Vector Control Unit, Environmental Health Department, Ministry of Health, Ramallah, Palestine.
Mediterranean and Black Sea Field Epidemiology Training Programme-MediPIET, Madrid, Spain.
PLoS Negl Trop Dis. 2022 Sep 13;16(9):e0010628. doi: 10.1371/journal.pntd.0010628. eCollection 2022 Sep.
Zoonotic cutaneous leishmaniasis (ZCL) is endemic in Palestine and transmitted by Phlebotomus sand flies. They inhabit dens of hyraxes, the reservoir animal. Control measures were implemented since 1996 but cases still occur. We estimated the effect of insecticide thermal fogging inside hyrax dens on sand fly density and leishmania infection.
METHODOLOGY/PRINCIPAL FINDINGS: During July-September 2019, we conducted a 12-week controlled interrupted time series study in two control and one intervention sites containing three hyrax dens each. We implemented Permethrin thermal fogging in the intervention site at week 6. We measured weekly and 36hrs post-intervention sand fly abundance inside dens using CDC light traps. We performed Next-Generation Sequencing to identify sand fly Leishmania spp. infection. We calculated the abundance reduction (AR) using Mulla's formula and negative binomial regression. Among 11427 collected sand flies, 7339 (64%) were females and 1786 (16%) were Phlebotomus spp. comprising ten species; P. sergenti was the dominant (n = 773, 43%). We report P. arabicus (n = 6) for the first time in Palestine. After fogging, Phlebotomus spp. AR was 93% at 36hrs, 18% and 38% at two and five weeks respectively and 41% during the complete post-intervention period. In the regression models, Phlebotomus spp. density in the intervention site decreased by 74% (IRR: 0.26, 95%CI: 0.11-0.57) at two weeks, 34% (IRR: 0.66, 95%CI: 0.48-0.90) at five weeks and 74% (IRR: 0.26, 95%CI: 0.12-0.59) during the complete period. The density of Leishmania infected sand flies decreased by 65% (IRR: 0.35, 95%CI: 0.26-0.48) at five weeks and 82% (IRR: 0.18, 95%CI: 0.07-0.42) for the complete period (zero infections until week two). Leishmania infection prevalence in the intervention site was 14% pre-intervention and 3.9% post-intervention.
CONCLUSIONS/SIGNIFICANCE: Fogging hyrax dens reduced sand fly abundance and leishmania infection during the 5-week post-intervention period and especially the first two weeks suggesting it could be an effective source-reduction measure for ZCL vectors. Future randomized controlled trials are needed to confirm the effectiveness of fogging hyrax dens on decreasing ZCL incidence.
巴勒斯坦流行动物源性皮肤利什曼病（ZCL），由沙蝇传播。沙蝇栖息在蹄兔的洞穴中，蹄兔是其储存宿主。自 1996 年以来实施了控制措施，但仍有病例发生。我们评估了在蹄兔洞穴内用杀虫剂热雾处理对沙蝇密度和利什曼原虫感染的影响。
方法/主要发现：在 2019 年 7 月至 9 月期间，我们在两个对照和一个干预点进行了为期 12 周的对照中断时间序列研究，每个点包含三个蹄兔洞穴。在第 6 周，我们在干预点实施了氯菊酯热雾处理。我们使用 CDC 诱捕器每周和干预后 36 小时测量洞穴内的沙蝇丰度。我们进行了下一代测序以鉴定沙蝇中的利什曼原虫感染。我们使用 Mulla 公式和负二项回归计算丰度减少（AR）。在收集的 11427 只沙蝇中，7339 只为雌性（64%），1786 只为 Phlebotomus spp.（16%），包括十种；其中 P. sergenti 为优势种（n = 773，43%）。我们首次在巴勒斯坦报告了 P. arabicus（n = 6）。热雾处理后，36 小时时 Phlebotomus spp. 的 AR 为 93%，两周时为 18%，五周时为 38%，整个干预后期间为 41%。在回归模型中，干预点的 Phlebotomus spp. 密度在两周时下降了 74%（IRR：0.26，95%CI：0.11-0.57），五周时下降了 34%（IRR：0.66，95%CI：0.48-0.90），整个干预期间下降了 74%（IRR：0.26，95%CI：0.12-0.59）。感染利什曼原虫的沙蝇密度在五周时下降了 65%（IRR：0.35，95%CI：0.26-0.48），整个干预期间下降了 82%（IRR：0.18，95%CI：0.07-0.42）（直至干预后两周零感染）。干预前，干预点的利什曼原虫感染率为 14%，干预后为 3.9%。
结论/意义：在干预后的 5 周内，特别是在前两周，对蹄兔洞穴进行热雾处理减少了沙蝇的数量和利什曼原虫的感染，表明这可能是一种有效的 ZCL 媒介来源减少措施。需要进行随机对照试验来证实对蹄兔洞穴进行热雾处理对降低 ZCL 发病率的有效性。
