compared with controls. Such a finding is consistent with flies being important vectors of trachoma. Since latrine provision without health education was associated with a significant reduction in fly-eye contact by M sorbens, studies of their effect when combined with other trachoma control measures are warranted.
嗜眼蝇作为沙眼可能的传播媒介已受到广泛关注，但这一点仍未得到证实。我们旨在评估嗜眼蝇作为沙眼传播媒介的作用，并测试提供简易坑式厕所（不进行额外的健康教育）作为一种可持续的苍蝇控制方法的效果。
在一项基于社区的整群随机对照试验中，我们招募了七组，每组三个村庄群，并将它们随机分配到干预组或对照组。干预组对每户家庭定期进行杀虫剂喷洒或提供坑式厕所（不进行额外的健康教育），对照组不进行任何干预。我们的主要结局是苍蝇与眼睛的接触情况以及活动性沙眼的患病率。每两周监测一次儿童苍蝇与眼睛接触的频率。在基线和6个月后对整个社区进行沙眼临床症状筛查。分析按照方案进行。
在招募的7080人中，6087人（86%）在随访时接受了筛查。活动性沙眼的基线社区患病率为6%。与对照组相比，通过杀虫剂喷洒，从儿童眼睛捕获的索氏家蝇数量减少了88%（95%置信区间64 - 100；p<0.0001），通过提供厕所减少了30%（7 - 52；p = 0.04）。对整群水平（n = 14）的年龄标准化沙眼患病率进行分析表明，与对照组的平均患病率变化相比，喷洒杀虫剂使沙眼患病率平均降低了56%（19 - 93；p = 0.01），提供厕所降低了30%（ - 81至22；p = 0.210）。
使用杀虫剂控制苍蝇可有效减少从儿童眼睛捕获的苍蝇数量，与对照组相比，沙眼患病率也显著降低。这一发现与苍蝇是沙眼的重要传播媒介一致。由于在不进行健康教育的情况下提供厕所与索氏家蝇与眼睛的接触显著减少有关，因此有必要研究其与其他沙眼控制措施联合使用时的效果。
